What is obesity and what is its impact? 2–3

How is weight controlled? Is obesity ‘in our genes’? 4–5

How does lifestyle and environment impact on our weight? 6

Real voices: obese people and an obesity doctor have their say 7, 12–13

How can we treat or prevent obesity? 10–11

Whose responsibility is it to tackle obesity? 14–15

The big picture 16

This is the era of the expanding waistline. Over the past few decades we have been steadily pilingon the pounds. One in five adult men and one infour adult women are obese. A staggering two-thirds of all men and half of all women are eitheroverweight or obese – that’s 24 million people.Globally, more than 300 million adults are obese.

BigPictureNewspapers warn of an ‘obesity timebomb’:obesity may be about to overtake smokingas the major cause of preventable disease; our children are growing up to be couch potatoes,putting down Playstations only long enough topick up the TV remote control, or the telephoneto order another pizza.

But why is obesity such a problem? Is it just a personal matter? Are we simply prejudicedagainst heavier people?

And if there is a problem, who should be doingsomething about it? Is it just down to people to show more self-control? Should foodmanufacturers be more responsible about whatthey put in their products or in how they marketthem? What about schools and parents? Or should governments intervene, slapping on ‘fat taxes’ or banning fast food advertisements?

And what have science and medicine to say? Are we likely to see wonderdrugs that keep us slim no matter what we eat? How well dowe understand the human physiology that controlsour weight? Or the psychological factors thatinfluence what (and why) we eat?

This interplay between science, medicine andsociety, and people, institutions and politics,forms the focus of this Big Picture.

OBESITYon

ISSUE 1 JANUARY 2005

The Big Picture series is the successor to LabNotes.

Up-to-date science. Real-life issues. For teachersand students. Authoritative, balanced andaccessible, the Big Picture series is the essentialguide to biomedical science and its social impact.

Rex

Fea

ture

s

2 | BIG PICTURE 1

Obesity is a sign of excess fat storage by the body. This can increasethe risk of many serious health problems. Obesity is usually classified as a disease, but we seem to have little sympathy for overweight people.

Education editor: Hannah Russell

Education adviser: Peter Finegold

Editor: Ian Jones

Writers: Jackie Adam, Penny Bailey, Lisa Melton, Julie Reza

Illustrator: Glen McBeth

Editorial advisory board: Nan Davies, Nick Finer, Susan Jebb, Wing-May Kong, Dean Madden, Michael Reiss, Neville Rigby,Dell StanfordAll images, unless otherwise indicated, are from the Wellcome Trust’s Medical Photographic Library.

The Wellcome Trust is an independent biomedicalresearch funding charity (registered charity no. 210183).The Trust’s mission is to foster and promote researchwith the aim of improving human and animal health.

Reflecting the profound impact today’s research will have on society, the Wellcome Trust also seeks to raiseawareness of the medical, ethical and social implicationsof research and promote dialogue between scientists,the public and policy makers.

© The Trustee of the Wellcome Trust, London, 2004.

All rights reserved. Except as set out below, no part of this publication may be reproduced, stored in aretrieval system, or transmitted, in any form or by anymeans, electronic, mechanical, photocopying,recording or otherwise, without the prior permission of the Wellcome Trust.

The Wellcome Trust consents to photocopies of all or part of this publication being made by educationalinstitutions for non-profit, educational classroom useprovided that the above copyright notice and anycredits attaching to images or text featured in thephotocopy appear clearly in such a photocopy.

MC-3267.p/30K/01–2005/SW

DIABETESVery strong link withobesity. Relative riskrises rapidly with weight, particularly in women

HIGH BLOODPRESSURE ANDCORONARY HEART DISEASERisk increased 3–4-fold in obesepeople

CANCERIncreased risk forcancer of the colon,breast (post-menopause), womb,kidney and oesophagus

STROKEObesity doubles therisk of stroke

The increasing size of people is having othereffects. One airline has introduced a policythat larger persons pay for two seats; hospitalshave had to purchase larger beds, biggercommodes, and wider wheelchairs for theirpatients, and finally, with death, comes biggercoffins and wider burial plots.

Clothes sizes are going up: in 2000, Marksand Spencer relabelled its women’s size 14as size 12. Children’s clothes now have to bemade in larger sizes.

On the other hand…Some insist that obesity is neither a disease,nor does it necessarily signify poor health. A portly but fit person may well be healthierthan somebody who is slim but inactive. Theexact amount of ill-health attributable to obesityis not certain.

Others argue that we are unnecessarilyobsessed with weight, driven by commercialinterests keen to exploit a popular desire to bethin. Finally, many people are ‘happy to be fat’.

SIZE MATTERS FASTFACTThe demandfor ready-meals in theUK grew by

44%between 1990and 2002.

Does it matter?The medical consensus is that obesity hasserious implications for health. It is associatedwith increased risk for a variety of disorders,including type 2 diabetes, high blood pressure,stroke, heart disease and cancer (Figure 1).

It can also impact on quality of life (infertility,mobility problems and sleep disorders). And it can have psychological consequences,such as lowered self-esteem, anxiety andclinical depression – though, arguably, thesemay be more related to the social stigmaattached to obesity than obesity itself.

In the USA, the Centers for Disease Controland Prevention have said that obesity isclosing in on smoking as the mostimportant cause of premature death.

And it is not just a personal issue. Theeconomic costs are substantial, with recentestimates suggesting that between 2 and 8per cent of sick care costs in Western countriesare attributable to obesity – an amountcomparable to that spent on cancer therapy.

FIGURE 1: MAJOR HEALTH RISKSASSOCIATED WITH OBESITY.

JANUARY 2005 | 3

Why is obesity bad for you? How does it cause diabetes or increase the risk of cancer? Find out at Big Picture Online

www.wellcome.ac.uk/bigpicture/obesity

The energy content of food is usuallyexpressed in kilojoules (kJ). These units aresuperseding the former term, the calorie.

Different parts of food have differentenergy densities:

Because of its high energy density, fat is anexcellent way of storing energy in the body.

The people in Englandare getting fatter...

...and that’s not good news for their health

0

5

% of English population

10

15

20

25

1980 1993 2000 2002

0

1

2

Relative risk

Body mass index

3

4

5

6

21 22 23 24 25 26 27 28 29 30

Diabetes

Women

Women

Men

MenHeart disease

THE INCREASING SIZE OF PEOPLEMEANS BIGGER COFFINS ARE NEEDED.Rex Features

The media have also fuelled the currentnear-hysteria about obesity. The ‘obesitytimebomb’ makes for good headlines, andthere is a strong human interest angle thatcan sell newspapers. Why has it suddenlybecome an issue? In 1966, when the USPublic Health Service declared obesity amajor health problem, it passed unnoticed.

Yet the media’s ‘war on obesity’ presentsmany difficulties. Newspapers want toincrease sales, and that can lead tosensationalism at the expense of accuracy.The media promote slimness predominantlyin terms of beauty, rather than as a routeto long-term health.

Also, demonising obesity may actually becounterproductive – encouraging feelingsof inadequacy or unhappiness that maywell affect eating patterns. Promotingunrealistic body forms as desirable couldhave a similar impact.

The stereotyped view is that fat people eatcakes and crisps all day – they are greedy,slothful and lack self-control. We are hookedon appearances, but are the media to blame?

Images in newspapers, magazines andtelevision glorify slimness. Rake-thincelebrities like Kate Moss and VictoriaBeckham exude glamour. Gossipmagazines marvel at the svelte figures ofactresses and film stars, or their ability tolose weight after giving birth.

Fat is different. The media demonise flab.Celebrities with even a hint of fat are mockedfor appearing scantily clad on the beach.Few people manage to overcome fattism:comedian Dawn French is a rare exception.

OBESITY AND THE MEDIA

ENERGYWhat is obesity?How do we know if someone isoverweight or obese? The idealapproach would be to measure body fat levels directly. Unfortunately,this is hard to do without specialistequipment, so body mass index(BMI) tends to be assessed instead. BMI is easy to measure and is moreuseful than other simple measures(such as waist circumference, waist-hip ratio, skinfold measurements).

But BMI is best used as a guide to fat levels in the generalpopulation rather than in individuals.For instance, athletes typically havehigh BMIs despite having little bodyfat (muscle is heavier than fat). Also, ‘ideal’ BMI thresholds may nothold for young children, the elderly, or for people of different ethnicbackgrounds.

BMI

Underweight Less than 18.5

Normal range 18.5–24.9

Overweight 25–29.9

Obese >30

Percentage of the male (left) and female(right) population who are obese or severelyobese (dark shade).

Increased risk for two common diseasesas BMI increases.

Caution: Statistics usually hide as much as they reveal. For example, health risks increase at BMIless than 19. And in older people, higher BMI may be an advantage. More on this in Big Picture Online.

STATS CORNER

BACKGROUND

Carbohydrate:17 kJ/g

Fat: 38 kJ/gProtein: 17 kJ/g

Alcohol: 29kJ/g

4 | BIG PICTURE 1

The energy balanceThe number of calories we take in is offset by the numberwe use up. Anything left over is stored.

Energy (in)–

Energy (spent)=

Energy (stored)

In simple terms, people gain weight when they consume more energy than they use. Over time,the imbalance will lead to extra fat storage. How this plays out will differ between individuals, with environmental, physiological, pyschological and genetic factors all playing a part.

METABOLISM

HOW IT WORKS...

A fine balanceBody weight is a finely controlled system. We needto have enough stored energy to survive even if wemiss a meal or two, but not so much that we carrypounds of excess body fat.

Honed by millions of years of evolution, this systemis extraordinarily sophisticated. During a typical year,we consume around a million calories. Generally, our weight at the end of the year is fairly close towhat it was at the beginning – so the body hasbalanced energy intake and use to an accuracyof less than 1 per cent. This is far superior to ourattempts to consciously regulate calorie intake.

The key to this monitoring is a complex network ofchecks and balances, involving hormones and thenervous system, that regulates appetite, exerciseand rest, storage of energy, and cellular metabolism.We don’t fully understand how this system works,but it seems to create two important feedbackloops: if our weight drops, it promotes greaterintake of food; and if our weight goes up, it stimulateschanges that should drive weight down, such asspeeding up body metabolism.

Loss of weight is resisted by the body particularlypowerfully. This is thought to be an evolutionarysurvival mechanism, to ensure survival in times of famine. The brain automatically slows down thebody’s metabolic rate, reducing the number of calories burned. And, of course, we feel morehungry, so seek out food.

From this perspective, it is not surprising that most‘casual’ diets end in failure. It may not be a failure of will power but the automatic effect of an ancientsurvival mechanism.

The complex systems controlling body weight andenergy use are coordinated by the brain. Like allmetabolic systems, they can be disrupted, leadingto effects on weight. Some prescribed drugs (e.g.steroids and some antidepressants), for example,can cause weight gain as a side-effect.

LOSS OF WEIGHT IS RESISTED BY THEBODY PARTICULARLY POWERFULLY.

Weight-lowering

mechanismstriggered

Weightgoes up

Weightgoes down

Weightgoes up

Weightgoes down

Weight-raising

mechanismstriggered

Normalweight range

THE FEEDBACK LOOPS INVOLVED IN BALANCINGENERGY INTAKE AND USE.

Genetic influence1. Melanocortin receptor2. Leptin

Drug treatment1. Sibutramine2. Orlistat

Stomach anddigestive systemDigests food,absorbs fuel moleculesSignals fullness to brain

Fat tissueStores energySends signals to brain/body tissues (e.g. leptin)

ë Fullness’Che

ap, p

lent

iful,

ener

gy-r

ich

food A

dvertising, peer p

ressure etc.

Ene

rgy

use

Energy use

Monitors body’s energy levelsControls energy use

LiverGLYCOGEN

Mus

cle

GLY

CO

GE

N

Fat ti

ssue

TRIGLYCERIDE

FOOD INTAKE

Emotions

Energy Fullness

Reward pathways

THE BRAIN:Integrates signalsControls eating behaviour

ABOVECONTROL OF ENERGYINTAKE. INTERNAL(PHYSIOLOGICAL) ANDEXTERNAL FACTORSINFLUENCE OUR INTAKEOF ENERGY (EATING) AND USE OF ENERGY(METABOLISM ANDEXERCISE).

JANUARY 2005 | 5

‘Three-year-old dies of obesity’screamed the newspaper headlineswhen, in May 2004, a child died fromheart failure in a London hospital.She weighed a staggering 40 kg. A media frenzy erupted, and theparents were blamed for ‘stuffing her to death’.

Was it fair to accuse her parents?Scientists later confirmed that therewas a medical problem behind thechild’s extreme obesity: a genetic glitchthat triggered her immense appetite.

Genes play a crucial role in shapingour weight, but scientists have onlyrecently started to work out how. It is too simple to say that obesity is ‘all in the genes’ but our geneticinheritance does have a big say inour size.

Researchers can come at obesityfrom two directions. In a ‘classical’approach, the extent to which weight or obesity is inherited can be assessed. This is a difficult area to study, but the consensus is thatthere is a high degree of heritabilityin body weight.

Obesity genesA newer approach is to track downthe genes involved in obesity. Of course, no gene exists just to makepeople fat. But, on rare occasions,someone may inherit a mutation that leads to excess weight gain.The first evidence of this came froma very fat mouse.

These ‘ob’ (obese) mice weighalmost three times as much asnormal mice. They were found to

In 2002, a London team headed by Professor Steve Bloom caused much excitement when theyreported in the journal Nature that a molecule called PYY3-36 made rats less hungry; they ate lessand got thinner. The molecule even seemed to work on people, in a small clinical trial. But in 2004,another group reported that they could not get the same results with PYY3-36. What was goingon? And what does the dispute say about modern science? Find out at Big Picture Online.

www.wellcome.ac.uk/bigpicture/obesity

Obesity and genes

Adolphe Quetelet – a Belgian astronomer,meteorologist, sociologist, mathematician andstatistician – was the first statistician to use the normal distribution curve (used to measureerrors in astronomy) to model human variation.

The normal distribution curve takes the shape of a bell orhump of a camel. This reflects the fact that most scores (for height, weight, examination results, or whatever is beingmeasured in a population) cluster around the middle point (the top of the curve). Extreme values are far more infrequent,and are represented by the sides of the curve.

Quetelet used the normal distribution as a basis of his conceptof the ‘average man’, ‘l’homme moyen’ – the ideal from whommost of us deviate according to the normal distribution.

Quetelet also devised a measure of body mass, now known asQuetelet’s index, or the body mass index (BMI; see page 3).

FASTFACTYoung childrenwhose parentsare overweightare 13 to 15times morelikely tobecome obeseyoung adultsregardless ofthe child’scurrent weight.

Beyond leptinDigging deeper, scientists have now found more than a dozen genesthat, if mutated, may predisposepeople to obesity.

The gene for the melanocortinreceptor is a promising candidate,since around six per cent of youngchildren with severe obesity have thisgene disrupted. Five other geneticmutations that cause obesity inchildren have been pinpointed.

However, these are still rare cases,in which weight control has gonedrastically wrong. They are unlikelyto explain most individual differencesin weight gain in children and adults.

The likelihood is that there are asmall number of genes that have a major impact in a few cases, and a much larger number of genes(perhaps 200–300) that have smallereffects in a larger number of people.The genes could be involved in any part of the body’s complexmechanisms of weight regulation.Over time, even minor variationscould have a big impact on weight.

be missing a hormone, which wascalled leptin (from ‘leptos’, theGreek for ‘thin’). The defect wasdown to a mutation in the ob gene.

Mice without leptin had an insatiableappetite. But when leptin was injectedinto ob mice, they returned to normalin less than a month. Leptin thusappears to switch off hunger.

So much for mice: what abouthumans? In Cambridge, researchershad been referred two cousins whohad an intense drive to eat; they wereexceptionally obese. Sure enough,the children shared the same geneticmutation as the ob mice. Whengiven leptin, their appetite went downand they began to lose weight.

Leptin was instantly hailed as anobesity wonder drug. Butdisappointment soon followed. Most obese people do not lackleptin – quite the contrary. Theyhave even more than normal people,but the body does not seem torespond to it. So giving people leptindoes not help them lose weight.

GENES PLAY A CRUCIALROLE IN SHAPING OURWEIGHT

A FAMOUS BELGIAN Friend or foe?Fat gets a bad press. But fat has important biological roles. It is a way of storing energy. It also pads and protects ourorgans and helps us to keep warm. Fat molecules are needed tomake cell membranes and to transport vitamins around our body.

But excess body fat in the wrong place can be bad. Fat is laiddown to give two main body shapes – apple or pear. Men tendto be apples, women pears; as fat tissue around the abdomen is particularly strongly linked to health problems, men tend to be at greater risk than women. After the menopause, though,women tend to become apple-shaped, increasing their risk.

ABOVETHE OB MUTANTMOUSE (RIGHT)DWARFS ITSNORMALRELATIVES.J Friedman/J Bonner

ON THE WEB

6 | BIG PICTURE 1

The nature versus nurture debatehas raged for decades. For humancharacteristics, the choice has beenbetween ‘biological destiny’ (thenature part) or upbringing andenvironment (nurture).

So what exactly is ‘nature’ these days?These days it has come to mean ‘inour genes’ or, perhaps, ‘hard wired’into our brains: there is little we cando to change the outcome.

And ‘nurture’? This used to reflectthe way we were brought up, theway we were treated by our family,the values we learned as we grewup – all things that moulded ourbiology and could be altered. Nowwe have ‘the environment’, whichincludes things like peer groups,social pressures, pollution, infectionsand so – again, all factors outside us that may have a lasting impact.

Nowadays, very few people stick tosuch an either/or view of the world.

Crucially, the distinction betweennature and nurture – it’s either oneor the other – is rarely if ever true.

Most biological traits are influencedby both. Not only that, but they arealso bound up with one another: the influence of genes will dependon the environment and vice versa.

For obesity, the nature argumentsays that our size is governed byour genes. If we are destined to belarge, then large we will be. Thenurture viewpoint is that it is down to the food we consume and howmuch exercise we take – both thingswe can do something about.

Clearly, some cases of obesity aredue to nature. If you are unfortunateenough to inherit a mutation in yourleptin gene, it is almost certain thatyou will grow up to be obese.

On the other hand, if you are born ina poor urban area, your environmentwill greatly increase your chancesof becoming obese, whatevergenes you have.

Most of us sit somewhere in themiddle: our genes, acting throughcomplex biological processes,influence our size; so does theenvironment in which we are brought

up – the views of our parents, ourfriends and the availability of food.

So the whole situation is muchmore complex than sometimesportrayed. The effects of genes, for example, will often be quitesubtle. They may predispose to acondition or trait, but do not make it inevitable. Yes, eating less will lead to weight loss, but the body’sbiological response to this changecannot be ignored.

This is a complex network ofinteractions, which science is onlyjust beginning to untangle. Ourunderstanding of the bigger pictureis still far from complete.

Drug treatments target the biology of this network; health campaignsand political policies tackle theenvironmental contributions. Effectivelong-term solutions are going toneed to recognise the complicatedrelationships between these factors,and a host of genetic, psychological,social and political factors.

WEIGHTDEBATEThe nature versus nurture debate obscures importantpoints about complex human traits.

Raising the OBsThe Big Picture on Obesityonline activityAccess Raising the OBs atwww.wellcome.ac.uk/bigpicture/obesity

You have been given responsibilityfor looking after a young creature,an ‘OB’. Unfortunately, they have atendency to become obese. Evenworse, they have a mind of theirown. Can you rise to the challengeof raising a healthy OB and sodiscover the causes of their super-size problem?

This Big Picture on Obesity has anaccompanying web-based activity– The OBs. Your task is to parent ayoung creature as it grows, choosingits diet, managing its activity.

But beware: your OB may not be keen on tofu and salad andswimming 100 lengths beforebreakfast. And you may find lifethrowing a whole heap of toughchallenges at you.

Your OB comes with an inbuilt‘genetic inheritance’, which affectshow it interacts with you and itsenvironment. All these influenceswill impact on its final size.

After you’ve tried bringing up oneOB, you then get the chance toinvest resources to help all OBsstay healthy. What are you going to spend your money on? Geneticengineering? Combating poverty?OB parenting classes?

Teachers: The game will enable studentsto explore for themselves how genes,upbringing and environment affect weightgain. The game is designed to take aboutan hour of lesson time, and includes anoptional extension activity. The websiteincludes guidance for teachers.

This activity has been developed by theCentre for Science Education at SheffieldHallam University.

ONLINE ACTIVITY

www.wellcome.ac.uk/bigpicture/obesity

JANUARY 2005 | 7

Does society pressure people tobe a particular size and shape?Yes. Research shows that obese people applying for jobs are less likely to succeed – even if they areapplying to be a VDU [visual display unit] operator, in a back room, with no contact with the public.

Shouldn’t people be free to choosethe lifestyles they wish, even ifthey end up overweight or obese?Yes. But society and doctors also have aresponsibility to draw attention to unhealthy lifestylesand help people who want to improve their health torealize they can. At the moment we’re helping themmake unhealthy choices: high-fat foods and largerportions are the cheap options in supermarkets.

What do you think the keyfactors are in the growth of obesity?There are genetic factors, but changes inthe environment over the last few decadeshave been the crucial key. People areliving far more sedentary lifestyles thanthey did 20 or 40 years ago. There’s alsobeen a change in the kind of food we eat. Today we eat far more fat and refinedsugar. These foods are very palatable and therefore easy to over-consume.

Do you consider obesity to be a disease?It meets all the criteria for a disease. It shortens life,causes painful symptoms and other healthcomplications, and puts people at risk for otherdiseases. It’s certainly a public health problem.

How big a problem do you think theincreasing incidence of obesity is? Huge. If we stopped obesity the population would behealthier than it would be if everyone stopped smoking.

How much control do you thinkindividuals have over their ownshape and size? Is weight controljust down to self-control?If it was, we wouldn’t have the problem. This isn’tabout ever-increasing numbers of people showingless self-control. The problem is that when people tryand lose weight. They are fighting some of our mostfundamental biological processes.

To what extent is size ‘in the genes’?What does this mean? How do youthink genes exert their influence? A number of studies in the 1960s pointed to a veryhigh degree of heritability, of round 40 of 60 per cent.But obesity is rarely down to a single gene mutation.It tends to be caused by a number of genetic variantsthat come together and exert their influence indifferent ways – by increasing energy intake, decreasingexpenditure, or prompting the body to store energyas fat rather than muscle. However, environment stillplays a critical role: if there’s no food available, themutations won’t be able to exert their influence.

Who do you think should takeresponsibility? All of us. Obese people should take responsibility for themselves. Employers should provide a workenvironment that protects people against obesity byoffering exercise facilities, and bowls of fruit insteadof biscuits at meetings. The government shouldensure that supermarkets sell healthy foods and labelthe nutritional content clearly. And the medicalprofession needs to be proactive in helping people to recognise they are getting obese, explaining therisks, and offering prevention programmes.

Which are the key organizations in obesity research, support and medicine? Find out at Big Picture Online

www.wellcome.ac.uk/bigpicture/obesity

You can protect yourself by being physicallyactive, even if you are obese. Sumowrestlers have huge amounts of excessweight, but a lot of this is muscle with fatoutside the abdomen. However, when theyretire, fat is deposited inside their abdomensand becomes more dangerous.

REAL VOICESThe doctorNick Finer is a researcher and Honorary Consultant in Obesity Medicine at Addenbrooke’s Hospital, Cambridge. We asked him for a doctor’s perspective on obesity.

Yes, they should. Obese people are 20–30 timesmore likely to develop type 2 diabetes – and havea two to threefold increased risk of cardiovasculardisease. Cancers of the breast, uterus, colon and prostate are also linked to obesity.

SHOULD OVERWEIGHT/OBESE

PEOPLE HAVE CONCERNS ABOUT

THEIR FUTURE HEALTH

Rex

Fea

ture

s

Why are we getting fatter? The simple answer is that we are consuming too much and exercisingtoo little. Our modern lifestyles are bringing us into conflict with our ancient metabolism.

WEIGHT GAIN

FASTFACTA 20-year-oldobese mancan expect to live

13 yearsless than the average.

FASTFACTYou onlyneed to eat200 extracalories a day (aboutthree digestivebiscuits) over a year toput on 10kgby the end of the year.

The fitness and slimmingindustries promote the idea thatbeing overweight is a bad thing andshould be remedied. While this canlead to health benefits, weight loss is generally promoted for ‘beauty’rather than health reasons.

The pharmaceutical industrybenefits from obesity beingrecognised as a medical problem as it can market drugs to tackle it. In 2002, the market for anti-obesitydrugs reached $520 million (£270 million) in the USA, Europeand Japan. Most analysts believethis will be a multibillion dollarindustry within a decade.

All of these depend on a desire forweight loss, so keeping body weightin the public’s eye is to their advantage.

Supermarkets have been blamedfor a pricing structure that makesunhealthy food cheaper than healthyfood, and for placing unhealthyfoods in high profile positions (suchas having sweets near checkouts).Food industry sponsorship ofschoolbooks and sports has alsobeen widely criticised.

The advertising industry is anotherforce influencing obesity. Millionsof pounds are spent encouraging us to consume energy-dense food anddrinks – often specifically targetingchildren. The money spent promotingfruit is a tiny fraction of that spent onadvertising sweets and snacks.

Money talksFood producers, distributors andadvertisers have all been blamed for obesity, particularly in children.Others, such as the slimming, fitnessand pharmaceutical industries,benefit from the problem.

Food producers need to sell their products to survive. But manyof their products are high in fat andhidden sugar. The industry is accusedof producing too many sweetenedand processed convenience items,and of poor food labelling thathinders consumer ability to choosehealthy options.

In 2002 a very overweight man filed a lawsuit against several USfast-food chains, claiming these had contributed to his obesity. Fast-food chains have been tickedoff for ‘super-sizing’ and encouragingcollection of free gifts.

MILLIONS OF POUNDS ARESPENT ENCOURAGING USTO CONSUME ENERGY-DENSE FOOD AND DRINKS

ACTIVITYGOES DOWN...

8 | BIG PICTURE 1

RIGHTMANY FACTORS ARECAUSING US TO LEADLESS ACTIVE LIVES ANDTAKE IN TOO MUCHENERGY.

Computergames...

Car culture...

Labour-savingdevices...

Busy lives... Fizzy drinks...

Fast food...

Energy-richfood...

Television... Less PE..

JANUARY 2005 | 9

Is obesity only a problem in the rich Western world? Absolutely not. Find outabout the impact of obesity in the developing world at Big Picture Online

www.wellcome.ac.uk/bigpicture/obesity

Psychological factors undoubtedlyinfluence eating and exercise habits,and hence weight.

Eating is not only necessary butenjoyable. Research has shown thateating carbohydrates boosts levels ofserotonin and endorphins in the brain,producing feelings of pleasure. Theseare part of ‘reward pathways’ in thebrain that encourage us to do thingsthat we have gained from in the past.

The reward pathways may drive us to one course of action, but we alsohave brain systems that can over-ridethem. These include signals from the ‘thinking’ areas of the brain, thefrontal cortex. So we can delay afeeling of reward in favour of a longer-term goal. This psychologicalmechanism is known as ‘delayedgratification’. We may save now inorder to enjoy a relaxed retirement.

But it appears that we are not actually very good at delayed gratification. In experiments in which subjects areoffered a reward immediately or abigger reward later, most people go for the immediate benefit. We are,

perhaps, not as logical in our decisionmaking as we might think. Forgoing a cream cake in order to be slim latermay not be in our make up.

Research also suggests socio-economic factors are important. In the UK, women from the poorestareas now have almost twice the riskof obesity as women in richest groups.

Some social scientists suggest thatfamilies in higher socio-economicgroups have a greater sense of controlover their environment, which helpsthem take longer-term views. This may extend to a greater emphasis on maintaining health, for example by eating more balanced diets.

Such views are supported by a recentstudy of 1200 teenagers in the north ofEngland. Students from more affluentfamilies had the highest level of dietaryrestraint, and used more healthyweight control methods.

The less well off, on the other hand,opt for more immediate pleasures –perhaps, given their circumstances,less able to imagine distant benefits.

TEMPTATION: FAST FOOD IS EASY TO FIND IN POOR AREAS OF THE UK.

CONSUMPTIONGOES UP...

EXAMPLES OF ENERGY USE

1 HOUR OFTHIS ACTIVITY

THIS MUCHFOOD*

=

=

=

=

ON THE WEB

GRATIFICATION

Money matters There is a clear north-south divide in lifeexpectancy in the UK. According to a 2001analysis by the Office of National Statistics,those who live longest live in the southwest,southeast and east of England.

There is an inverse relationship betweenpoverty and life expectancy: the pooreryou are, the sooner you are likely to die.Obesity is also more common in poorerparts of the country. This is a strangereversal – it used to be the rich who grewfat while the poor starved.

Researchers have found that people on low incomes eat the least amount of fruitand vegetables. Households on lowerincomes consume much more full-fat milk,soft drinks and more white bread thanwealthier ones. Working class women aremore likely to be obese than those in themiddle or upper classes.

One problem is the availability of fruit andvegetables. Many poor neighbourhoodsonly have small shops, which offer a limitedrange of food, sometimes at higher pricesthan big supermarkets. Some of Britain’spoorest areas are known as ‘retail deserts’they have so few food shops.

The upshot is that the poorer you are, theless you get for your money. At the sametime, fast food outlets are cropping upeverywhere. Convenience food is cheapand filling, and children like it. For a singleparent on a low income, juggling family andjob, the attraction of ready-made meals andtake-away menus is obvious.

The wealthy, by contrast, have the money to buy healthy food and join health clubs.And they will probably have friends from asimilar background, with similar ideas aboutweight and healthy eating.

With daily life providing less opportunity toburn calories, people increasingly need toplan specifically for exercise – somethingthat generally requires time and money.

=

*Approximately!

Food at leisure venues...

Mass marketing...

10 | BIG PICTURE 1

Healthy lifestyles One way to tackle obesity is by promoting healthierlifestyles. To date, there has been no public healtheducation campaign directly aimed at reducing obesitythrough nutritional changes, or by any other means.

Although campaigns promoting healthy lifestyles are alreadyin place – 30 minutes of physical activity, five times aweek, and the ‘five a day’ fruit and vegetable campaign– they are unlikely to tackle the obesity issue. Campaignfigures show that only just over a third of men, and aquarter of women, meet the physical activity targets.

With one third of adults and half of all childrenpredicted to be obese by 2020, health educationcampaigners are trying to get the importance of ahealthy lifestyle message across early, by targetingnutrition and physical activity in schools.

But it is still debated how effective public health campaignsactually are. There is very little evidence that they work.Shifting people’s behaviour is usually very difficult.

Diets ‘Dieting’ is defined as any attempt to achieve or maintainlower body weight by limiting the amount or manipulatingthe type of food eaten.

The promotion of diets and diet products is bigbusiness. In 2002 the annual revenue for the US weight-loss industry was $39 billion (£20 billion). The subsequentrise in industry profits has been mirrored by rising obesityrates, suggesting the only pounds being lost are fromthe dieter’s wallet.

‘Calorie control’ lies at the heart of most diets.Successful diets focus on slow achievable weight loss.

To maintain a lower body weight, changes in dietand lifestyle must be continued indefinitely.Unfortunately, many diets only focus on short-termweight loss rather than weight-loss maintenance.

It is also important to diet sensibly, as some diets canthemselves lead to health problems. Obese patientsundergoing medical treatment generally follow calorie-controlled but balanced diets, which are combined withother forms of help, such as emotional support andexercise programmes.

Many diets are successful, but maintaining lower weight over the long term can be very difficult.

BEATING THEBULGE So losing weight just means eating less

and exercising more. Simple? Far from it...

TO DATE, THERE HAS BEEN NO PUBLICHEALTH EDUCATION CAMPAIGN DIRECTLYAIMED AT REDUCING OBESITY.

SURGICAL INTERVENTIONS

The most common operation is now the use of an inflatable band that can be inserted through keyhole surgery andrestricts stomach size to 15–20 ml. Evengreater weight loss can be achieved bymore complex procedures that restrictstomach capacity and change the flow of food through the intestines.

FASTFACTThe increasein weight ofthe averageAmerican from1990 to 2000(4.5 kg) causedaircraft to burn350 millionmore gallonsof fuel at anannual cost of$275 millionper year.

Oesophagus

Pouch

Stomach

Reservoir

Inflatableband

Small intestine

JANUARY 2005 | 11

DrugsThere’s no such thing as a magicweight-loss pill. Drugs that do workhave to be taken long term, just like agents used to control bloodpressure or cholesterol levels.Weight-lowering prescription drugsare available in the UK, but, like alldrugs, may have side-effects thatneed to be weighed against theirpotential benefits.

The two most commonly used aresibutramine and orlistat (Xenical).Sibutramine acts on the brain,making a person feel full sooner or for longer, while orlistat reducesfat absorption in the gut.

They are only prescribed to obese people who have failed tolose weight after changing dietand lifestyle. They can’t be givenfor long, and users need advice ondiet and exercise and regular weightand blood pressure checks.

Other drugs, or combinations ofdrugs, have been used in the USA in the past – but serious side-effectsmeant that some of these have nowbeen withdrawn. Clearly there’s ademand for weight-lowering drugs,and many companies are developingnew ones.

One promising new drug, rimonabant,seems both to reduce the cravingfor food and help people stopsmoking, by acting on a particularclass of cannabinoid receptors inthe brain. (These receptors respondto the psychoactive component ofcannabis, chemicals known ascannabinoids. It was noticed thatsmoking cannabis caused ‘themunchies’, and this led to a searchfor drugs that block cannabinoidreceptors and reduce appetite.)

The next few years are likely to seemany more products hit the market,targeting different points in thebody’s weight control system.

Find out more on pharmacologicalapproaches at Big Picture Online(www.wellcome.ac.uk/bigpicture/obesity).

Going to extremes The desire to be slimmer has led many to turn tounorthodox ways of losing weight. The desire to makemoney has led many to provide ‘miracle cures’.

So-called fad diets abound. The cabbage-soup dietand grapefruit diet are fairly self-explanatory. Otherscome with a supposed medical endorsement. Currentlypopular (if controversial) is the Atkins diet, and other low-carbohydrate diets. While these can work over the shortterm, their long-term effectiveness is unclear and thereare concerns about their longer-term impact on health.

As well as diets, some worried parents send theiroverweight children to fat camps, or even join campsthemselves. They hope they’ll receive supervision andmotivation that will help them reduce their weight. Butkeeping the motivation up once back home can be tough.

Liposuction, sucking out fat using special surgicalequipment, is a more drastic way to remove excess fat.But it is a cosmetic procedure that can only remove fat from under the skin, rather than the more unhealthyfat within the abdomen. Plastic surgeons only use it to discard stubborn ‘blocks’ of fat rather than use it tosubstitute for diet and exercise. There is no evidence itoffers long-term health benefits.

The famous Roman rhetorician ClaudiusAelian (170–235 CE) described in hisHistorical Miscellany how, in Ancient Greece,Dionysius, the ruler of Heraclea, hadbecome so obese he suffered difficultybreathing. As a cure, his doctors pushedlong, thin needles through his hips and bellywhilst he was in a deep sleep. The treatmentfailed: after choking to death from his fat, Dionysius could hardly be moved to his grave.

Another classical treatise, Sushrita Samhita,part of traditional Indian Ayurvedic medicine,describes the use of guggul – a yellowishresin produced by the thorny mukul myrrhtree for obesity. More recently, trials haveshown that an extract from guggul lowerscholesterol levels.

Gold is another classical remedy with along history. Over 5000 years ago, theEgyptians ingested gold for mental, bodilyand spiritual purification. In 1965 DoctorsNilo Cairo and A Brinckmann wrote a best-selling work entitled ‘Materia Medica’,in which colloidal gold – metallic golddivided into fine particles and suspendedin solution – was listed as the number oneremedy against obesity.

DIETINGIn the 1860s, London undertaker WilliamBanting found he could successfully loseweight by eliminating sugar, starch, rootvegetables and pork from his diet. Hisbest-selling book, Letter on Corpulence,urged people to adopt a low-carbohydrate,high-protein diet – and ‘Banting’ became a

popular weight-loss strategy in America.

In 1890, Horace Fletcher advocatedchewing every mouthful a hundred timesuntil it turned to liquid and ‘swalloweditself’. This prolonged chewing becameknown as ‘Fletcherizing’ – and Fletcherhimself as ‘the Great Masticator’.

John Harvey Kellogg, a devotee ofFletcherizing, invented a ‘Chewing Song’for patrons at his nutritional sanatorium inBattle Creek, Michigan. Kellogg alsopromoted vegetarianism and, unsurprisingly,a diet rich in his own invented cereals.

Dr Robert Atkins introduced his controversialhigh-protein diet in 1972. This then took a back seat to a series of low-fat, high-carbohydrate diets, such as the DeanOrnish programme and the Pritikin diet,over the next three decades.

The mid-1990s saw the carbohydratebacklash, with the arrival of Barry Sears’‘The Zone’ plan and other sugar-bustingdiets. And by the early 2000s, Atkins wasback with a vengeance.

Ultimately, most diets are simply carefullypackaged ways to encourage people to eat less, usually by restricting the range of food that can be eaten. One drawback,however, is that by focusing the mind onweight loss and on what cannot be eaten,they may actually make it harder for us toresist temptation.

THERE’S NO SUCH THINGAS A MAGICWEIGHT-LOSS PILL

FASTFACTWimbledon’sseats are 6cmwider thanthe original1922 models.

A POTTED HISTORY OF ANTI-OBESITY TREATMENTS

12 | BIG PICTURE 1

How important is your size to you?Vicki Swinden Not even slightly. But for 40 years Ispent every waking hour worrying about how I couldlose weight and feeling a failure because I couldn’tcontrol it.

Now I’m very careful with the messages I give mychildren. I never say, ‘you can’t eat that’, because ifyou restrict someone, they want it even more. Thefridge is 98 per cent full of fresh food, but if we want(for example) a McDonalds every now and then, we’ll have it.

Louise Diss More important than it should be. I sometimes judge myself more on how fat I feel,regardless of my actual size.

How do you feel others perceive you?VS On the street, people have been verbally andphysically obscene. I’ve been spat at. On the busesand tube people say ‘don’t sit next to me’. In thesupermarkets, they say, ‘you shouldn’t have that inyour shopping basket, that’s why you’re so fat’.

The Fat is the New Black website has had enormousresponse. Some has been good – some horrendous. People feel it’s OK to write to me and call me greedy,disgusting, ugly, lazy, and a drain on the NHS. Aftermy last Radio 2 interview, I got an email from a girlon the point of suicide. People want to die becauseof the pressure our nation puts on them.

LD As an adult I was intimidated by groups of teenage kids, who said things like, ‘Fat bitch, what do you think you’redoing on this side of the street?’

One particular group threw stones at my window. I had to tell the police in the end and they were cautioned.

REAL VOICESWhat’s it really like to be obese?We spoke to two people with experience – Vicki Swinden, who runs a size acceptance group,and Louise Diss, who has struggled with herweight for many years.

Do you worry about your futurehealth? What do you think therisks are?VS No, I think I’m in the best shape ever and I’mimproving by the day. I feel very positive about myfuture health. I eat a very healthy diet and take lots of exercise.

LD I do worry. I want to be healthy when I’m old. I especially worry about my bones goingand getting arthritis in my knees.

How much pressure do you feel tobe a particular size and shape?VS The ‘advertised world’ puts pressure on us all to conform to a certain ideal.

LD I have a husband and two children who loveme for who I am. But people do feel able tocomment. At college I once bought chips and astudent on my course, said, ‘You’re not going toeat those are you?’ After I lost weight, someoneelse said, ‘You’re more credible now’. I find thatamazing – I’m still the same person!

LD Research shows that people thinkobese people are less intelligent:they’re often portrayed as buffoons in films and plays. They’re neverportrayed as the sex goddess.

HOW DO YOU THINK

SOCIETY TREATS/VIEWS THE

OVERWEIGHT AND OBESE?

MONTY PYTHON’SMR CREOSOTE:PORTRAYED AS AGLUTTON UNABLETO CONTROL HIS EATING, HE EVENTUALLYEXPLODES.Kobal Collection

JANUARY 2005 | 13

Do you diet? What diets have youtried? Did they work?VS I have tried every diet on the market includingslimming pills, food substitutes and meal replacements– they all ‘work’ and on one I lost pounds in weight.Never once has the weight loss been maintained andI believe this is because ‘the whole picture’ was notbeing dealt with. My dieting is more advantageous tothe Diet Industry than it is to me.

LD Over the years I’ve tried everything, includingthe cabbage soup diet, hard-boiled egg diet,slimming gum containing amphetamines andmeal replacements.

They all concentrated on the wrong thing – food.But food isn’t the issue. The best diet is to lookat what’s going on psychologically. One day itclicked that I wasn’t taking care of myself. If I feltlow – if I walked past a group of teenagers andthey said something – then I would buy a creambun to feel better.

To break that cycle I needed to look at my wholeself – mind, body, work, home – and find a level of contentment that didn’t involve food. Once I didthat I was able to lose six stone and keep it off.

What do you think should be done about it, if anything?VS I find the debate going on now very scary. We’re telling obese people that they’re wasting NHS time and resources. They already feel unworthy– now they feel they can’t go to their GP. I can’t seethe problem getting better, if that’s the way it’s dealtwith. People don’t work well if they’re criticised: they need encouragement, congratulations andpositive feedback.

LD It’s too big a problem for a quick answer.Sensible foods should be advertised and sold (at the moment you can advertise chocolatealthough you can’t advertise cigarettes). Peopleshould be helped to get their weight down in a healthy way. We need to aim for a nation ofpeople who are able to not rely on food, drugsand alcohol to fulfil a need.

Why do you think you are the shapeyou are? Do you think it is writtenin your genes? Or your metabolism?VS There are definitely genetic factors. My motherand grandmother were big, they have the same hairand skin as me – I was never going to be 8 stone.

There are also psychological factors. When I wasfour years old, someone commented to my mumthat I was fat and she started monitoring my food. I don’t blame her, she tried to do what was right.

LD I don’t think it’s my genes. I have sevenbrothers and sisters, some of them are overweight,but I am the only one who has been grosslyoverweight.

I think a lot is environmental. I grew up on a farm,where there was lots of physical work like potatopicking to be done. I was also a county swimmer,so I was very fit. When I left home I had aninactive job, and because I was on a low income,I ate cheap food like chocolate, which provided a quick fix – and the pounds gradually piled on.

Who do you think should take responsibility?VS All of us, man, woman, child, local and nationalgovernments and the media.

LD Adults need to take responsibility forthemselves. When it comes to children, parents,the government, the food industry and marketingneed to take responsibility.

Vicki Swinden runs Fat is the New Black, asize acceptance group which she founded tocounter the public’s negative attitude towardsobese people. www.fatisthenewblack.com

Louise Diss is a social worker and an obesitycounsellor for The Obesity Awareness andSolutions Trust (TOAST). TOAST is a nationalcharity dedicated to encouraging a betterunderstanding of obesity, its causes and thepractical solutions that are or should be available.www.toast-uk.org.uk

HOW COMFORTABLE ARE YOU WITH YOUR CURRENT SIZE? WOULD YOU PREFER TO BE SLIMMER?

VS A friend who’d had an implant in her stomach to stop her eating,offered to pay for me to have thesame surgery (the operation costsseveral thousand pounds). I said, ‘No,I don’t want it in a million years. One,it’s invasive. Two, it’s not a priority.’

VS I don’t know. It’s used as too muchof a catch-all word.

LD Yes. It’s one of the biggestdiseases of the last few decades and getting bigger. It’s an epidemic.

DO YOU CONSIDER

OBESITY TO BE A DISEASE?

14 | BIG PICTURE 1

WHOSERESPONSIBILITY?

If we are going to halt the trend towards obesity,something needs to change. Is it just up to us tolook after ourselves better, or do others need totake responsibility to make it happen?

IndividualsIs weight control just up to us and our will power?

We may instinctively feel that aperson’s lifestyle is a matter ofpersonal choice. But:

• Temptation: Cheap, widelyavailable food.

• Life pressures: Too busy to eatproperly or exercise.

• A genetic legacy: Strongevolutionary pressures drive us to eat for survival.

Whatever the causes, it appears thatrelying on individual self-restraint isnot an effective strategy for a healthypopulation.

ParentsShouldn’t parents take the lead?

One US doctor described the surgein childhood obesity as ‘child abuse’.Surveys in the USA and UK indicatethat people think parents have theprimary responsibility for their children’sdiet. So what is going wrong?

• Temptation: Youngsters are facedwith many opportunities to indulge.

• Immaturity: A child’s brain is also less able to imagine, or beinfluenced by, the consequencesof their actions – so will be lessdeterred by fears of future healthproblems.

• Pester power: Constant pressureon parents.

Many have argued that marketing offattening products to children shouldbe minimised or banned, to providesupport for parents.

Schools/educationIs obesity an issue for schools?

Schools have a ‘duty of care’ toprotect and support young people.They can help children ‘choosehealth’, encouraging sensible eatingand exercise.

• Healthy eating schemes: Morebalanced school lunches; fruittuck-shops, breakfast clubs, andthe inclusion of healthy snacks andbottled water, alongside chocolate,in school vending machines.

• Teaching: About the nutritionalcontent of food, plus planning andpreparing healthy meals.

• Activity: Some schools haveextended the school day in order toaccommodate the Government’srecommended ‘two hours ofphysical activity a week’ plan.

• Sport: Aerobics and swimmingmay help pupils put off bytraditional ‘team games’ to find aform of physical activity they enjoy.

? ? ?

THE STATE WE’RE IN

How big a role do we want the stateto play in our lives? This is a deeplypolitical issue: some would arguefor little political intervention inbusiness or people’s personal lives;others would see the state taking amore active role.

When decisions impact so directlyon people’s choices, regulation canseem to be denying us freedoms.Some talk in terms of a ‘nannystate’ – where there is a high

degree of government intervention,because the state (the ‘nanny’)knows best.

DO WE WANT ONE?Apparently we do. According to arecent survey by the King’s Fund,three quarters of people in the UKwant stricter legislation to preventpeople from smoking and eatingunhealthily. This could mean laws to ban smoking in public places, or ‘fat taxes’.

But we want the best of bothworlds. Surveys show that while we support legislation in theory, we often oppose it when it impacts on our own lives. We argue for ‘civil liberties’ and ‘personal rights’.We resent governments poking their noses into our business.

DAMNED IF YOU DO...On the other hand, if thegovernment fails to act, this leaveschildren exposed to exploitative

FASTFACTNearly

6 timesas manyFilipinowomen areoverweightand obesetoday as theywere 20 yearsago (up from 6 per cent to 35 per cent).

Get

ty

Kob

al C

olle

ctio

n

Rex

Fea

ture

s

JANUARY 2005 | 15

IndustryShould the food industry show more concern?

The food industry spent £727 millionadvertising ‘food, soft drinks andchain restaurants’ in 2003 – morethan 60 times the entire annual budgetof the NHS Health DevelopmentAgency. Is this where action is needed?

• Regulation: The industry resistsattempts at greater regulation,arguing that adults can make theirown decisions about what they eat and that sedentary lifestylesare the main problem.

• Changing practice: McDonaldshas phased out its ‘Supersize’meals in the USA, and is beginningto offer ‘healthier options’. Onesweet maker has announced theend of the ‘king-size’ chocolatebar (though only by dividing it intotwo bars).

• Children: The industry saysadvertising is designed to increasebrand loyalty, not increaseconsumption.

• Tactics: Some observers havecriticised the industry’s politicallobbying activities, to influencegovernment policies and therecommendations of bodies suchas the World Health Organisation.

The Food Standards Agency hascalled upon the food industry towork collaboratively to recognise thepublic health impact of the productsit sells, and to consider what it coulddo to address it.

GovernmentIs the problem serious enoughfor Government action?

Obesity is now considered a ‘publichealth’ problem. As well as harmingmany individuals, it has economicconsequences (time off work, sickpay, healthcare costs). The House of Commons Health Committeecalled for action in two areas:

Lower calorie intake:• Food labelling: To show clearly

whether food is high or low incalories.

• Food advertising: A restriction on advertising aimed at children.

• ‘Fat tax’: On high-calorie foods.

Physical activity:• Urban planning: To support

pedestrians.

• Sport: Promotion of sportingactivities.

? ?

advertising and easy access tounhealthy foods. Shouldn’t weprotect the vulnerable?

And obesity is not just a personalissue. It is now also a public healthproblem. Obesity-related illnesssoaks up healthcare resources that could be used elsewhere.

Does this justify governmentinterference in our daily lives?Punishments or incentives?Education or coercion?

Hands up who can say ‘no’ to pizza, pudding,chips or cheesecake. Few of us can genuinelyresist them, yet if you think about it, thesefoods are wholly unnatural. So why are we soattracted to them?

Perhaps the answer lies with our hunter-gatherer ancestors. Their diet would have beenmostly fibrous wild vegetables, nuts and fruits.Occasionally, they would have feasted on woollymammoth meat, bison bone marrow, and wildfowl. There was plenty of protein and fat in theirdiets but always with hefty doses of fibre fromfruit and roots.

Our modern diet is packed full of carbohydrateslargely from processed cereals and refinedsugar. From the evolutionary perspective, thistype of food is relatively new. Carbohydratesfrom grains and cereals came in around 12 000years ago when agriculture and farming began.

As well as this rich harvest, agriculturalbreeding and intensive rearing practices havegiven us greatly increased access to meat.

Human society has changed with extraordinaryspeed – but our genes are more or less the sameas those we had when we trod the Africansavannah. So some argue that we are adaptedto a diet with plenty of meat fat, low incarbohydrates, and generous helpings ofseeds, fruit and vegetables.

As a result, we will always struggle against theattraction of high-calorie foods. It is our geneticlegacy. For hunter-gatherers, reality was oftengrim: food was not always abundant, theyswung from feast to famine. As a result,humans would have evolved to crave energy-rich foods, which they could store in their bodiesas fat as a life insurance for times of foodshortages.

Yet we now live in a society where food isplentiful. This is a time of big food and littleexercise – a lifestyle that is at odds with ourgenetic legacy.

HUNTER-GATHERERGENES?

Is obesity a disease? Who says so? And when does it become a public health as well as a personal issue? Explore the issues at Big Picture Online

www.wellcome.ac.uk/bigpicture/obesityON THE WEB

Rex

Fea

ture

s

SP

L

16 | BIG PICTURE 1 JANUARY 2005

• We are living a highly ‘obesogenic’ environment:energy-rich food is cheap, plentiful and highlypalatable; modern lifestyles require little energyexpenditure.

• Huge amounts of money are spent advertisingand promoting energy-rich products.

• Overweight people suffer stereotyping and arewidely discriminated against; this may causeemotional distress and comfort eating.

• Weight-loss courses can work, when calorie-controlled diets are combined with exerciseprogrammes, behavioural advice, and emotionalsupport.

• Pharmaceutical and/or surgical approachesare available when dietary/exerciseapproaches are not working, but they may have serious side-effects.

OBESITY: THE BIG PICTURE• Obesity is a growing personal and public health

problem in wealthy countries, and increasingly indeveloping nations.

• Obesity is linked to a number of diseases, such as increased risk of diabetes, heart disease andcancer.

• There is disagreement about the full extent of thehealth impact of obesity; some effects may be due to unfitness rather than obesity itself.

• Weight gain arises when the amount of energytaken in as food is greater than the amount burnedoff by activity and the body’s metabolism.

• Body weight is influenced by a wide range ofgenetic, metabolic, prenatal, psychological andenvironmental factors.

• A network of checks and balances involving ourhormonal and nervous systems attempts to keepour weight within a relatively narrow range.

• Weight loss usually triggers mechanisms that promote additional food intake and weight gain.

Additionally, teachers can order a class set of two copies or morefor students.

Order sets of a specific issue or subscribe to receive copies of each issue until further notice.

Order 10 or more copies andreceive an additional posterspecific to this issue.

Class-set prices2–20 copies: £1.00 per copy per issue (inc. P&P in the UK)

>20 copies: £0.75 per copy per issue (inc. P&P in the UK)

Postage and packing chargesUK – free of charge

EU – £0.15 extra per copy ordered

Rest of world – £0.30 extra per copy ordered

Other interested groups can alsoorder copies at these prices.

Payment methodsWe accept cheques, and all majorcredit cards and debit cards.

ContactSee www.wellcome.ac.uk/bigpicturefor full details, or:T +44 (0)20 7611 8651E publishing@wellcome.ac.uk

Or write to:Big Picture seriesThe Wellcome TrustFREEPOSTANG 6754Ely CB7 4YE.

LabNotes recipientsIf you previously received a copy of LabNotes you will continue toget a single free copy of each issuein the Big Picture series.

Like its predecessor, LabNotes, individual copies of each issue in the Big Picture series areavailable free for teachers and other educationprofessionals, or anyone with a professionalinterest in the topic.

To order an individual copy of a specific issue, or subscribe to receive a copy of each issue in the series, sign up atwww.wellcome.ac.uk/bigpicture/order.

BIG PICTURE SUBSCRIPTIONS