What Is Nutrition?

-The study of how your body uses the food that you eat.

What is a NutrientA nutrient is a chemical

substance in food that helps maintain the body. Some provide energy. All help build cells and tissues, regulate bodily processes such as breathing. No single food supplies all the nutrients the body needs to function.

Vitamins Minerals Water ProteinCarbohydrates

SugarsStarches

Cellulose

Fats

Variables which affect nutrient needs:

1. Age

2. Gender

3. Activity Level

4. Climate

5. Health

6. State of nutrition

Aim for Fitness

1. Aim for a healthy weight

2. Be physically active each day

Build a Healthy Base

3. Let the pyramid guide your choices

4. Choose a variety of grains daily, especially whole grains

5. Choose a variety of fruits and vegetables daily.

6. Keep food safe to eat.

Choose Sensibly7. Choose a diet that is low in

saturated fat and cholesterol and moderate in total fat 8. Choose beverages and foods to moderate your intake of sugars9. Choose and prepare food with less salt

10. If you drink alcoholic beverages do so in moderation

Energy Values of Foods & Nutrients; Obesity; Rules for

Achieving Desirable Weight

Chapter 1

Energy• The capacity to do work• Exist in various forms, each of which may be converted

into any other forms; heat, light, motion, sound and electricity being form of energy.

• To measure the amount of energy in any of its forms, it is ordinarily converted to heat energy and expressed in calories(kcal).

• Kilocalorie is defined as the amount of heat required to raise the temperature of 1 kilogram (kg) (2.2lb) of water 1 degree Celsius.

• The accepted SI unit of energy is the joule.• 1 kcal = 4.18 kilojoules (kJ)

Four Basic Forms of Energy Chemical – for synthesis of new compound Mechanical – for muscle contraction Electrical – for brain and nerve activity Thermal – for regulation of body temperature

Human are inefficient energy users because they can convert only 25% of chemical energy from the food they eat into mechanical energy (walking, typing)

Energy Needs of the Body( 3 Factors) Basal metabolism Energy for physical activity Specific dynamic action (SDA) – a small

amount of additional energy expended during digestion and absorption of carbohydrates. Proteins and fats in the gastrointestinal tract.

Basal Metabolism Is the minimum amount of energy required to maintain

vital functions in an organism at complete rest, measured by the basal metabolic rate in a fasting individual who is awake and resting in a comfortably warm environment.

Basal Metabolic Rate (BMR) – is the rate at which energy is used by an organism at complete rest, measured in humans by the heat given off per unit time, and expressed as the calories released per kilogram of body weight or per square meter of body surface per hour.

Basal Metabolic Rate Higher in young people It increases for some months after birth, then

decreases through adolescence The basal metabolism of healthy men requires about

1600 to 1800 kcal daily while for women is about 1200 to 1450 kcal.

Factors that can Increase the BMR Muscular development Body temperature Pregnancy Lactation

Physical Activity Muscular activity affects both energy expenditure and heat

production Energy expenditure increases with muscular activity Maintenance Activity: sitting most of the day, about 2 hours

of moving about slowly or standing. Light Activity: typing, teaching, shopwork, laboratory work,

some walking. Moderate Activity: walking, housework, gardening,

carpentry, cycling, tennis. Strenuous Activity: pick-and-shovel work, swimming,

basketball, running

Specific Dynamic Action of Food Is the term used to describe the expenditure of calories

during the digestion and absorption of food. Studies have shown that the heat increment, or

thermogenic response, necessary to digest and absorb fat is 2%, for carbohydrate is 6%, and for protein-rich foods is about 12%.

In general, the specific dynamic effect of diet is calculated to contribute approximately 10% of the consumed calories.

Body Composition

The Spectrum of Body Size, Shape and Composition

We All Change in Many Ways

What are the different ways to look at human body

composition?

Medical (health)

Anthropological

Performance

Appearance

Why is knowledge of body composition so important?

Health and Disease

Performance

Appearance

Longevity

What Is Body Composition? Body composition = the body’s relative amounts of fat

mass and fat-free mass (bone, water, muscle, connective and organ tissues, teeth)

Essential fat = crucial for normal body functioning 3–5% of total body weight in males 8–12% of total body weight in females

Nonessential fat = adipose tissue

Typical Body Composition

prepared by: R. Escudero

ObesityAnd its Associated Risk Factors

Definition of terms: Overweight – refers to excessive amounts of

muscle or bone and water as well as to body fat.

Obesity – concerned only with an abnormally increased amount of body fat.

ObesityAn Overview

Overweight and obesity are both chronic conditions that are the result of an energy imbalance over a period of time.

The cause of this energy imbalance can be due to a combination of several different factors and varies from one person to another.

Individual behaviors, environmental factors, and genetics all contribute to the complexity of the obesity epidemic.

Overweight and Obesity The most important consideration in evaluating body

weight and composition is the proportion of total body weight that is fat (percent body fat)

Overweight = total body weight above a recommended range for good health

Obesity = severely overweight and overfat; characterized by excessive accumulation of body fat

Overview of Various Body Composition Assessment Methods

Overview of Various Body Composition Assessment Methods (cont.)

Energy ImbalanceWhat is it?

Energy balance can be compared to a scale.

An energy imbalance arises when the number of calories consumed is not equal to the number of calories used by the body.

Weight gain usually involves the combination of consuming too many calories and not expending enough through physical activity.

Weight Gain

Calories Consumed > Calories Used

Weight Loss

Calories Consumed < Calories Used

No Weight Change

Calories Consumed = Calories Used

2009

Energy ImbalanceEffects in the Body

Excess energy is stored in fat cells, which enlarge or multiply. Enlargement of fat cells is known as hypertrophy,

whereas multiplication of fat cells is known as hyperplasia.

With time, excesses in energy storage lead to obesity.

Fat cells

J La State Med Soc .2005; 156 (1): S42-49.

Fat Cell EnlargementHypertrophy

Enlarged fat cells produce the clinical problems associated with obesity, due to the following:

The weight or mass of the extra fat The increased secretion of free fatty acids

and peptides from enlarged fat cells.

Weight ClassificationsA Review

Body mass index (BMI) is a mathematical ratio which is calculated as weight (kg)/ height squared (m2). It is used to describe an individuals relative weight for height, and is significantly correlated with total body fat content. BMI is intended for those 20 years of age and older.

With a BMI of: You are considered:

Below 18.5 Underweight

18.5 - 24.9 Healthy Weight

25.0 - 29.9 Overweight

30 or higher Obese

Mortality and MorbidityAssociated with Obesity

The effects of excess weight on mortality and morbidity have been recognized for more than 2,000 years. It was Hippocrates who recognized that “sudden death is more common in those who are naturally fat than in the lean.”

Today, obesity is increasing rapidly. Research shows that many factors related to obesity influence mortality and morbidity.

MortalityWeight, Fat Distribution, and Activity

The following factors have been shown to increase mortality in individuals:

Excess body weight Regional fat distribution Weight gain patterns Sedentary Lifestyle

MortalityExcess Body Weight

Mortality associated with excess body weight increases as the degree of obesity and overweight increases.

It is estimated that 280,000 to 325,000 deaths a year can be attributed to obesity in the United States, more than 80% of these deaths occur among individuals with a BMI greater than 30 kg/m2.

Regional fat distribution can contribute to mortality. This was first noted in the beginning of the 20th century. Obese individuals with an android (or apple) distribution of body fat are at a

greater risk for diabetes and heart disease than were those with a gynoid distribution (pear).

Android fat distribution results in higher free fatty acid levels, higher glucose and insulin levels and reduced HDL levels. It also results in higher blood pressure and inflammatory markers.

MortalityRegional Fat Distribution

Android Gynoid

In addition to overweight and central fatness, the amount of weight gain after ages 18 to 20 also predicts mortality.

The Nurses’ Health Study and the Health Professionals Follow-up Study showed that a marked increase in mortality from heart disease is associated with increasing degrees of weight gain.

MortalityWeight Gain

Sedentary lifestyle is another important component in the relationship of excess mortality to obesity.

A sedentary lifestyle increases the risk of death at all levels of BMI.

Unfit men in the BMI range of less than 25 kg/m2 had a significantly higher risk than men with a high level of cardiovascular fitness.

Obese men with a high level of fitness had risks of death that were not different from fit men with normal body fat.

MortalitySedentary Lifestyle

Morbidity Associated with Obesity

Overweight affects several diseases, although its degree of contribution varies from one disease to another.

Additionally, the risk of developing a disease often differs by ethnic group, and by gender within a given ethnic group.

Obstructive sleep apnea Osteoarthritis Cardiovascular disorders Gastrointestinal

disorders Metabolic disorders

Endometrial, prostate and breast cancers

Complications of pregnancy Menstrual irregularities Psychological disorders

Individuals who are obese are at a greater risk of developing:

Morbidity Associated with Obesity

Cardiovascular DisordersAssociated with Obesity

HypertensionStroke

Coronary Artery Disease

Obese individuals are at a greater risk of developing these cardiovascular disorders:

2009

Hypertension Hypertension (HTN) is the term for high blood pressure. Hypertension is identified when a blood pressure is

sustained at ≥140/90 mmHg. High blood pressure is referred to as the “silent killer,”

since there are usually no symptoms with HTN. Some individuals find out that they have high blood

pressure when they have trouble with their heart, brain, or kidneys.

NHLBI

HypertensionThe Dangers

The heart to get larger, which may lead to heart failure. Small bulges (aneurysms) to form in blood vessels. Blood vessels in the kidney to narrow, which may lead to kidney failure. Arteries in the body to harden faster, especially those in the

heart, brain, kidneys, and legs. This can cause a heart attack, stroke, kidney failure, or can lead to amputation of part of the extremities.

Blood vessels in the eye to burst or bleed. This may cause vision changes and can result in blindness.

Failure to find and treat HTN is serious, as untreated HTN can cause:

Hypertension

Blood pressure is often increased in overweight individuals. Estimates suggest that control of overweight would eliminate 48%

of the hypertension in Caucasians and 28% in African Americans. Overweight and hypertension interact with cardiac

function, leading to thickening of the ventricular wall and larger heart volume, and thus to a greater likelihood of cardiac failure.

Hypertension Prevalence in the Overweight

0

5

10

15

20

25

30

35

Males Females

BMI < 25BMI > 25 & < 27BMI > 27 & <30

Prev

alen

ce o

f H

TN

Age-adjusted prevalence of hypertension in

overweight U.S. adults

14.9

22.1

27.0

15.2

27.7

32.7

Stroke Normally, blood containing oxygen and

nutrients is delivered to the brain, and carbon dioxide and cellular wastes are removed.

A stroke occurs when the blood supply to part of the brain is suddenly interrupted by a blocked vessel or when a blood vessel in the brain bursts.

Once their supply of oxygen and nutrients from the blood is cut off to the brain cells, they die.

Stroke

Sudden numbness or weakness, especially on one side of the body Sudden confusion or trouble speaking or understanding speech Sudden trouble seeing in one or both eyes Sudden trouble with walking, dizziness, or loss of balance or coordination Sudden severe headache with no known cause

The symptoms of a stroke include:

Stroke There are two forms of stroke: ischemic and hemorrhagic. Ischemic stroke occurs when an artery to the brain is blocked. Overweight and obesity increase the risk for ischemic stroke in men and women. With increasing BMI, the risk of ischemic stroke increases progressively and is

doubled in those with a BMI greater than 30 kg/m2 when compared to those having a BMI of less than 25 kg/m2.

Hemorrhagic strokes occur when a blood vessel in the brain erupts. Overweight and obesity do not increase the risk for hemorrhagic strokes.

Coronary Artery Disease Coronary artery disease (CAD) is a type of atherosclerosis that occurs when the arteries

supplying blood to the heart muscle (coronary arteries) become hardened and narrowed. This hardening and narrowing is caused by plaque buildup. As the plaque increases in size, the insides of the coronary arteries get narrower, and

eventually, blood flow to the heart muscle is reduced. This is critical because blood carries much-needed oxygen to the heart.

Coronary ArteriesBlood Flow

When the heart muscle is not receiving the amount of oxygen that it needs, one of two things can happen:

Angina Heart Attack

AnginaThis is the chest pain or discomfort that occurs

when the heart is not getting enough blood.

Heart attack This is what happens when a blood clot develops

at the site of the plaque in a coronary artery. The result is a sudden blockage, which may

block all or most of the blood supply to the heart muscle. Because cells in the heart muscle begin to die when they are not receiving adequate amount of oxygen, permanent damage to the heart muscle

can occur if blood flow is not quickly restored.

2009

Coronary Artery Disease

Over time, CAD can weaken the heart muscle and contribute to:

Heart Failure Arrhythmias

Heart FailureIn this condition, the heart can’t pump blood

effectively to the rest of the body. Heart failure does not mean that the heart has

stopped nor does it mean that it is about to. It means that the heart is failing to pump

blood the way that it should.

Arrhythmias Arrhytmias are changes in the normal

beating rhythm of the heart. They can be either faster or slower than normal.

Some arrhythmias can be quite serious.

2009

Coronary Artery Disease Obesity is associated with an increased risk for CAD. Abdominal fat distribution is believed to be related as well. Data from the Nurses Health Study illustrated that women in the lowest BMI but

highest waist-to-hip circumference ratio had a greater risk of heart attack than those in the highest BMI but lowest waist-to-hip circumference ratio.

Regional fat distribution appears to have a greater effect on CAD risk than BMI alone.

Gastrointestinal DisordersAssociated with Obesity

Obese individuals are at greater risk of developing these gastrointestinal disorders:

Colon CancerGall stones

Colon Cancer Colorectal cancer is a term used to refer to cancer that

develops in the colon or the rectum.

The colon (a.k.a. the large intestine) is about 5 feet long and its role in the digestive system is to continue to absorb water and mineral nutrients from food. Once this process of absorption is complete, waste matter (feces) remains.

The rectum is the final 6 inches of the digestive system. Feces are passed from the large intestine to the rectum, to exit the body through the anus.

Colon Cancer Colorectal cancer is the second leading cause of cancer-related deaths in the U.S. It is estimated to cause about 55,170 deaths during 2006.

Colon CancerFindings Relating to Obesity

Colon cancer has been shown to occur more frequently in people who are obese than in people who are of a healthy weight.

An increased risk of colon cancer has been consistently reported for men with high BMIs.

Women with high BMI are not at increased risk of colon cancer.

There is evidence that abdominal obesity may be important in colon cancer risk.

Gallbladder Disease Cholelithiasis is the primary hepatobiliary pathology associated with overweight. Cholelithiasis is a condition characterized by the presence or formation of

gallstones in the gallbladder or bile ducts. Normally, a balance of bile salts, lecithin, and cholesterol keep gallstones from

forming. However, if there are abnormally high levels of bile salts or, more commonly, cholesterol, then stones can form.

GallstonesFindings Related to Obesity

Obesity appears to be associated with the development of gallstones. More cholesterol is produced at higher body fat levels. Approximately 20 mg of additional cholesterol is synthesized for each kg of extra

body fat. High cholesterol concentrations relative to bile acids and phospholipids in bile

increase the likelihood of precipitation of cholesterol gallstones in the gallbladder.

GallstonesFindings Related to Obesity

In the Nurses’ Health Study, when compared to those having a BMI of 24 or less, Women with a BMI > 30 kg/m2 had a 2-fold increased risk for symptomatic gallstones. Women with a BMI > 45 kg/m2 had a 7-fold increased risk for symptomatic gallstones.

The relative increased risk of symptomatic gallstone development with increasing BMI appears to be less for men than for women.

GallstonesFindings Related to Obesity Ironically, weight loss leads to an increased risk of gallstones--

because of the increased flux of cholesterol through the biliary system.

Diets with moderate levels of fat that trigger gallbladder contraction and subsequent emptying of the cholesterol content may reduce the risk of gallstone formation.

Bile acid supplementation can be used to lower ones risk for gallstone formation.

Metabolic DisordersAssociated with Obesity

Obese individuals are at greater risk of developing these metabolic disorders:

Diabetes MellitusDyslipidemiaLiver Disease

Diabetes Mellitus

Type 2 diabetes mellitus (DM) is strongly associated with overweight and obesity in both genders and in all ethnic groups.

The risk for Type 2 DM increases with the degree and duration of overweight in individuals.

The risk for Type 2 DM also increases in individuals with a more central distribution of body fat (abdominal).

Obesity and Type 2 DMIn the United States

Among people diagnosed with Type 2 diabetes, 55 percent have a BMI

≥ 30 (classified as obese), 30 percent have a BMI ≥ 25 or ≤30

(classified as overweight), and only 15 percent have a BMI ≤ 25

(classified as normal weight).

BMI < 25BMI > 25 or BMI < 30BMI > 30

15%

30%55%

Diabetes MellitusFindings Related to Obesity

The Nurses’ Health Study demonstrated the curvilinear relationship between increasing BMI and the risk of diabetes in women: Women with a BMI below 22 kg/m2 had the lowest risk of DM At a BMI of 35 kg/m2, the relative risk of DM increased 40-fold or 4,000%

The Health Professionals Follow-up Study demonstrated a similar relationship between increasing BMI and the risk of diabetes in men: Men with a BMI below 24 kg/m2 had the lowest risk of DM At a BMI of 35 kg/m2, the relative risk of DM increased 60-fold or 6,000%

Diabetes MellitusFindings Relating to Weightloss Weight loss reduces the risk of developing diabetes.

In the Health Professionals Follow-up Study, a weight loss of 5-11 kg decreased the relative risk for developing diabetes by nearly 50%.

Type 2 DM was almost nonexistent with a weight loss of more than 20 kg (44 lbs) or in those with a BMI below 20.

Dyslipidemia Dyslipidemia is defined as

abnormal concentration of lipids or lipoproteins in the blood.

As BMI increases, there is an increased risk for heart disease.

This is because a positive correlation between BMI and triglyceride (TG) levels has been demonstrated.

DyslipidemiaFindings Related to Obesity

An inverse relationship between HDL cholesterol and BMI has been noted. This relationship may be more important than the relationship between

BMI & TG levels. Low level of HDL carries more relative risk for developing heart disease

than do elevated triglyceride levels. Central fat distribution also plays an important role in lipid abnormalities. Excessive body fat in the abdominal region leads to increased circulating

triglyceride levels.

HDL

Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is the term given to describe a collection of liver abnormalities that are associated with obesity.

In a cross-sectional analysis of liver biopsies of obese patients, it was found that the prevalence of steatosis, steatohepatitis, and cirrhosis were approximately 75%, 20%, and 2% respectively.

Liver DiseaseFatty Liver

Steatosis is the term for “fatty liver” and it is not actually a disease, but rather a pathological finding.

Most cases of fatty liver are due to obesity.

Other causes of fatty liver include: Diabetes Certain drugs Intestinal bypass operations Starvation Protein malnutrition Alcoholism

Liver DiseaseFatty Liver

A gradual weight reduction can help to reduce the enlargement of the liver due to fat, and it can normalize the associated liver test abnormalities.

It is important to limit the amount of alcohol consumed in the diet. Alcohol can decrease the rate of metabolism and secretion of fat in the liver.

Importance of a Healthy Liver

The 300 billion cells of the liver control a process known as metabolism. During metabolism, the liver breaks down nutrients into usable products. These products are then delivered to the rest of the body through the bloodstream.

The liver also metabolizes toxins into byproducts that can be safely eliminated.

The liver also produces many important substances, such as: albumin, bile, cholesterol, clotting factors, globin, and immune factors.

The liver is the largest organ in the body and it plays a vital role in performing many complex functions that are essential for life:

Obstructive sleep apneaOsteoarthritis

Endometrial, prostate, and breast cancersComplications of pregnancy

Menstrual irregularitiesPsychological disorders

Other DisordersAssociated with Obesity

Obese individuals are at greater risk of developing these metabolic disorders:

Obstructive Sleep Apnea Obstructive sleep apnea is caused by repetitive upper airway obstruction during sleep

as a result of narrowing of the respiratory passages. Patients having the disorder are most often overweight with associated peripharyngeal

infiltration of fat and/or increased size of the soft palate and tongue.

Obstructive Sleep Apnea Common complaints are loud snoring, disrupted sleep,

and excessive daytime sleepiness. Individuals with sleep apnea suffer from fragmented sleep

and may develop cardiovascular abnormalities because of the repetitive cycles of snoring, airway collapse, and arousal.

Because many individuals are not aware of heavy snoring and nocturnal arousals, obstructive sleep apnea may remain undiagnosed.

Obstructive Sleep ApneaFindings Relating to Obesity

Obstructive sleep apnea affects around 4% of middle-aged adults. Individuals having a BMI of at least 30 are at greatest risk for sleep apnea. Weight loss has been shown to improve the symptoms relating to sleep apnea.

Osteoarthritis Osteoarthritis (OA) is the most common type of arthritis 40 million Americans currently have osteoarthritis. It is a degenerative disease which frequently leads to chronic pain and disability. For individuals over the age of 65, it is the most disabling disease. Currently, only the symptoms of OA can be treated; there is no cure.

Osteoarthritis Findings Relating to Obesity

The incidence of OA is significantly increased in overweight individuals.

OA that develops in the knees and ankles is probably directly related to the trauma associated with the degree of excess body weight.

Osteoarthritis in other non-weight bearing joints suggests that there must be some component of the overweight syndrome responsible for altering cartilage and bone metabolism, independent of the actual stresses of body weight on joints.

Areas of the body most commonly affected by OA

CancerFindings Relating to Obesity

Overweight and obesity are associated with an increased risk of: esophageal, gallbladder, pancreatic, cervical, breast, uterine,

renal, and prostate cancers.

Obesity and physical inactivity may account for 25 to 30 percent of several major cancers, including--- colon, breast (postmenopausal), endometrial, kidney, and cancer of the esophagus.

Endocrine Changes There are various endocrine changes associated with overweight. Changes in the reproductive system are among the most common. Irregular menses and frequent anovular cycles are common. Rates of fertility may also be reduced.

Endocrine ChangesAssociated with Obesity

Increased cortisol production Insulin resistance Decreased sex hormone-binding globulin in women Decreased progesterone levels in women Decreased testosterone levels in men Decreased growth hormone production

Common hormonal abnormalities associated with obesity

Psychological DisordersAssociations with Obesity

Obesity is associated with an impaired quality of life. Higher BMI values are associated with greater adverse effects. When compared to obese men, obese women appear to be at

a greater risk for psychological dysfunction. This may be due to the societal pressure on women to be thin.

Psychological DisordersWeight Loss

Intentional weight loss has been consistently associated with improved quality of life.

Severely obese patients who lost 43 kg through gastric bypass demonstrated improved quality of life scores to such an extent that their post-weight loss scores were equal to or even better than population norms.

In Conclusion

Diabetes mellitus Hypertension Gallbladder Disease Liver Disease Cancer Coronary Artery Disease Cerebrovascular disease (stroke) Endocrine Changes

Psychosocial Function Obstructive Sleep Apnea Osteoarthritis

The following conditions have been found to be associated with obesity:

These diseases have been found to be associated with increased metabolic

activity (secretion) of fat cells in obesity

These diseases have been found to be associated with increased fat mass