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Critical evaluation of slimming related foods / meals available in

British supermarkets

Student number: 2159134h

Submission date: August 10th 2015

Supervisor: Professor Christine Edwards

The research project is submitted in partial fulfilment of the requirements for the

degree of MSc in Human Nutrition with specialization in Public Health Nutrition

Word count:6193

Key words: Slimming foods, ready meals, Special K challenge, fruit yogurt

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This is to certify that the work reported in this dissertation is all my own work unless

otherwise stated

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Table of contents

1.Abstract ............................................................................................................................................ 4

2.Introduction ..................................................................................................................................... 5

Background.................................................................................................................................................... 5

Ready meals................................................................................................................................................... 5

Yogurts .......................................................................................................................................................... 6

Special K and weight loss, is there a link? .................................................................................................... 7

Aims .............................................................................................................................................................. 8

3. Methods ........................................................................................................................................... 8

Selection of supermarkets chains .................................................................................................................. 8

Data collections ............................................................................................................................................. 8

Nutritional data collection ............................................................................................................................. 9

Statistical analysis ....................................................................................................................................... 10

4. Results ........................................................................................................................................... 10

Ready meals................................................................................................................................................. 10

Strawberry and raspberry yogurts ................................................................................................................ 17

Special K VS Kellogg’s ............................................................................................................................... 20

5.Discussion ....................................................................................................................................... 22

Initial overview of the findings ................................................................................................................... 22

Nutritional information ................................................................................................................................ 23

Ready meals................................................................................................................................................. 23

Strawberry/raspberry yogurts ...................................................................................................................... 25

Special K challenge ..................................................................................................................................... 26

Food price .................................................................................................................................................... 27

Limitations ................................................................................................................................................... 27

Future study ................................................................................................................................................. 28

6. Conclusion..................................................................................................................................... 28

7. Acknowledgements....................................................................................................................... 28

8. References ..................................................................................................................................... 29

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Abstract

Introduction: Over 70% adults in UK and US will be overweight by 2020. Public pay more

attention to their diet and over 80% people, especially women, have concerns over their weight in

UK. Many supermarkets launch slimming version of products in order to meet the consumers’

demand.

Aims: Compare slimming- related foods/products available in 6 supermarket with their non-

slimming version (their nutrition content, portion size and price), including strawberry/raspberry

yogurts and ready meals. Kellogg’s VS special K were compared to assess Special K challenge

program proposed by Kellogg’s

Methods: Recipes and nutritional data collected from either supermarket website or manufacture

websites. Price was obtained from ‘mypsupermarket.com’. The statistics analysis was performed

either by MINITAB version 17 or Microsoft Excel.

Results: For yogurts, significant difference for protein (P<0.05), calcium (p<0.05) and calorie

(p<0.05). For ready meals, there is not significant difference in prices. Some recipes have

significant difference in certain nutrients between slimming and non-slimming version. Salt content

are high and maybe associated with obesity, but not all significant.

Conclusions: As for special K challenge, it is healthy lifestyle that responsible for potential weight

loss rather than special K products. Cornflake product is healthier and cost-effective option,

considering their lower sugar content. The calcium and protein in raspberry and strawberry yogurt

contribute to weight loss. In terms of ready meals, portion size along with energy density have an

effect on weight loss. For other nutrient, not all were statistical significant.

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Introduction

Background

Obesity is one of the fastest growing epidemic in the 21st century. The prevalence of obesity

increases across all age group. According to the data, over 1,46 billion adults globally were

overweight in 2008 and over 70% of adults in United Kingdom and United States will be

overweight by 2020 (Finucane et al., 2011). 11 million more UK adults will be obese by 2030

(Wang et al., 2011) Being overweight and obese increase the risk of developing diseases such as

type 2 diabetes, coronary heart disease (CHD) and some types of cancer. There has been over 10%

increase in number of obese or overweight (from 52.4% to 62.6%) in the past 2 decades in Scotland.

The cost of treating obesity to NHS Scotland could reach 3 billion pounds in 2030. (The Scottish

government, 2014)

Ready meals

Research from Mintel (2014) suggested that 55% of British people (equivalent to 29 million) made

their effort to lose weight in the past years. There were only 5% of women and 17% men have

claimed that they have no concern about their weight. Ready meals have been defined as pre-

prepared main courses that can be reheated in the container, without further ingredients and

requiring minimal preparation. (Remnant and Adams, 2015) In UK, consumers spent £2.6bn on

ready meals each year, which was twice as much as France as and six times more than Spain.

(Manchester University, 2014) Over 70% of UK house hold consumed ready meals. Food Standard

Agency (2003). Among those consumers, 28% use them consumer more than once a week. The

number has risen to over 40% according to more recent data (Mahon, Vowan & McCarthy, 2006).

The shift in dietary pattern to faster and convenient manner seems to be inevitable, especially in

such a fast-moving society. Hence, consumption of ready meals is likely to be responsible for the

rise in obesity (WHO, 2003; Moneiro, 2010).

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However, the nutritional content of ready meals has attracted negative publicity. A study from

Glasgow University described current ready meal from major UK supermarkets as ‘Nutritionally

chaotic’. (Celnik et al., 2012) A cross-sectional study published in the British Medical Journal has

investigated popular main meals recipes from UK cookery books and over 100 own-brand ready

meals from 3 supermarkets. Results indicated none of them were fully complied with WHO

recommendation. (Howard et al., 2012) Ready meals have more or less undergone some industrial

processing to ensure its hygiene or to enhance palatability, texture or flavor, such as preservatives,

which may lead to loss of some nutrient, such as protein (Alkerwi et al., 2015) In addition,

consumers who regularly consume ready meals usually fail to consumer enough fruits and

vegetables. (O’Donnellet; 2008; Rosenheck, 2008; Burns et al., 2002). In order to meet the need for

weight management, some companies have marketed the product clearly stated, for example ‘Now

slim food range’ and ‘slim noodles’, or implied its association with weight management, such as

Waitrose ‘Lovelife calorie controlled’, Tesco ‘healthy living’ and Iceland ‘slimming world’.

Portion size is a concept that has been used differently in different settings, including food

manufactures, regulatory agencies and consumers, hence consumer’s food intake and perceived

satiety might be influenced by portion size. (Ueland et al., 2009). It is considered one of the

environmental determinants of energy intake. Evidence emerging that portion size of foods has

increased over the past 3 decades. When it comes to energy intake control and subsequent obesity,

effort has been made to physiological and biological events occurring after ingestion of food,

however the role of behavior control has often been neglected. (Benton, 2015). Evidence suggested

that reduced portion size and energy density independently result in significant decrease in energy

intake over 2 day (P<0.0001). 10 % decreased in energy intake resulted from 25% reduction in

portion size. (Rolls, Roe and Meengs, 2006)

Yogurts

Yogurt is an important source of calcium, energy and other micronutrients. It is a large contributor

to protein intake in western world (Astrup, 2014; Bendtsen et al., 2013) Data from Framingham

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Heart Study Offspring Cohort found 3 servings per day of total dairy consumption have been

associated with 0,1 kg smaller annual weight gain (p=0.04) and less WC gain (p=0.05), compared

with those who consuming <1 serving per day. These effects have not been observed in other dairy

products. (Wang et al., 2014) Yogurt consumption has also been linked with better diet quality and

metabolic profiles in American population (Wang et al., 2013). However, a randomized controlled

trial (RCT) found that dairy and calcium-rich diet was not linked with greater weight loss than

control group, however there was an rise in plasma PYY concentration , which enhanced the

satisfaction and reduced dietary fat intake during energy restriction period (Jones et al., 2013)

Special K and weight loss, is there a link?

Breakfast cereal is one of the most common food in western diet. It is an important source of

various vitamin and minerals, such as B vitamins and Iron. (William, 2014) There is few breakfast

cereal product claiming to contribute to weight loss, except Kellogg’s special K range. They have

launched a campaign known as special K challenge, which is a ‘simple and scientifically-proven

way to help you kick-start a healthier life style’, according to their website. It has also been pointed

out that 6 pounds weight loss can be achieved in 14 days if participants consume cereal or other

special K products for breakfast and lunch, plus a regular dinner’ and ’ Drop a jeans size in 2

weeks’. (Kellogg’s, 2012). The challenge consists 5 steps. First of all, calculate the BMI to find out

if you are eligible for the challenge. The challenge is suitable for whose BMI over 25. Secondly,

replace breakfast with a 45 g serving of special K products, and then replace either lunch or dinner

with another serving. Next, to consume a third balanced meal of your choices. Then, replace the

snacks with healthier options such as fruits & vegetables. Finally, include regular exercise in daily

routine.

Controlling food choices, along with decisions of whether and amount to eat, are important to

prevent or treat weight gain and obesity. (Mela, 2001) There are a number of product that associated

or implied its effect on weight management in British supermarkets. Therefore, question may arise

as what are the benefit of slimming foods compared with non-slimming version? What makes the

difference? Do I have to pay more to achieve the effect? There is a lack of study in comparing

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slimming foods with their corresponding non-slimming version. The study is intended to provide a

general guidance to the consumer who looks for weight loss and difficult with choices between two

versions. Three types of food as example (strawberry/raspberry yogurt, ready meals and Kellogg’s

flake products)

Aims

The purposes of this study include

Comparing slimming version of ready meals on the supermarket shelf with their corresponding

non-slimming version, in terms of their nutrition content, portion size and cost.

Comparing fat free or 0% fat, low fat and standard (neither fat free nor low fat) fruit yogurt using

raspberry/strawberry yogurt as an example.

Assessment of Kellogg’s special K challenge. This will be done by comparing special K products

with corresponding Kellogg’s products, therefore justify whether it is the special K products or

the healthy lifestyle that contribute to its weight loss effect.

2. Methods

Selection of supermarkets chains

The sourcing of the products were carried out in 6 British supermarkets chains (Iceland, ASDA,

Tesco, Morrison, Sainsbury’s as well as Waitrose), because they account for over 60% of market

share in UK (Statista, 2015). The reason why the Co-op is not included in the study is because the

online shopping is not available therefore information regarding nutrition and portion size is not

accessible. The reason why Aldi and Lidl are not included is because they are headquartered in

Germany, the regulation regarding nutritional information may be slightly different.

Data collections

Information regarding overall food categories were obtained through the ‘mysupermarket.com’,

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which enable searching the stock list and availability of certain foods/products for each supermarkets,

however it does not provide any nutritional information and portion size. Information regarding

portion sizes (1 serving) and nutrition information were either obtained from supermarket website or

manufacture site. All the nutritional information in this study was based on 1 serving or 1 portion as

the manufactures states on the package, since it reflects individual level daily intake, rather than use

100g per product. For product without mentioning the portion size or per serving, they were

considered as 1 portion or serving size.

Nutritional data collection

In terms of yogurts, they are grouped into ‘fat free or 0% fat’, ‘low fat’ and ‘standard’. The raspberry

and strawberry yogurt were chosen was because they are representative flavor that appears in almost

every yogurt brand. The reason to exclude the plain yogurt was because people are unlikely to

consume plain yogurt along, instead they usually served with dried fruit & nut or breakfast cereals,

the natural set yogurts are generally used for cooking. The calorie content vary greatly.

‘Strawberry yogurt’ and ‘raspberry yogurts’ were used in the search from 6 supermarket websites.

The type of yogurt are judged by looking at the product name. The Greek style were included.

For ready meals, range names that directly associated with slimming, were searched There are 3,

‘Slimming world’, ‘love life calorie controlled’ and weightwatchers. ‘Slimming world’ is exclusive

to Iceland and ‘lovelife calorie controlled’ for Waitrose. ‘Weightwatchers’, on the other hand, appear

in different supermarkets. The recipes from 3 ranges that associated with sliming were listed. The

corresponding non-slimming versions were searched from each of the six supermarkets’ website.

There are several ranges that are implied with healthy eating, including ASDA ‘Good & counted’,

Tesco ‘healthy living’ and Morrison ‘NuMe’ etc. will be categorized into slimming range to analyses.

The description from website were skimmed through to ensure the main ingredients were not different

among products. In order to achieve statistical significance, product with 5 different packs, including

at least 2 slimming and 2 non-slimming version, were included in the study.

The variety range of products for special K were obtained from its UK official website

(http://www.specialk.co.uk/en_gb/flakes.html), because there is a slight difference in the product

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range among different countries. The corresponding products are coming from the Kellogg’s

websites. The price of the foods were obtained from the mysupermarkets.com, since it included

prices from different retailers. The highest price appears on the mysupermarket.com for this product

will be used. The purpose of this is to avoid any effect of promotions that could lead to a variation

in price per serving, although the magnitude is negligible.

Statistical analysis

Statistical analysis are performed in Minitab (version 17). In terms of the statistical methods, the

dataset needs to be tested for its normality first, then types of statistic tests was applied depending on

its normality and groups of datasets. The methods include in this study can be MannWitney test,

Kruskal Waillis test or standard student t-tests. The justification of the statistical method applied

will be provided under ‘Result’ section in each case. The other statistical calculation was performed

by Microsoft excel 2013.

Results

Ready meals

Overall 27 recipes and 207 packs of ready meals were identified. The whole list will be found in

separate document. In order to achieve statistical significance, a recipe appear at least 5 times with

at least 2 slimming version and 2 non-slimming version were included in the analysis. Therefore 10

recipes and 129 packs were examined after selection and ingredient list check, including Chicken

tikka masala with rice, chicken curry with rice, chicken hotpot, beef hotpot, beef lasagne, spaghetti

bolognese, sweet sour chicken with rice, chicken curry, spaghetti & meatballs, tomato & basil pasta.

The whole list will be found in the separate document.

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Figure 1: Comparison of calorie contents between slimming-version and non-slimming version of 10 ready meals; * p<0.05; ** p<0.01

Figure 1 shows the comparisons of calorie contents of 10 ready meals recipes. The white bar

represent for the slimming version, whereas grey bars are non-slimming version. Mann-Whitney

test were performed, since the data was not normally distributed and 2 items in each group. The

result indicate that a significant difference of calorie contents in 4 out 10 recipes, chicken tikka

masala (p<0.01), Chicken curry with rice (p<0.05), beef lasagna (p<0.05) as well as green Thai

curry with rice (p<0.05).

Figure 2: Comparison of carbohydrate contents between slimming-version and non-slimming version of 10 ready meals Note: * p<0.05;** p<0.01; X

value that over or below the limit range

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Figure 2 shows the difference in carbohydrate contents of slimming version and non-slimming

version of the 10 ready meals. The white bar represent for the slimming version, whereas blue bars

are non-slimming version. The Mann-Whitney test was performed, because data was not normally

distributed. In several recipes, the slimming version had less carbohydrate statistically significant in

Chicken tikka masala with rice (p<0.01), chicken curry with rice (p<0.05).

Figure 3: Comparison of sugar contents between slimming-version and non-slimming version of 10 ready meals Note: * p<0.05;** p<0.01; X: value

below or above the limit range

Figure 3 shows the difference in sugar content of examine ready meals. In general, there was no

difference in the sugar content between slimming and non-slimming version. Only 2 out 10 meals

are statistically significant, Chicken tikka masala with rice (p<0.01) and sweet & sour chicken with

rice (p<0.05). Sainsbury’s spaghetti Bolognese (430g) had higher sugar content in the non-

slimming version.

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Figure 4: Comparison of fat contents between slimming-version and non-slimming version of 10 ready meals Note: * p<0.05;** p<0.01

Figure 4 shows the differences in fat content of the ready meals examined. Generally, the non-

slimming version of ready meals had higher fat content than the corresponding slimming version,

but only three out 10 recipes had significantly more fat in the standard version- chicken tikka

masala with rice (p<0.01), chicken curry with rice (p<0.05), Beef lasagne (p<0.05) and Green Thai

Chicken Curry (p<0.05)

Figure 5: Comparison of saturated fat contents between slimming-version and non-slimming version of 10 ready meals Note: * p<0.05;** p<0.01; X

value below or above the limit range

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In terms of saturated fat, -chicken tikka masala with rice (p<0.01), chicken hotpot (p<0.05), beef

lasagne (p<0.01) and spaghetti and meatballs (p<0.05) had higher saturated fat content in the

standard, compared with slimming versions Tesco big night in chicken tikka masala with rice from

had extremely high saturated content.

Figure 6: Comparison of fiber contents between slimming-version and non-slimming version of 10 ready meals Note: * p<0.05; X value that beyond

the limit range

It may be thought that slimming versions of meals would contain more fibre to reduce the energy

density of the ready meals. Figure 6 shows the comparisons of fiber contents between slimming-

version and non-slimming version of 10 ready meals. There was no difference in fiber content,

except for in sweet and sour chicken with rice (p<0.05) where there was more fiber in the non-

slimming versions.

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Figure 7: Comparison of protein contents between slimming-version and non-slimming version of 10 ready meals Note: * p<0.05;

When comparison was made of protein contents between slimming-version and non-slimming

version of 10 ready meals, Two out of 10 were statistically significant- chicken tikka masala with

rice (p<0.01) and chicken hotpot (p<0.05). Green Thai chicken curry with rice has higher protein in

the non-slimming versions

Figure 8: Comparison of salt contents between slimming-version and non-slimming version of 10 ready meals Note: * p<0.05; X value below or

above the limit range

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Figure 8 shows the comparison of salt contents between slimming version and non-slimming

version of 10 ready meals. Two out of 10 recipes have significant difference in salt content-

Chicken tikka masala with rice (p<0.05) and beef lasagne (p<0.05). Iceland meal for one minced

beef hotpot have 3.4g salt for one serving, which is half of daily allowance. This is due to the large

portion size (500g).

Figure 9: Comparison of portion sizes between slimming-version and non-slimming version of 10 ready meals Note: * p<0.05;

Figure 9 shows the comparisons of portion size between slimming-version and non-slimming

version of 10 ready meals. There was no difference in portion size, except for chicken tikka masala

with rice (p<0.05) and beef hotpot (p<0.05)

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Figure 10: Comparison of prices between slimming-version and non-slimming version of 10 ready meals

Figure 10 shows the comparisons of price between slimming-version and non-slimming version of

10 ready meals. There was no significant difference between 2 groups. Slimming versions of Green

Thai chicken curry with rice and Tomato thai basil pasta are clearly cheaper than non-slimming

version

Strawberry and raspberry yogurts

Overall 76 strawberry and raspberry yogurts, including 21 fat free, 19 low fat and 36 standard non-

slim version were included in this study. The list of items will be found in the separated folder. The

reason plain yogurts were not studied is because public are unlikely to consume the plain yogurt

alone, instead they tend to consumer along with cereals and other foods, the calorie content of

which vary substantially. For fruit yogurts, strawberry or raspberry flavor appears most frequently

across all the brands, therefore used for analysis.

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Figure 11: Comparison of fat, saturated fat and fiber contents among fat free, low fat and normal raspberry/ strawberry yogurts

Note: * p<0.05; ** p<0.01 among three groups; X value that beyond the limit range

Figure 11 shows the comparison of fat, saturated fat, salt and fibre content of 3 groups of yogurt.

Kruskal Wallis were performed because there are 3 groups of data and not normally distributed.

Results indicate that there is a statistical significance in fat content in fat free VS normal and low fat

VS normal, both (p<0.05). Similar association were found for saturated fatty acid, fat free VS

normal (p<0.05) and low fat VS normal (p<0.05). There is a great variation in fat content for

standard yogurt. Some far free yogurts have higher fiber content than normal range, for example

Shape 0% fat strawberry yogurt 4*120g, Lancashire farm fat free bio strawberry yogurt 450g

(150g) and Morrison NuMe Fat free strawberry yogurt, one from low fat group (Stapleton Farm

Low Fat Raspberry Yogurt 150g)

Figure 12: Comparison of calorie, carbohydrates, sugar and protein contents among fat free, low fat and normal raspberry/ strawberry yogurts Note: X value

that beyond the limit range; * significant compared with normal p<0.05; ** p<0.05 among three groups; Fat free, low fat, normal (left to right)

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Figure 12 shows the comparison of calorie, carbohydrate, sugar and protein content of 3 groups.

There is a clear increasing trend for the calorie content (fat free VS low fat VS normal), whereas a

decreasing trend were observed from the protein groups in the same order. They are all statistically

significant among 3 groups across the 4 nutrients (p<0.05). There is significant difference between

low fat calorie and normal calorie, fat free calorie and normal calorie. There is significant difference

in fat free carbohydrate and standard carbohydrate (p<0.05), fat free sugar and standard sugar

(p<0.05), low fat protein and standard protein (p<0.05), low fat protein and standard protein

(p<0.05). There are two products from Arla have higher protein content, because these products are

designed for exercise recovery, protein is essential in terms of repairing tissues and muscles.

Figure 13: Comparison of calcium content among fat free, low fat and normal raspberry/ strawberry yogurts Note: X stands for value that beyond the limit

range; * significant compared with normal p<0.05; ** p<0.05 among three groups

Figure 13 shows difference in calcium content across 3 groups. According to result from Kruskal

wallis test, there is significant difference among 3 groups (p<0.05).Mann-Whitney test suggest both

fat free and low fat have significant difference comparing with standard one (p<0.05). Calin +

strawberry yogurt have an almost double the calcium content (400g per serving) compared with the

rest of group. This is consistent with nutritional claim on front of pack- ‘Yogurt enriched with

vitamin D and calcium, for strong bones’.

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Special K VS Kellogg’s

Figure 14: Comparison of nutrients among special K, Kellogg's bran flakes and cornflakes (per serving)

Figure 14 shows the comparison of nutrients per serving among special K original, Kellogg’s bran

flakes and Kellogg’s cornflakes. The result suggested Kellogg’s bran flakes have highest sugar,

fiber and protein contents. Kellogg’s cornflakes has higher carbohydrate and salt for 1 serving.

For saturated content, there is not much difference among three groups.

Figure 15: Comparison of nutrients among special K with added ingredients, original and Kellogg's cornflakes (per serving)

0.5 0.1

24.0

5.1

1.42.7

0.30.6 0.2

20

64.5

3.3

0.30.3 0.1

25

2.40.9

2.10.38

0

5

10

15

20

25

30

Fat Saturated fat Carbohydrates Sugars Fibre Protein Salt

Comparison of nutrients among special K, Kellogg's bran flakes and

cornflakes (per serving)

Special K Original Kellogg's bran flakes Kellogg’s corn flakes

Gram

1 0.3

24.4

6.5

1.42.6

0.30.5 0.1

24

5.1

1.42.7

0.30.3 0.1

25

2.40.9

2.10.38

0

5

10

15

20

25

30

Fat Saturated fat Carbohydrates Sugars Fibre Protein Salt

Comparison of nutrients of among special K with added ingredients,

special K original and Kellogg's cornfleks (per serving)

Special K with added ingredients Special K original Kellogg's cornflakes

Gram

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Figure 15 shows the comparison of nutrients per serving among special K original, special K with

added ingredients and Kellogg’s cornflakes. The result suggested special K with added ingredients

has double amount of fat, saturated fat and sugars than Kellogg’s cornflakes, all of which are linked

with obesity and cardiovascular disease, whereas Kellogg’s cornflakes product has highest amount

of carbohydrate and salt. In addition, special K products have slightly higher protein and fiber

content.

Figure 16: Calories of special K original, special K with added ingredients, Kellogg's bran flakes and Kellogg's cornflakes (per serving).

Figure 16 shows the comparison of calorie content across 4 ranges of product per serving. The

result show special K with added ingredients has highest calorie content for one serving, whereas

Kellogg’s bran flakes has lowest. The special K original has same calorie content per serving with

Kellogg’s corn flakes.

119.5

113 113

107

100

102

104

106

108

110

112

114

116

118

120

122

Special K with added

ingredients

Special K Original Kellogg’s corn flakes Kellogg’s bran flakes

Calories of special K original, special K with added ingredients, Kellogg's

bran flakes and Kellogg's cornflakes (per serving)

Kcal

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Figure 17: Cost of special K original, special K with added ingredients, Kellogg's bran flakes and Kellogg's cornflakes (per serving)

Figure 17 shows the cost per serving for 4 ranges. Special K with added ingredients have the

highest cost for 1 serving, whereas Kellogg’s cornflakes product have lowest. Overall special K

products are more expensive for 1 serving compared with standard Kellogg’s cornflakes and bran

flakes.

Discussion

Initial overview of the findings

For ready meals, the present study tested difference in calorie, saturated fat, fat, carbohydrate,

sugar, salt, protein, fiber, cost and portion size between slimming and non-slimming version. For

yogurt, the study tested difference in calorie, saturated fat, fat, carbohydrate, sugar, salt, protein,

fiber, as well as calcium content among low fat, fat free or 0% fat and standard strawberry/raspberry

yogurt. In terms of breakfast cereals, study tested difference in calorie, saturated fat, fat,

carbohydrate, sugar, salt, protein, fiber, and cost across 4 ranges of products, special K with added

ingredient, special K original, Kellogg’s bran flakes and Kellogg’s corn flakes. All the data analysis

were based on 1 serving on the product. This section will give an explanation of result and

implication in nutrition science.

0.20

0.12

0.08

0.30

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

Special K Original Kellogg's bran flakes Kellogg’s corn flakes Special K with added

ingredients

Cost of special K original, special K with added ingredients,

Kellogg's bran flakes and Kellogg's cornflakes (per serving)Pounds

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Nutritional information

All the nutritional data in the study were obtained either from supermarket websites or

manufacturer’s websites, hence it is likely that difference between information provided and actual

products. The UK law allows 20% from the values variation in food packaging, to allow for

fluctuation in manufacturing process. (Cantelo et al., 2010)

Ready meals

Overall, slimming version of ready meals consistently provided lower calorie content, however not

all comparisons of slimming VS standard version were significantly different. This could be

explained by small sample size or possibly by wider range of values of meals with variation among

ingredients.

Protein is a macronutrient that may be play an important role in weight management, as protein is

associated with satiety (Westerterp-Plantenga et al., 2012), however there was no significant

difference between slimming and non-slimming version except for Chicken Tikka Masala with rice

and Chicken Hotpot (p<0.05). Sainsbury ‘taste the difference spaghetti Bolognese’, one pack

contained over 60g of protein compared with average, which was 28.1g per serving. This could due

to relative large portion size (400g) and specific ingredients, containing minced beef, cheese, milk

and all of them are protein rich food.

Fibre may play an important part for the slimming version of ready meals. Evidence suggested that

fibre could dilute energy content from energy-dense foods that contribute to obesity, therefore

energy intake reduced. (Smith and Tucker, 2011). In present study, only one out 10 recipes is

significant different in fibre content in present study. The result may be explained by small sample

size, but also different staples of the ready meals. Recent study suggested consumption of pilau rice

along with fat and protein containing curries as a part of a mixed meal have significantly lower GI

value than consume the pilau rice alone (George, Garcia and Edwards, 2015) The mechanisms of

low GI food to weight control may be explained by either enhance satiety, therefore reduced energy

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intake or increase the rate of carbohydrate metabolism, subsequently fat oxidation. (Brand-Millet et

al., 2002)

High salt content is another health issue that needs to be emphasized, even though there is limited

evidence suggesting its association with human. He et al., (2008) consumption of sugar-sweetened

soft drink result from high salt intake leads to obesity, even after adjusting cofounding (P<0.001).

Recent cohort study have confirmed the previous finding, high sodium intake has also been linked

with increased caloric intake, food consumption and worse eating habits after adjusting cofounding.

The biological mechanism salt and obesity in human is still unknown, however study in rats

suggested Slimming versions of ready meals have lower salt content, however only two out of 10

recipes were significantly different from the standard meal. The wider range of salt content may be

because of the manufacture process. Data from NHS suggest the average UK adults salt intake is

about 8.1g per day (NHS, 2015), which is higher than daily allowance intake 6g per day. In the

present study, slimming version of ready meals have generally less salt. The average salt content for

slimming version was around 1.5g per serving compared with 2 g for non-slimming version.

Moreover, it is food industry that should take responsibility to reformulate recipes in order to

provide ‘healthier’ choices.

One way that slimming meals could have lower calories is by having a smaller portion size. This may

affect intake and hunger levels. Diliberti et al., (2004) conducted a study in 180 adult customers to

compare the effects standard portion (248g) and large portion (377g) on energy intake. Portion size

had a significantly effect on intake of the meal (p<0.0001). Larger portion size was associated with

over 20% of meal intake. In our study, there is a significant difference in portion size of slimming

version and non-slimming version of ready meals. Generally, slimming versions possess smaller

portion size than non-slimming version, however owing to the smaller sample size in each group,

only 2 out of 10 were significant. Therefore, manufacture could shrink the portion size in order to

reduce total energy intake.

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Energy density is defined as the amount of energy (or calorie) per gram of food (British Nutrition

Foundation, 2015), however in our study, we focus on 1 serving size or portion, which reflect status

of intake. The addition of water to the meal content may dilute the energy density, whereas fat or

sugar content will increase the energy density. The present study showed a difference in calorie

content, with slimming versions have lower calorie per serving compared with non-slimming

version, but not all of them were significant. This could be explained small sample size. Stubbs et

al., (2004) performed a study in 6 men. The study consists of 3 phases with 14 each days. The

subject were given diet with varying energy density (0.9 kcal/g, 1.3 or 1.8 kcal/g) with

macronutrient composition held constant. The result indicated that rising energy intake is

accompanied by the increase in energy density (2419 kcal, 3059 and 3865 kcal). Bell et al., (1998)

found energy density have an impact on total energy intake independent of macronutrient intake or

palatability without hunger or fullness.

Strawberry/raspberry yogurts

Fat free or 0% fat on the label of yogurts does not necessary mean there is virtually no fat at all.

According to European Union (2015), foods claimed to be fat-free should contain no more than 0.5

g of fat per 100g or 100 ml of the product. Solid products with no more than 3 g of fat per 100g or1.5

g per 100 ml for liquids can be claimed as ‘low fat’. Clear significant difference in fat content among

three groups were observed, with standard version have highest fat content, however evidence has

linked high dairy fat intake to less central obesity. Cohort study involving 1782 middle-aged men (40

to 60 years) with 12 years follow-up, they found an inverse association between intake of dairy fat

and lower risk of central obesity after adjusting cofounding factors.(Holmberg and thelin, 2013)

Yogurt is main source of calcium that has been linked with weight management. In the present study,

significant difference in calcium content among fat free, low fat and standard version were observed ;

with fat free yogurts have higher average calcium content whereas standard yogurts have lower

content, but not all products display calcium content, therefore analysis was based on information

available. Earlier RCT found increase dietary calcium significantly accelerate the weight and fat loss

in 32 obese adults. (Zemel et al., 2004) More recent Korean National Health and Nutrition

26

Examination Surveys (KNHANES) 2007-2009 suggested calcium in dairy products may be

contribute to its weight loss, which could be explained by increase fecal fat loss and rate of fat

oxidation after calcium/dairy supplementation. Lee et al., (2014) On the other hand, it favors reducing

energy intake and facilitating the appetite control. (Tremblay and Gilbert, 2011) Moreover, deficiency

in dietary calcium intake has been associated with an increased risk of overweight or obese, according

to a cross-sectional study with 6 year follow-up. Chapur et al., (2009)

Beside calcium and fatty acid, yogurts are also source of protein. Data from out study showed a

significant difference in protein content, with fat free yogurt have higher concentration. The

association between fat free and potential effect on slimming may be explained by increased diet of

thermogenesis and therefore increased energy expenditure (Murphy et al., 2013). Another potential

mechanism can be dairy protein enhance satiety by hormone secretion. Weigle et al., (2005) found

15% increase in energy from dietary protein leads to a sustained decreased in caloric intake with

constant carbohydrate intake. This effect is mediated by leptin sensitivity and therefore significant

weight loss (p<0.05). In present study, we found a significant higher protein in fat free and low fat

yogurt compared with standard. Therefore it is likely that protein contribute to its slimming function.

Fat free yogurt should be recommended, considering its high calcium content may be contribute to

help weight loss.

Special K challenge

In order to be eligible for the Special K challenge, participants needs to be BMI over 25. However,

evidences suggest that BMI is not an accurate approach to measure the obesity. Cross-sectional study

has tested the validity of BMI-based prediction equation and impedance-based prediction equation

for body fat percentage in 5 European countries. They found classification of obesity were incorrectly

performed in 8% of all men and 7% of all women by using standard BMI method (Deurenberg et al.,

2001)

Sugar is one of the determinant of obesity. In a systematic review and meta-analysis, author concluded

that among free living subjects with ad libitum diets, intake of free sugar is a leading cause of weight

gain. Bran products have highest sugar content compare with the rest 3 groups, However special K

27

products have almost double the sugar content compared with Kellogg’s cornflakes, (average 6.5

g/serving VS 2.4 g/serving Kellogg’s corn flakes). Bran flakes have even higher sugar content

(6g/serving) compared with special K, but it has almost 3 times more fiber content (4.5g/serving VS

1.4g/ serving). Intake of fiber and wholegrain have been associated with reduced risk of obesity,

overweight and waist –to-hip ratio and effect of fiber and effect of fiber on satiety and appetite have

been proposed as major mechanism. (Smith and Tucker, 2011)

Food price

Price is another factor that affect food choices and therefore weight outcome. Andreyeva et al., (2010)

found rise in food price could make consumers switch their choice to processed, calorie-dense foods.

In the present study, comparison between special K and Kellogg’s product, it is clear that Kellogg’s

corn flakes are ‘healthier’ choice compared with bran flakes and special K, due to its lower sugar

content, however, there is no significant difference between slimming and non-slimming version of

ready meals. From the finance perspective, slimming version of ready meals should be recommended,

because of its lower energy density and smaller portion size. From government point of view, Powell

and Chaloupk (2009) pricing intervention could have a measurable effect on Americans’ weight

outcome, but unlikely to achieve significant change in obesity.

Limitations of the study

To the best of our knowledge, this is the first study that critically evaluates the slimming products

with their non-slim version, however there are still some limitations. Firstly, due to the limited time

span, the search may not be comprehensive. Secondly, product will be launched regularly which study

cannot be included. Thirdly, narrow range of foods were investigated therefore result may not be

generalized into a larger context. Finally, all the data were based on the supermarkets or

manufacturing website, there is a likelihood the variation in terms of information provided or

displayed, especially for products made nutrition claims, it is difficult to justify if the contents comply

with the claim without experiments.

28

Future study

Future study can perform a focus group that investigate consumer’s perception to the slimming

version of the food. Next, intervention study can be performed in free living subjects. Then, in

terms of ready meals, wider range of products needs to be examined, maybe group them into

different cuisines to investigate if cuisine type would have an impact on the final outcome.

Conclusion

In light of these analysis, ready meals are still considered as ‘nutritional imbalance’, due to its high

salt and fat content, although slimming versions may have better nutrition profile. Smaller portion

size is recommended to reduce total energy intake. As for special K challenge, it is healthy lifestyle

that responsible for potential weight loss rather than special K products. Cornflake products are

better choices when it comes to weight loss compared with special K products and bran flake

products, all of which have higher sugar content. Fat free yogurts, especially fortified with calcium

and vitamin D, are recommended for the slimming purpose.

Acknowledgements

I would like to thanks my parents for their financial and psychological support throughout the year.

I would like to take this opportunity to give my great appreciation to my supervisor, Professor

Christine Edwards, for her guidance and support throughout the dissertation. Also, I would like to

give my appreciation to Dr. Ada Garcia for her support during the research proposal period and

whole specialization period.

29

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