Fat Matters: Myths and Reality of Weight Loss Dr Alex. Johnstone
Obesity – not a new problem • ‘obese people and those desiring to lose weight should perform hard work before food. Meals should be taken after exertion and while still panting from fatigue. • They should, moreover, only eat once per day and take no baths and sleep on a hard bed and walk naked as long as possible’. • Hippocrates, 5th century B.C. From: Bray, Bouchard and James (1997) Handbook of Obesity.New York, Marcel Dekker, USA, pp 1-29.
Calculating your BMI Body Mass Index (BMI) is a measure in the variation in weight for persons of the same height due to fat mass BMI is the weight in kilograms divided by the square of the height in metres, for use in adults only
The Future for UK Adults “It is anticipated that by 2010 around 25% of the UK population will be obese “ The Weight of the Nation Report (1999)
Catching up with the USA… Overweight & Obesity in the US
Consequences of Obesity Health and well-being: Increased body fatness is linked to cardiovascular disease, diabetes, hypertension, osteoarthritis, some cancers and numerous social problems. Decreased life expectancy of ~9 years. Financial: It thought to cost the UK NHS an estimated £0.5billion per annum in treatment costs and up to £2billion a year impact on the economy through premature death and lost years in working life.
Relative Risk of Health Problems associated with Obesity in Developed Countries Life expectancy deaths linked to obesity DECREASE life by 9 YEARS
Consequences of Overnutrition: Financial • Diabetes costs the NHS £1 million an hour • = £9bn per year (10% of NHS budget) • 2.75 million diabetic patients in the UK • = 2 million with type 2 diabetes • Diabetes causes more deaths than breast and • prostate cancer combined
Abdominal Obesity Normal Type 2 Diabetes
Gender specific classification of Obesity Risk based on Waist Circumference Lean, ME, Han TS, Morrison CE. Waist circumference as a measure for indicating need for weight management. BMJ 1995;311(6998):158-61. Waist circumference (cm) Men: Level 1 Increased risk 94-102 Level 2 Substantially increased risk >102 Women: Level 1 Increased risk 80-88 Level 2 Substantially increased risk >88
Why can’t I lose weight ? ‘I have a slow metabolic rate’ ‘I only have to look at a cream cake to gain weight’ ‘This is my natural weight’ ‘Once I lose it, I regain it’ ‘Weight loss lowers my metabolism’ ‘Losing weight is difficult because I feel tired’ ‘Rapid weight loss is all water loss’ ‘I’m not fat – I’ve got big bones’ ‘It’s all in my genes, doctor’
Myth 1: ‘I only have to look at a cream cake to gain weight’
Examine people’s food intake Accurately recording/remembering your intake is difficult!
‘I only have to look at a cream cake to gain weight’ FALSE- No such thing as ‘small eaters’ Record your food intake in a diary, what about your physical activity level?
Myth 2: ‘I have a slow metabolic rate’
What is Metabolic Rate ? Metabolic rate is the minimum amount of energy the body requires at rest, in a thermoneutral environment, having not eaten in the past 12 hours. It is really how much the energy the brain and major organs require to keep the body going at rest.
Measure metabolic rate in the laboratory Obese subjects have a higher metabolic rate in comparison to lean subjects because they are heavier in weight. The more lean tissue (muscle) in the body, the higher the metabolic rate because lean tissue is metabolically active.
‘I have a slow metabolic rate’ FALSE- but as we age, our metabolic rate does decline, due to decreasing muscle mass. Exceptions: Illness (e.g. thyroid disease and diabetes), which will alter metabolic rate
Myth 3: ‘Weight loss lowers my metabolism’
Measure metabolism during weight loss TRUE As you reduce body weight, metabolism will be reduced.
‘Weight loss lowers my metabolism’ So, to maintain your levels, increase energy expenditure during weight loss Get on your bike!
Myth 4: ‘This is my natural weight’
‘This is my natural weight’ • Theory in 1970’s - 1980’s that we had a • pre-determined ‘set point’ in body weight • The weight at which out body ‘naturally’ • will be maintained • Dieting would be unnecessary…
The Siberian hamster, is a seasonal model of body weight regulation Winter Summer
Seasonal body weight regulation exists in some animals • The hamster uses photoperiod to adjust the level of body weight that will be defended against energy imbalance - anticipatory changes in food intake and body weight despite provision of food in excess • Energy balance systems areregulated by day-length (photoperiod) in addition to • nutritional status SummerWinter (obese) (lean)
How does this relate to man? • No evidence of one set-point control • model in man. Control of body weight • is multi-factorial. • Can the characteristics of the seasonal • mammal lead us to novel components • of the body weight regulatory system?
Myth 5: ‘Losing weight is difficult because I feel tired’
Monitor fatigue before, during and after weight loss TRUE - dieting can induce fatigue. Different diets may have variable effects?
Common weight loss strategies - which one for me? French et al. (1999) Sales of meal-replacements £80 million; diet magazines £5 million
Myth 6: ‘Rapid weight loss is all water loss, anyway’
Measure changes in body composition TRUE - rapid weight loss at the outset of dieting, is due to the mobilisation of glycogen stores e.g. Atkins diet
‘Rapid weight loss is all water loss, anyway’ Opt for a slow but steady weight loss to optimisefat mass loss
Myth 7: ‘Once I lose it, I regain it’ Before After
Most people who lose weight, regain it – why? TRUE- most dieters will regain back the lost weight Need more research on how to promote longer-term weight maintenance.
Diogenes Study: Prevention of weight regain Larsen et al. (2010) - Diets with High or Low Protein Content and Glycemic Index for Weight-Loss Maintenance New England Journal of Medicine, 363: 2102-2113. • Weight regain was 0.93kg • less for participants on a • high protein diet than for • those on a low protein diet • Fewer participants in the high-protein, low-GI groups dropped • out of the project than in the low protein, (~26% vs. ~37%)
Treatment of obesity “Don’t step on it… it makes you cry.”
Treatment of obesity • ‘Most people will not stay in treatment for • obesity. Of those who stay in treatment, • most will not lose weight, of those who do • lose weight, most will regain it.’Stunkard (1958) • ‘Our obesogenic environment makes it easy to • gain weight; weight loss is difficult. Development • of preventative dietary strategies to control • appetite and improve health will assist in achieving • weight control.’ Johnstone (2008)
Myth 8: ‘I’m not fat, I’ve gotbigbones’
Measure Bone Mineral Content (BMC) Actual BMC can be measured by performing a whole-body DEXA scan
Bone mass Soft tissue
How much bone? Adult female about 2.5kg (at 60kg = 4% total weight) Adult male about 3.5kg (at 75kg = 4% total weight) Water is the largest component of body composition
Myth 9: ‘It’s in my genes, doctor’
“It’s in my genes” - obesity is strongly heritable… but so is underweight Identical twins Non-identical twins ‘Essential’ body weight genes primarily affect energy intake
Leptin- what about human obesity? From Farooqi et al. (2002) Journal of Clinical Investigation 110: 1093-1103
Benefit still there after 4 years From O’Rahillyet al. (2003) Endocrinology 144:3757-3764
‘It’s in my genes, doctor’ • Major gene defects account for a small • proportion of obesity cause in the UK, and • tend to be in specific ethnic groups • Obesity can be ‘hereditary’ in terms of learning • eating and exercise habits at a young age • Genes can make you pre-disposed to obesity, • under the right environmental conditions • Phenotype and genotype determine risk
Protein and appetite control for weight loss • Weight loss is easy - energy intake < expenditure • Hunger is one of the main reasons why people fail to comply to a weight loss diet • How can we develop dietary strategies that fulfill hunger and still achieve weight loss ? • Macronutrient composition of the diet is important to contribute to satiety during weight loss Johnstone (2009) British Journal of Nutrition, 101, 1729-30.
The appetite system - eating as a form of behaviour • We eat because: • Hungry • Social experience • Time • Enjoyable – reward • For energy • Health • We stop eating because: • Full • Less palatable • Less reward • Leave room for tea • Weight conscious
The satiety cascade Blundell, 1999
Satiety The satiety cascade illustrates the classes of events which constitute satiety signals arising from food consumption Sensory - generated by smell, taste, temp & texture; inhibit eating in the very short term Cognitive - beliefs we hold about food may inhibit eating in the very short term Post-ingestive - includes gastric distention, emptying, release of hormones Post-absorptive - mechanisms arising from the action of glucose, fats, amino acids, after absorption across the intestine into the bloodstream