Do you think calorie controlled diets work?
Do you think all calories are the same?
Do you think people are overweight because they eat too much?
Then think again. Here are the notes from this month’s talk.
CALORIES- and why you should not count them
Everybody has heard of calories. An intake of calories which exceeds the calories expended is the commonly accepted reason for putting on weight, and to a certain extent that is true as energy not used is stored as fat. On this basis, apart from being more active, if you want to lose weight the message is to cut calories e.g.
- Current drive to restrict children to “100 calorie” snacks only
- Calorie labelling of supermarket foods
- Daily recommended calorie intake for adults of 2000 for women and 2500 for men
- NHS weight loss plan to restrict daily calories to 1400 for women and 1900 for men
- Diet groups which allow “sins” (cake, desserts etc) as part of a calorie controlled plan
- 10,000 steps/day
But it’s not as simple as that.
What is a calorie?
A calorie is a unit of energy. Two categories:
- Small calorie (gram calorie) = the amount of energy needed to raise the temperature of 1 gram of water by 1 degree Celsius at a pressure of 1 atmosphere
- Large calorie (kilogram calorie, kcal, Calorie, food calorie) = 1000 small calories
The term “calories” in this talk refers to large calories and I’ll use a capital “C”, typos apart.
So, for example, a large banana contains about 100 kcals or 100 Calories.
How do we measure food Calories?
- Bomb calorimeter – burn food and measure the temperature change in the surrounding water. Rarely used now.
- Add up the energy content of the macronutrients (fat, carbohydrate, protein) in the food and subtract the fibre (not digested)
1 g fat = 9 Calories
1g protein = 4 Calories
1g carbohydrate = 4 Calories
Calories in/Calories out (the energy balance equation)
Calories in (food) minus Calories out (energy expenditure) = weight gained/(lost)
This equation is based on the First Law of Thermodynamics, which says that energy is conserved within a system and cannot be lost. In this case, the system is us.
If the energy balance equation is positive, we gain weight.
If the energy balance equation is negative, we lose weight.
If you eat food of any type from any source, if you don’t burn it off by generating heat or exercising or any other form of energy expenditure, you will gain weight. This is true.
So, according to the energy balance equation, failure to maintain a normal weight implies one of two things;
- excess Calories in (gluttony) or
- inadequate Calories out (sloth).
Obesity is due to eating more than the body needs.
Eating less and moving more is the answer to staying lean.
That is the energy balance equation. It is generally accepted as true and incontrovertible.
This is bad news for the 66% of the population who are either overweight or obese, because the energy balance equation also implies that:
Obesity is a behavioural disorder
The blame is on the individual.
Food companies are complicit in this blame – “Calories from sugary food/drink are fine as part of a Calorie controlled diet”
Governments blame obesity on lifestyle – Michelle Obama’s “Eat less, move more” campaign, the NHS weight loss plan based on Calorie restriction etc.
The acceptance of the Calories in/Calories out hypothesis of weight control puts the blame squarely on the individual for poor food and lifestyle choices. Is this so? What does the evidence about the energy balance equation tell us?
Evidence against Calories in/Calories out
1900s – Pima Indians – lean, sinewy, fit hunter-gatherer population until white man took over their territories and fed them meagre government rations of white flour/sugar/canned goods. They got fat, 40% obesity rate, despite being very poor, on the verge of famine and labouring hard
1930s – Hilde Bruch, a German paediatrician who moved to New York in the 1930s, was shocked by the fat American children, two decades before fast food. These children ate excessively, despite medical advice and parental control. She commented: “Many made strenuous efforts to lose weight, practically giving up on living to achieve it.” But maintaining a lower weight involved “living on a continuous semi-starvation diet” and they couldn’t do it. Bruch said of obesity:
“More than in any other illness, the physician is called upon to do a special trick, to make the patient do something – stop eating – after it has already been proved that he cannot do it”
1951 – Italy and Greece – less food per capita than any other European country, 2400 Cals/d compared to 3800 Cals/d in USA. Yet the working classes, especially the women, were fat.
1961 – Trinidad – 1/3rd of women over 25 were obese with an average Calorie intake below 2000/day.
1974 – Chilean slum dwellers, very poor, mostly heavy labourers, of those over 45, 40% of men and 50% of women were obese
2005 – Sao Paulo, Brazil, slum dwellers, women were obese with thin, underweight, stunted children. Did these women really over eat whilst their children were half starved? They were too poor to overeat and too active in hard jobs to exercise more! Surely the “eat less, move more” mantra did not explain the cause of these women’s obesity?
Women’s Health Initiative
A study by the American National Institute of Health in the 1990s.
20,000 women, of which half were obese, were put on a low fat diet, eating 360 Calories/day less than their normal diet. After 8 years, their abdominal fat and waist circumference had increased and they lost on average 2lbs each. If Calories in had reduced by 360/day and 1lb fat = 3500 Calories, they should have lost 36lbs in the first year alone.
New York hospital study
100 obese people were put on a diet of between 800 and 1500 Calories/day for 2 years.
Initially, only twelve lost 20lbs and one lost 40lbs. Only two of the 100 maintained any weight loss at all after 2 years.
Tuft’s Review – an analysis of all diet trials since 1980
Weight loss of 9-10lbs in the first 6 months was followed by all weight being regained.
Pennington biomedical research centre study, USA, the largest obesity institute in the states
800 overweight/obese by an average of 50lbs each at the start, randomly assigned to 4 diets, all under eating by 750 calories/day. They lost 9lbs on average initially but were on average heavier than at the start of the trial by 1 year.
- What about exercise and the energy balance equation?
1970s – Stanford University –did a study on 13000 runners. Those with the highest mileage were leaner. But ALL got fatter every year, even those running >40m/week.
Using the energy balance equation, men in their 20s running 20m/week needed to increase their mileage to 60m/week in their 40s to stay lean, while women running 15m/week in their 20s needed to up their mileage to 75m/week by their 40s!
So exercise did not prevent weight gain in these runners.
“Exercise – the miracle cure” report from the Academy of Medical Royal Colleges Feb 2015
30 minutes of moderate exercise, 5 times a week is described as a “miracle cure”, more powerful than drugs for chronic disease, reducing the risk of CV disease, type 2 diabetes, dementia and some cancers by at least 30%. BUT exercise does not promote weight loss.
“It is time to bust the myth of inactivity and obesity – you cannot outrun a bad diet” by Malhotra, Noakes and Finney in the British Journal of Sports Medicine 2015.
This study comments:
- exercise levels have changed little over the last 30 years whilst obesity levels have rocketed
- up to 40% of those with a normal BMI have metabolic abnormalities associated with obesity (eg high BP, dyslipidaemia, non-alcoholic fatty liver disease, cardiovascular disease)
- for every 150 excess Calories of sugar (eg from Coke) the increase in prevalence of type 2 diabetes is 11 times greater than that for an identical 150 Calories from fat or protein, independent of their weight or exercise levels
- dietary carbohydrate restriction is the single most effective intervention for reducing all features of metabolic syndrome and should be the first approach in diabetes management
- a high fat/low carbohydrate diet induces high rates of fat oxidisation during exercise and is sufficient for most levels of exercise intensity without the need for added carbohydrate.
- fat is the ideal fuel for most exercise (Atlantic rowers 2018– lived on a dehydrated meal plus lots of coconut oil)
- the “health halo” of legitimising sugary food and drink by associating them with sport is misleading and increases profit at the cost of population health
- that weight can be controlled by Calorie counting and that obesity is due to lack of exercise is a false perception and the public health message should instead be on healthy food choices
Calories in/ Calories out -Conclusion
Increasing calories out by exercise alone does not control weight gain
Restricting calories in fails to achieve long term weight loss.
To quote Hilde Bruch:
“Under eating is not a cure for obesity, just a temporary reduction of a symptom. So if under eating is not a cure, over eating is not the cause”.
The 20 calories/day calculation
Let’s use the energy balance equation to calculate how much we are over eating to gain the 2lbs/year which, on average, we put on (50lbs between ages 25 and 50).
1lb fat = 3500 Calories
So 2lbs fat/year = 7000 Calories
Over 365 days, that’s 7000/365 = 20 Calories/day, roughly
20 Calories/day is equivalent to one bite of a croissant, 3 bites of an apple or 2oz beer i.e. not much!
If we really only over ate by this much, surely cutting down by two bites of a croissant a day when we started to see ourselves getting fat and lose a bit of weight would be easy? So why do we all get fatter with age?
It’s ridiculous to assume that our homeostatic mechanisms cannot cope with a variation in our Calorie intake of less than 1/100th of the daily total OR that when we start to put on weight, a tiny adjustment to our intake isn’t enough to reverse it.
The energy balance equation is true in retrospect – if you eat more then you expend you will gain weight. But this is not an explanation. It’s equivalent to explaining why someone is an alcoholic by saying it’s because they drink too much. So the evidence from observation and research studies shows that restricting Calories in and/or increasing Calories out both fail to prevent weight gain.
Why does calories in/calories out fail to explain our weight gain/loss?
The energy balance equation makes assumptions that we need to question:
- Calories in and Calories out are independent variables
- a Calorie is a Calorie
- Dependent and independent variables
The energy balance equation presumes that Calories in and Calories out are independent variables i.e if you alter one, the other is unaffected.
But they are not independent, they depend upon each other. Reduce Calories in and your body will save energy so Calories out falls, and vice versa.
Your main daily energy expenditure is your Basal Metabolic Rate (BMR).
Decreased Caloric intake can reduce BMR by 40%.
Increased Caloric intake can increase BMR by 50%.
Thus weight loss is quick at first on a Calorie controlled diet, then it slows as Calories out fall in response to perceived semi-starvation and the body expends less energy to compensate.
Your body temperature falls, you feel cold, your skin, nail and hair cells multiply more slowly so your skin and hair look dull and lifeless, you are lethargic as your muscle cells are short of energy, your concentration is poor as your brain is short of fuel and you are miserable. Calories out fall because Calories in has fallen. They are dependent variables – alter one and you alter the other. Weight loss slows or stops. Then as you lose the willpower to stay hungry/tired/miserable and go back to eating normally, the weight piles back on faster than ever because your energy expenditure is still spuriously low. This is also known as “yo-yo” dieting.
Calories out is altered by Calories in.
- A Calorie is a Calorie – right?
Here’s a quote from the British cycling website article on weight loss this week
“Weight loss is as simple as Calories in versus Calories out…It doesn’t matter what form, fat, carbs or protein, those Calories take, if the balance is negative, you will lose weight.”
This is true.
So it follows that it doesn’t matter whether the Calories in are from fat, carbohydrates or protein, all Calories are the same aren’t they? Wrong.
Here’s a quote from the US Secretary of State for Agriculture on the release of the 2011 US dietary guidelines:
“If folks want to maintain a healthy weight, they have to be sensitive to the Calories in and the Calories out – not every Calorie is the same”
In other words, whether you take those Calories in as fat, carbohydrate or protein matters a lot – their metabolism is quite different.
Carbohydrates (flour/sugar/sweets/soft drinks/beer etc) all raise blood glucose rapidly, thus stimulating the release of insulin, which drives fat into the fat cells for storage and reduces the uptake of glucose and fat by the muscles and other cells. Energy expenditure falls. Energy balance is positive. We get fat.
“Carbohydrates drive insulin drives fat storage” (Professor George Cahill from Harvard Medical School).
Fat and protein have a much lesser effect on blood glucose and hence on insulin production. Our muscle and other organ cells have more energy available to them because the fat cells take less in a lower insulin environment. Our energy expenditure rises. Energy balance is negative. We lose weight.
So the type of macronutrients (fat/carbohydrate/protein) we eat as “Calories in” alters our metabolism by altering insulin production and fat storage. Calories in alters Calories out.
- Thermic Effect of Food
Fat and protein take more energy to metabolise than carbohydrates. Protein requires 12% more energy to digest than carbohydrates, which is equivalent to 220 Calories/day. Calories out is higher for the same Calories in from carbohydrates so the energy balance equation is more likely to be negative.Calories in alters Calories out.
- Ambient temperature
If the weather is cold, energy expenditure rises as you use more energy to stay warm. You are hungrier and eat more. Calories out alters Calories in.
By far the greatest component of calories out is your BMR. Exercise increases your energy expenditure but compared to BMR the % increase is small. Exercise suppresses appetite during and immediately after but then it increases (due to homeostasis) and you will eat more.
Again – you cannot outrun a bad diet. Diet is far more important than exercise for weight loss (although of course exercise has vast benefits in other ways). Calories out alters Calories in.
- Appetite and satiety
Fat and protein both reduce appetite and induce a feeling of satiety (having had enough to eat) compared to carbohydrates, which increase appetite. So Calories in are naturally lower on a low carbohydrate, moderate fat and protein diet compared to the low fat, high carbohydrate diet advised by the NHS and the USDA. Calorie controlled diets are by definition low fat/high carbohydrate (because fat is high Calorie) and they make you hungry!
Calories in alters Calories in.
- Insulin resistance
If our diet is carbohydrate based, glucose levels and hence insulin levels are constantly high. Insulin receptors downgrade their sensitivity. More insulin is released to remove glucose from the bloodstream. Fat cells take up more energy and store it as fat, driven by high insulin. Muscle and other cells are deprived of energy and are “hungry”. We are hungry. We eat more (carbohydrate). Glucose and insulin levels rise. Fat cells get fatter. We get fatter and hungrier.
Think of it as a “weight thermostat”. High carbohydrates drive a high insulin level, which resets our weight thermostat to a higher weight – the higher the insulin level the fatter we get.
In contrast, in non insulin resistant people, if they overeat their BMR rises (from 1800 Calories/day to 2700 Calories/day in one study of overfeeding prisoners) to burn off the extra energy as heat and keep their weight at their set weight level.
Due to insulin resistance, our fat cells take up too much energy and our other cells are deprived so we are hungry. We don’t get fat because we overeat, we overeat because we are fat.
Calories in alters both Calories in and Calories out.
- Resting Energy Expenditure (REE)
People with insulin resistance can have a reduced REE i.e. they are more efficient at not expending energy, reducing their daily energy requirement by around 200 Calories/day, as their fat-free mass uses fewer Calories. Calories in alters Calories out.
Calories in/ Calories out and the energy balance equation is flawed
Weight gain/loss is not as simple as changing either Calories in or Calories out in isolation.
Counting Calories will not help with weight control and is actually detrimental.
All Calories are NOT the same.
Obesity is not a behavioural failure.
Obesity is a hormonal disorder of fat regulation.
Fat is not an inert energy store, it’s an active body system which is constantly taking in and releasing fat all day long.
Control of fat regulation is hormonal.
Many hormones cause fat release but only insulin causes fat storage.
Obesity is a hormonal imbalance of insulin:
High insulin = fat accumulation
Low insulin = fat release
Dietary carbohydrates and sugars drive insulin drives fat accumulation
Overeating is a symptom not a cause of obesity
Eating less as a cure for obesity fails
Exercise alone is not enough to prevent fat accumulation
Lowering insulin levels is the key to staying lean
So how do we lower insulin levels?
- What to eat
Avoid carb-rich foods, starchy foods, sugary foods, soft drinks, beer, sweets etc.
Avoid “low fat” foods which contain sugar to make them palatable eg low fat yoghurts
High quality protein (eg egg, quality meat) raises insulin less than processed meats
Increase your consumption of natural fats and fibre
Eat real food – grass fed meat/fish/seafood/eggs/fruit/vegetables/nuts/seeds
Carbohydrates drive insulin drive weight gain. Avoid them.
- When to eat it
Eat at regular intervals if you are hungry. Don’t bother with breakfast if you’re not hungry. Skip a few meals if you’re not hungry. Do not snack in between meals as this keeps insulin levels higher for longer – better to let insulin levels drop before the next meal. Don’t eat a lot before bedtime.
Cortisol is the “fight or flight” hormone released in times of stress to enable us to survive a threat. In the short term it raises blood glucose and usually works in opposition to insulin (which lowers it). However, in chronic, long term stress (work/commuting/family issues/illness) cortisol levels are chronically elevated so glucose levels are constantly high – and this leads to constantly elevated insulin levels. Insulin resistance and weight gain follow. High cortisol causes weight gain via high insulin levels (Cushing’s disease). Low cortisol causes weight loss (Addison’s disease).
So stress causes weight gain. Chill.
Sleep deprivation is a major cause of stress because it increases cortisol levels. In 1910, people slept on average 9 hours/day. Now more than 30% of us get less than 6 hours/day and shift workers even less. Sleeping 5-6 hours/day or less is associated with a 50% risk of weight gain. The point at which weight gain starts is less than 7 hours/day. Sleep 7 hours/day or more.
Exercise is a short term stressor and the adrenalin and cortisol released in response to physical activity opposes insulin so that the muscles can take up glucose from the blood. Also exercise reduces stress long term, reducing cortisol levels and hence insulin in between exercise sessions and aiding sleep.
Exercise increase builds muscle, increases muscle cell insulin sensitivity and reduces visceral fat. Exercise reduces insulin resistance.
The positive effects of exercise are due to the positive effects on our metabolism, NOT the Calories expended in exercising.
- Intermittent fasting
Part of our evolutionary past – of course we didn’t eat 3 meals a day at regular times when we were hunter-gatherers – we ate when food was available. Many meals were missed, often for days. Intermittent fasts of 12-48 hours are very effective at lowering insulin levels and increasing insulin sensitivity. GP advice should be sought before fasting as care is needed if you are diabetic, have other health issues or are training heavily.
Whilst the cause of obesity (and many other metabolic diseases) is indeed poor food and lifestyle choices, the current advice on reducing Calories in by eating less and increasing Calories out by exercising more fails to control weight gain or achieve long term weight loss.
Instead the advice should focus on healthy food choices NOT calories and lifestyle changes which reduce insulin levels.
And finally: Susan Sontag, an American intellectual, said of obesity in 1978:
“Theories that diseases are caused by mental states and can be cured by willpower are always an index of how much is not understood about the physical terrain of a disease”.
Additional studies etc:
In 2007, Stanford University conducted an “A TO Z Weight Loss Study”. Subjects were instructed to eat as much fat and protein as they wanted but avoid carbohydrates i.e a high fat, high saturated fat diet. They were compared with those on a low fat, low saturated fat restricted calorie diet. Those who ate mostly fat and protein not only lost more weight, but also other health parameters improved, namely:
- HDL went up
- LDL went up
- Trigycerides went down
- Blood pressure went down
- Total cholesterol stayed the same
- Risk of heart attack decreased
Another Stanford University study compared a high protein diet with a high carbohydrate diet.
Diet 1: 45% protein/35% carbs/ 20% fat – insulin metabolism improved
Diet 2: 60% carbs/20% protein/ 20% fat – insulin metabolism worsened
Evidence for hormonal control of weight includes George Wade’s study of ovariectomised rats in 1970.
Gp1: ovaries removed, free access to food, rapidly obese, activity levels unchanged
Gp 2: ovaries removed, controlled diet, rapidly obese but sedentary
Gp 3: Ovaries removed, given oestrogen, normal weight and activity levels
Conclusion: ovariectomised rats have low oestrogen levels, higher insulin, their fat gets fatter and they overeat to compensate. If calories are restricted as in gp 2, they become sedentary. Oestrogen supplementation keeps the ovariectomised rats a normal weight with normal activity levels. Obesity, appetite and activity levels are hormonally controlled.
Zucker rats: Bred to be clinically obese. These rats stay obese even in the face of starvation, using up their muscles instead for energy. No matter how little these rats are fed, they remain obese to death.
- “The Obesity Code” (2016) by Dr Jason Fung
- “Nutrition and Physical Degeneration” (1939) by Weston A Price DDS with many reprints
- “Pure, White and Deadly: The Problem of Sugar” (1972) by Professor John Yudkin
- “The Paleo Diet” (2011) by Dr Loren Cordain
- “The Paleo Diet for Athletes” (2012) by Dr Loren Cordain and Joe Friel
- “The Case Against Sugar” (2017) by Gary Taubes
- “Fat Chance: The Hidden Truth About Sugar, Obesity and Disease” (2014) by Dr Robert Lustig
- “Human Evolution, Diet and Health-The Case for Paleolithic Nutrition” (2008) Mark Hines
- “It is time to bust the myth of physical inactivity and obesity: you cannot outrun a bad diet” by Malhotra/Noakes/Phinney British Journal of Sports Medicine 23/4/2015
- “The Great Cholesterol Myth” (2012) Bowden/Sinatra
- “The Primal Blueprint” by Mark Sisson (2012)
- “Why We Get Fat and What To Do About It” by Gary Taubes (2012)
- “The Great Cholesterol Con” by Dr Malcolm Kendrick (2008)
- “Western Diseases: Their Emergence and Prevention” Hugh Trowell and Denis Burkitt (1981)
- “Rebuilding the Food Pyramid” by WC Willett and MJ Stampfer (Harvard School of Public Health) Scientific American 288 no 1 (Jan 2003) 64-71
NB:The above aims to inform so that individuals can make their own dietary choices – it does not constitute dietary advice