Why eating less and moving more is not the solution to sustainable weight loss. In this post Dr Trudi Deakin, CEO of the charity Xpert Health, explains how weight loss is not a simple case of calories in verse calories out, and how a high carb diet is linked to obesity and insulin resistance.
Why is obesity an epidemic?
We have all heard reports in the media about the “obesity epidemic”. Currently around two-thirds of the UK population are overweight and a quarter are classified as obese, and these numbers are expected to continue rising. Why do you think this is the case?
The common belief is that the increasing prevalence of overweight and obesity is because we are eating more and moving less.
It is thought that people are consuming more food and living more sedentary lifestyles, leading to a positive energy balance. What do you think “energy balance” means?
The theory assumes that a calorie is a calorie and that weight management is all about calories in versus calories out. A positive energy balance is when the calories in exceed the calories out, which is what many people believe leads to weight gain.
So by this logic the only way to lose weight is to eat less and move more. Many people have had success in the short term trying to lose weight by this method, but eventually almost always end up putting weight back on. Why do you think this is?
Why traditional diets don't work
Trying to lose weight by cutting calories generally leads to elevated hunger, and so this kind of diet always comes down to willpower in the end. It is almost impossible to overcome the biological urge your body creates to eat when you are hungry, which you will be if your body thinks you are depriving it. Eventually nearly everybody gives in to this hunger and increases their food consumption again, leading to weight regain.
So the body releases hormones to increase hunger, and eventually these signals overcome your willpower and you revert to eating as much as you did before. What happens then?
You put the weight you have lost back on, often plus some additional weight; meaning you end up weighing more than you did before you started dieting.
Why is weight loss often followed by weight regain
Why do you think that is?
When you reduce your calorie intake your body responds by reducing your energy expenditure (basal metabolic rate, BMR) too. So when you reduce the calories in, your body reduces the calories out. The two sides of the equation are not independent. If your body has reduced your energy out and you give in to your hunger and go back to putting the same energy in you did before, then you will end up re-gaining the weight you had lost.
The reduced BMR can continue for a long period of time, even when you have started to eat normally again, so many people end up heavier than they were before.
The Calories in, calories out equation
The fact that the energy/calories in and energy/calories out sides of the equation are related is one of the main reasons that the energy balance theory doesn’t work for achieving sustained weight loss. It is also what leads to “yo-yo” dieting. What is “yo-yo” dieting?
People going through a cycle of weight loss followed by weight re-gain, often with some extra weight.
Why do you think ‘eat less, move more’ results in “yo-yo” dieting?
This happens because people think the diet was successful because they had lost weight, and that it was their own fault that they had put the weight back on because they had lacked willpower. So they try and do the same thing that “worked” before, and the outcome is the same.
The reality is the diet was never likely to be effective long term as it is almost impossible to overcome the effects of the hormones your body releases, so rather than blaming themselves for “failing” people should look to try a different approach to losing weight.
As well as these longer term effects of causing you to relapse and gain additional weight there are also shorter term effects that show that the energy/calories in and energy/calories out sides of the energy balance equation are linked. What are they?
If you increase your physical activity (energy out) then your body often responds by increasing hunger, causing you to increase your food intake (energy in).
If you reduce your food intake (energy in) your body often responds by reducing your energy levels, so you take part in less physical activity (energy out).
Nearly everyone has an experience showing that this is true, either personally or through seeing a friend or family member fail in maintaining weight loss that had been achieved through a calorie controlled diet. Another flaw with the energy balance theory is that it assumes that all calories are equal, what do I mean by this?
It assumes that all calories will have the same effect on the body, and that no matter what I eat as long as I eat less calories than I burn then I will lose weight.
What do you think, does this work?
In the short term a calorie reduced diet might work for losing weight, but that weight loss will not be sustainable.
A calorie isn't just a calorie
Is a calorie a calorie, no matter where it has come from?
Different foods have different effects on the hormones that control our hunger and energy levels.
Different foods have other different nutritional properties, for example 500 kcal from table sugar will only provide our body with energy (i.e. empty calories) whereas 500 kcal of vegetables will provide us with vitamins and minerals as well as energy. It will also provide us with a greater volume of food (which influences hunger levels), as the vegetables will be less energy dense (i.e. you need to eat more to get the same amount of energy).
What does this all mean practically?
WHAT we eat is more important than just how many calories we eat.
If we eat the right foods our body will provide the right signals to say when we are hungry or not. This makes calorie counting unnecessary.
What is insulin resistance?
One factor that may play an important role in weight management, particularly in those with impaired glucose tolerance (as in those with prediabetes/diabetes), is insulin resistance. How have we previously described insulin resistance?
The key (insulin) does not fit the lock properly.
Insulin resistance occurs when there are consistently high levels of insulin (hyperinsulinaemia). This results in a further increase in circulating insulin levels (if insulin doesn’t work as well our body has to produce more to do the same job). Insulin triggers fat storage rather than fat burning. If we cannot burn our body’s fat stores we will struggle to lose weight, or even to maintain our current weight, leading to weight gain.
What else happens if our insulin doesn’t work well (i.e. we have insulin resistance)?
We cannot move the glucose into our body cells for energy. This drives hunger as our body thinks it needs more fuel even though we have plenty that we just can’t use (sometimes this is referred to as “starvation in the midst of plenty” and can be compared to putting a padlock on the fridge door!). Our energy levels are low because we are not able to burn the fuels (glucose or fat) that we have available.
A high carb diet is linked to insulin resistance
So if our insulin levels are high we will struggle to lose weight, even if we are not eating a large amount of food. How can we address these high insulin levels and insulin resistance?
The best way to do this would be to limit the AMOUNT of carbohydrate we are eating, or to increase the amount of time between meals to allow insulin to drop to resting levels for longer periods of time.
Featured Image: Aetiology of insulin resistance ©X-PERT Health 2018