64% of the UK population is overweight or obese and 2 in 3 women have dieted in the last year.
As someone who has dedicated her adult life to study the science of food, nutrition and eating habits I often wonder why is it so hard to keep the weight off for a long period of time after dieting. After extensive research of the past few years I can tell you that I am closer than ever to an answer!
Obviously how much you weigh and what your BMI (body mass index) is depends on how much you eat, what the composition of the food that you consume is and also how much energy you burn throughout the day.
What many don't realise however is that hunger and the “need” to eat is regulated by our brain (namely by the hypothalamus) without us even realising. The brain you see, has its own sense of how much you should weigh. This is known as a set point (set point theory) which has a range of about 10-15 pounds.
Lifestyle choices and “dieting” can help you move this set point up or down within this range but it is much harder to go outside of this range. There are many signals in the brain that tell the body to lose weight and the same amount of signals tell the body to gain weight. I remember once listening to a Ted Talk by a neuroscientist Sandra Aamodt who described this set point theory as working a little bit like a thermostat. Just like a thermostat that keeps the temperature in your house constant when weather outside changes, the brain responds to weight loss by using powerful tools to push your weight back into what it considers normal.
So, when going on a diet (especially on a low calorie one) the brain will responds to signals from the body by adjusting hunger, activity and metabolism to keep the body weight stable as conditions change. If you lose a lot of weight your brain thinks you are starving- you become hungry and your muscles burn less fat and your metabolism goes down. People who have lost 10% of their body weight are likely to burn 300-400 calories less per day than someone who has not lost the weight. Just to put this in perspective, 400 calories is a two egg cheese omelette and two slices of toast- so a whole meal! This means that if you want to successfully diet- you will need to eat this much less per day forever. To make it even more unfair, scientists believe that set points can go up but they very rarely go down and even a temporary weight gain (for example during pregnancy) can become permanent with this new increased set point.
Diets are not very reliable. About five years after a diet most people have regained what they lost and almost half of them would have gained even more. So it seems that the typical outcome of a diet is that you are more likely to become heavier in the long run.
Diets may seem harmless but they can actually cause a lot of damage. In America, 80% of 10 (yes, 10!) year old girls have admitted at least once being on a diet. Obsession with dieting and weight at this age can lead to eating disorders and other psychological problems.
Our brains work to protect us and will naturally work to stop the dangerous effects of crash dieting and unsustainable weight loss.
If you are now convinced that dieting the way you have been doing it could be a problem then we need to think what we can do about it. My advice would be to ditch the diet and more importantly the diet mindset. Think of a healthy eating plan and a healthy approach to eating and adopt a sensible exercise regime. Try and use as many food groups and as many different colours of foods you can find in as many meals as possible. Have healthy snacks. Give yourself permission to (as an occassional treat) have that “bad” thing you fancy and do not deny yourself the pleasure of enjoying the foods you really like.