There are many reasons why maybe living with more weight than you want to one of these is because we believe that your body has physiological ‘set point’, which means that your brain has an idea of how much it wants you to weigh. We don’t fully understand what determines each person’s set point, but it is different for each person and it can change throughout life. This means that it tends to increase throughout life rather than decreasing, which can be rather depressing for anyone who is struggling with their extra body weight. It tends to be a range of weight rather than one particular body weight, so for example many people will tell me that they are able to lose weight down to a certain level but then once they stop their weight loss efforts that weight returns to a particular level that is slightly higher. This is most likely to represent their set point range or what some experts refer to as a settling point.
You brain will work really quite hard to defend your set point. It doesn’t know that you live in the 21st century and in the western world, so if you start eating less food that you need then it thinks you’re living in a famine rather than intentionally trying to lose weight. It views this as an existential threat, and as such it start fighting for you to regain weight in an effort for you to continue to survive. So at a subconscious level that you probably don’t even notice, it send you out looking for more food. It makes your favourite foods that you’re currently denying yourself appear far more palatable and it encourages you to eat even just slightly more of the food that you’re currently eating.
Your metabolic rate also reduces and your body learns to cope with less energy coming in. So if you were previously eating 2000 calories a day and you then reduce your food intake to 1800 calories a day in an effort to lose weight your metabolism simply adjusts to live on 1800 calories a day, meaning that if you want to which is your calorie intake to lose weight then you would need to reduce it even further to maybe 1600 calories or below, which your body then adjusts to again, driving the amount of food you need to eat to even just maintain your weight lower and lower, until the point where reducing your food intake in order to reduce your body weight becomes impossible.
And once you stop reducing your food intake your brain assumes that the famine is now over and set about making you regain weight to protect you from any future famine. This is the reason why many people say that after they reach their goal weight on a diet, over time they gradually regain all of the weight that they previously lost and put more on besides. This is simply your brain trying to protect you. In the past this was excellent because it really did mean that you were more likely to survive a future famine, but in our current environment it works against us.
The most effective tools we have to help people to lose weight in the UK currently all those that result in a reduction of their physiological set point. Sadly, we haven’t yet found any diet or lifestyle interventions that permanently reduces the set point. The only interventions that we have available to us that help you to genuinely lower your setpoint are medications and weight loss surgery. Diet and exercise do remain critically important when you’re trying to lose weight but if you really want to achieve significant and permanent weight loss then it’s likely that you’re going to need some form of medication or weight loss surgery.