Weight Loss -- Why Reducing Calories Is Not The Whole Story
Add the calories up that you take in in your food and drink, subtract the calories you expend in your physical activities, if the answer is a positive number you'll put on weight and if it's a negative number you'll lose weight.
The trouble is, your body doesn't see it like that. If it were that simple, early Man would never have survived from one unpredictable meal to the next. He survived because his body had a mechanism which would store energy when food was plentiful and release it again when it was scarce. His body also had a way of recognizing when energy intake was low, and economizing on its use of fuel. These two mechanisms were his blood sugar/insulin control system and his metabolic rate.
You differ little from early Man in your genetic makeup. Your body still retains the blood sugar/insulin and metabolic rate control system that enabled your ancestor to survive. The problem is, you probably don't eat like your ancestor. Your ancestor never had the carbohydrate-dense, highly refined foods that most of us eat so much of today, such as sugar, flour and all the manufactured products that are made with them. Unfortunately for you, your energy storage system works a little too well. You put on weight easily when you eat these carbohydrate-dense foods, because they send your blood sugar/insulin control system into overdrive. They may still do this, even when the calories you are taking in are not excessive.
Even worse, if you reduce your calorie intake to a level where you have a calorie deficit, you are in danger of triggering the other mechanism -- the slowing of your metabolic rate. This is often called 'starvation mode', but you don't have to be literally starving for your metabolic rate to slow down. And if your metabolic rate slows, your body needs less food to supply your daily energy needs. In other words, the more you diet, the less food you need.
This means that losing weight is very often a precarious balance between reducing food intake and exercising enough to produce a calorie deficit, while eating enough to keep your body from going into 'starvation mode'. And if you are one of the up to sixty per cent of the population which is believed to have a very sensitive blood sugar/insulin control system, then basing your diet on carbohydrates, especially the refined sort, may also hinder your weight loss.
The importance of these survival mechanisms is only now starting to be recognized in the medical world. It is becoming understood that losing weight is not just a simple matter of eating less. There is also mounting concern about very low calorie diets -- the sort that supply less than 500 calories per day -- because of the risk that they will depress your metabolic rate if followed long term. If you are not losing weight on a restricted calorie diet, then these mechanisms may well be at play. These and many other factors which may be preventing your weight loss are explained further in the book Why Can't I Lose Weight -- The Real Reason Diets Fail And What To Do About It.