Nutrition: Fat retention

Every year people spend billions of dollars exercising, dieting, and taking miracle cures that will reduce their weight and keep them slim. The weight-loss and fitness industries thrive on this, because they know that no matter what people do, they will eventually be back again.

Weight loss and gain is based on one simple principle, our bodies store excess energy as fat, and provide missing energy from fat. If we eat more than we use, we gain weight; if we eat less than we use, we lose weight. The mechanisms involved are simple, but not as simple as most people think.

Real weight

We can gain or lose weight in various ways. Drinking a lot of salted water or eating a huge meal can immediately add a few pounds on the scale, while heavy sweating and using laxatives can immediately remove a few pounds, but this isn't real weight. Neither is muscle weight; body builders can add a hundred pounds of muscle but no one considers them to be fat.

We'll use weight to refer only to stored body fat.

When our food supplies us with more energy than we use, the excess energy is stored in our fat cells. And when we use more energy than our food provides, the missing energy is taken from our fat cells. These fat cells grow and shrink as fat is added to them or removed from them. If they should fill up, more fat cells are produced to store the excess energy.

Weight loss

There is a natural limit to the amount of weight anyone can lose in one day. If our normal activities require 2000 Calories per day, and we exercise and burn another 2000 Calories, that's the equivalent of about a pound of fat. But 2000 Calories is a lot of exercise, and this assumes that we eat nothing at all. So it's fair to say we can lose at most one pound per day.

Initial weight gain

If we were to eat a massive amount of food in one day, our bodies couldn't possibly process it all and most of the unused calories would remain undigested. Eating ten pounds of fat in one day will not cause us to gain ten pounds of body weight; there is a limit to how much fat our bodies can store at a time. Everyone is different, but for convenience let's say that we can gain at most one pound per day.

Losing weight

Let's suppose we currently weigh ten pounds more than we would like to. To reduce that weight, we simply need to use more energy than we eat.

Many people promote exercise programs as a way of using more energy. Moderate exercise is definitely a good way of keeping our muscles in tone, our bones strong, and our bodies limber, but it really isn't an efficient way of losing weight. Many hours of hard work are required to burn off a single pound.

You can exercise your body by walking on an elliptical trainer for five hours, or you can exercise restraint by walking away from a Big Mac with medium fries and soft-drink. Either way saves you about a thousand Calories. Which is easier?

Yes, do get some exercise; in the long run it will make you feel better and be healthier. But to lose real weight, what you need to exercise is restraint. You need to eat less. It's not easy, but it's a lot easier than running weekly marathons, and it's the only way that works.

Regaining weight

Now suppose that after several months we have lost those ten pounds and we feel great. Can we quit the diet and start eating like we used to again? Obviously not. We have to eat enough to supply our energy needs, but no more than that. If we eat more than that, we'll regain the weight.

But it's actually worse than that.

When we lost weight, we didn't lose ten pounds of fat cells. What we lost was ten pounds of fat from our fat cells. We still have the same number of fat cells, they are just no longer full.

What this means is that if we eat too much in one day, the excess energy can very easily be stored as fat. We don't need to grow new fat cells, so the original limit of one pound per day no longer applies. If we eat too much we will very rapidly gain weight until we have regained all ten pounds, and only then will the rate of gain slow down.

Our bodies effectively remember how fat we used to be and will have a natural tendency to regain that weight. And after that, if we slowly gain even more weight, that will be our body's new target weight.

We spent years gaining weight in the first place, and many months and hard work losing it, but it can all come back again in a few weeks.

Food addiction

This mechanism is very similar to a drug addiction. Our body craves something, when we feed that craving we feel better but are actually hurting ourselves, and the more we do it, the stronger our addiction becomes.

But it's actually worse than that.

With addiction to alcohol, tobacco, or other drugs, there is really only one solution. Drug addicts can never consider themselves to be cured, only recovering. The craving will lessen, they will be able to control their behaviour, but they will always have the addiction. The only solution to their addiction is total abstinence.

Imagine an alcoholic being able to restrict consumption to just one drink a day. It is possible, but it would require an incredible amount of will-power and self-respect. Very few should attempt it, and even fewer could succeed.

But if what one is addicted to is food, continuing to eat is exactly what one has to do; total abstinence is not possible.


The weight-loss industry understands all this perfectly. Eat slightly less than you need and you'll lose weight slowly; eat slightly more than you need and you'll gain weight quickly. They know that they can help people to lose weight once they have decided that that's what they want to do. But they also know that once they have lost it, almost everyone will quickly regain all the lost weight in the following months. And perhaps they hope that people will have gained even more weight by the time they return so that they can work with them for even longer this next time.