Why is your body storing more and more fat?

I am surprised at how rarely people who hope to lose weight speculate about the forces that govern the shapes of their bodies. Why don’t people who want to be thinner start by asking themselves why they are not thin right now? They take it for granted that they are no longer thin because they have eaten too much and that becoming thin again is just a matter of eating less. They view their bodies as passive depositories, like piggy banks. Calories are deposited in the bank when food is consumed. Calories are withdrawn from the bank as energy is expended. The excess of their deposits over their withdrawals equals their fat accounts. To reduce the balance of their fat accounts, they must deposit less, or spend more, or both.

Forgive me, but this doesn’t seem like a very thoughtful analysis. Your body is not a passive fat depository. It is a life force that actively controls and regulates every aspect of its physical existence. Your body temperature similarly equals the excess of the heat energy you absorb or create over the heat energy that you lose. But if you were running a fever, you wouldn’t walk naked through the snow in an effort to lower your body temperature. You would call the doctor to find out why your body had raised its temperature. You can’t treat an undesirable symptom, like the fact that there is too much fat on your body, by attacking it directly. The symptom will only come back. You must deal with whatever is causing the symptom. Then the symptom will go away by itself.

A great deal of evidence supports the conclusion that your body actively maintains its levels of fat. If your body were just a passive fat depository, then if you stayed on a diet you would get thinner and thinner until you died of starvation, and if you never dieted, you would get fatter and fatter until you became grossly obese.

Neither of these things happens.

Not to you, not even to little babies who are allowed to eat as much as they want to and never get on a scale. Your body is not relying on you to determine how much fat it should be storing, any more than it is relying on you to determine how much muscle it should be maintaining, or how many blood cells it should be circulating, or how many hormones it should be secreting, or how much it should be growing and when it should stop.

Rather, your body has a “lipostat” that is set at a specific level of body fat, just as it has a thermostat that is set at 98.6 degrees. Your body actively responds to any sustained variation in caloric intake to maintain the levels of fat that it wants to maintain. For example, your body reduces its metabolism in response to a sustained reduction in caloric intake, and it increases its metabolism in response to a sustained increase in caloric intake. Metabolism accounts for 70% of an individual’s daily caloric expenditure. Your long-term appetite also increases in response to a loss of body fat and decreases in response to an increase in body fat. Your body controls your long-term appetite by varying the levels of appetite-suppressing chemicals, like leptin,that make you feel satiated even though your stomach is empty. Your body also responds to a sustained reduction in caloric intake by producing less thermal energy; discouraging physical activity; increasing psychological interest in appetizing foods; and inducing sensations of hunger in your esophagus and your stomach.

It doesn’t take much for your body to return its fat levels to where they’re set. An energy imbalance of 100 calories per day (the equivalent of an apple, or a light beer) is enough to change your weight by ten pounds over the course of a year. In fact, you are completely dependent on your body’s lipostat to maintain your levels of fat in the long run. From: Survival Of The Thinnest: How To Use Your Genetic Script To Stay Thin Without Dieting
by David Hariton