Calorie Restriction - A No Win Proposition!

We have a very advanced and intricate array of metabolic checks and balances. Among these is something called the survival mechanism, which is responsible for the regulation of your metabolic rate in response to caloric intake.

Your body has unique capabilities

The human body is much more sophisticated than many people realize. In order to survive through food shortages, extreme weather conditions, the constant attack of viruses and bacteria, and other threats to human existence, we have developed a very advanced and intricate array of checks and balances. Among these survival mechanisms is regulation of metabolic rate in response to caloric intake.

Natural Safety Mechanism

When caloric intake is restricted, the body compensates by reducing metabolic

rate. Consequently, fewer calories and less fat is burned.

Much obesity research has been directed at defining the physiological mechanisms involved in fat regain subsequent to fat loss, because researchers believe that this avenue of investigation may yield treatments or a cure for obesity.

Leptin has generated more questions than answers

Along this same thought, the discovery of the hormone-like substance Leptin, produced by fat cells under the direction the "ob" gene, created quite a stir in the research community a several years ago. Since then, a profusion of studies have been performed, which have generated more questions than answers about this puzzling substance.

Leptin levels are higher in obese individuals and are altered by weight loss.

However, while it's highly probable that leptln plays an important role in body fat regulation generally, lipoprotein lipase and thyroid hormones appear to be more instrumental in regulating metabolism in response to short-term changes in caloric intake.

- Lipoprotein lipase, a lipogenic (fat-storing) enzyme, increases markedly when calories are restricted.

- At the same time, production of the thyroid hormone (T3) decreases.

The down regulation of T3 slows metabolism, resulting in preservation of muscle mass but also body fat.

The metabolic adjustments to reduced caloric intake make sense from the standpoint of survival: the slower one's metabolism, the more "mileage" one gets out of a given quantity of stored energy (fat), and the longer one remains alive during a famine (and the longer one remains alive during a famine, the greater the likelihood that conditions will change, food will be found, and death will be averted).

What happens when you increase your caloriic intake?

When you resume normal eating, lipoprotein lipase activity remains elevated and metabolic rate remains depressed, causing you to quickly regain the lost fat, and maybe even a little extra fat as insurance against the next "famine."

Stated differently, the rate of fat storage is increased after a period of calorie restriction, and it stays that way until the pre-diet level of body fat is re-established.

This demonstrates the futility of trying to achieve permanent fat loss solely by means of calorie restriction.

In addition, you invariably lose precious muscle tissue. This further retards metabolism and adversely affects the shape, tone, and functional ability of the body, muscle loss resulting from restrictive dieting ranges from 20% - 40% of total weight.

With this muscle loss to fat loss ratio, body composition may only improve marginally while on the diet. And when the diet ends, and the fat returns but the muscle does not, body composition worsens.

Bottom Line:

In this vicious cycle, you go from being fat and flabby, to being less fat but more flabby, to ultimately becoming fatter and flabbier than ever.

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