What is Calorie Restriction all about?

Calorie Restriction Explained

Calorie restriction is a dietary regimen that most people would think of as new but has actually been studied for over 70 years now. The main principle of calorie restriction is to provide a person with restricted calories but is compensated with high nutrient contents dispensed by controlled portions of food.

Calorie restriction, when not related to malnutrition, is believed to improve lifespan expectancy and actually retards the aging process. But as time goes by, this belief is now turning into reality as backed up by credible data collected from decades of work with fungi, rodents, fish, dogs and even primates. Still, however, we cannot leave out the fact that despite the positive effects that calorie restriction may bring to primates, its long-term effects has not been well established due to the length of time the study has to undergo. Calorie restriction is now associated with positive changes in the metabolic, hormonal and functions of the human body but studies cannot determine the exact amount of calorie consumption or body fat mass that can be linked to optimal health and increased lifespan in humans.

Another thing that concerns calorie restriction is that even moderate amounts of calorie restriction may be more harmful than beneficial to specific human populations such as those individuals who are lean and have low body fat percentage.

Calorie Restriction Studies

Current studies have taken into good consideration the hypothesis that calorie restriction acts by decreasing insulin levels in the blood and thereby decreasing the rate of cell degradation in the body. But calorie restriction affects other areas of health and the physiologic functioning of the body and is, therefore, not known whether or not insulin is the real main concern.

In human trials, calorie restriction has exhibited lower levels of blood cholesterol, fasting blood glucose and blood pressure. In calorie restriction, energy intake is taken into minimum but rich amounts of vitamins, minerals and other valued essential nutrients must be consumed.

A small study made at the Washington University School of Medicine in Saint Louis, Missouri looked through the effects of following the idea of calorie restriction of between 10 to 25% lesser calories intake than the common Western diet which amounts to more than the normal required energy intake. The Body Mass Index (BMI), a measure of a person’s weight in relation to his or her height, was noticeably lower for the calorie-restricted group when examined in contrast to the control group. The BMI of the control group are very similar to the average BMI values for middle adults in the US.

Observed Benefits of Restricting Calories

Everyone who was on calorie-restricted diets immediately experienced significant reductions in their BMI right after starting their diet. Almost all of the decrease in BMI happened in the first year of diet. It was also observed that these people had lower total blood cholesterol levels and low density lipoprotein (LDL or bad cholesterol) levels and a consequent increase in high density lipoprotein (HDL or good cholesterol) levels.

These good results were found to occur primarily during the first year of dieting. The experimental group (calorie-restricted group) even has lower but normal blood pressures, fasting blood glucose, and fasting insulin aside from the decreased Body Mass Index.

It was also observed that the calorie-restricted group had significantly low triglyceride levels. It was so low that these results turned out to be similar to the lowest 5% of Americans in their twenties. This is unusually remarkable considering that individuals under the calorie-restricted group were actually between the ages of 35 to 82 years. The control group, on the other hand, approximately have values aligned with the national average of US.

Fasting plasma insulin levels and fasting blood glucose levels are factors that predict the occurrence of diabetes. On another note, excessive caloric restriction can eventually result to malnutrition, leading towards anemia, diarrhea, nausea, and difficulty in maintaining activities of daily living due to weakness, lethargy and dizziness that may occur. This study was publicized in Journal of American Medical Association, March 2007 issue. By the year 2009, another study has shown up stating that calorie restriction can have positive effects on the cognitive functioning of humans in the form of enhancing memory in normal to overweight elderly. Another is that moderate calorie restriction has relations to decreasing the risk of age-related Sarcopenia, a form of muscle wasting, in primates.

Although forceful by nature, these studies made use of borderline to slightly overweight subjects as the control group, which is the mean in some countries. It is still ambiguous if the same results would show using subjects who are not overweight.

What were shown earlier were positive effects of calorie restriction to the body but this dietary regimen is devoid of health-related issues and concerns. By continuously consuming restricted levels of calorie, an individual can become underweight but the study concerning this matter focused entirely on the Body Mass Index and not the diet. Unless metabolism is slowed by some way, calorie restriction may result in starvation.

Risks of Calorie Restriction

When persisted in prolonged periods, the body may eventually burn the lean tissue of the body with its fat reserves in order to compensate for the reduced energy intake. This form of starvation, in turn, results in lethargy and decreased physical activity ultimately leading to decreased muscle mass. Another issue that was observed is the resulting weakened immune system.

When reducing calorie intake for prolonged periods, the absorption of essential nutrients, such as fat soluble vitamins, A, D, E, and K, may also be decreased because they require fats for proper absorption and other nutrients generally linked with high calorie food. Prolonged decreased levels of blood glucose can lead to neuroglycopenia, a state of lowered glucose in the brain resulting into alterations in comprehension, judgment and behavior.

Summary

Summarizing all of this information, the dietary regimen of calorie restriction provides positive effects in the functioning of the human body but there still are negative impacts brought about by CR. Research is still ongoing about calorie restriction and there is still so much to be learned from it. As for whether or not you should try this dietary regimen, consulting a physician is of utmost priority since calorie restriction is not for everyone.

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