Caloric restriction means reducing the average daily calorie intake below usual, without malnutrition or deprivation of essential nutrients. It would not be too wrong to say that calorie restriction is “malnutrition without malnutrition”. It means reducing between 30 and 40% the typical consumption of calories , keeping all the nutrients and vitamins needed to sustain life.
Popularly speaking, it means “eating less”, not eating worse. Well observed, people eat more than is necessary for nutritional purposes: they eat encouraged by habits, by the taste of food, by the aesthetic appearance of foods, by the presence of companies, etc.
These food restriction patterns are being studied as possible ways to maintain good health and live longer. They should not be just temporary weight loss plans (diets), but lasting patterns of eating habits. The interest in its potential health and aging benefits stems from decades of research with a wide variety of animals (worms, spiders, insects and rodents), in which calorie- restricted eating delayed the onset of age-related disorders and, in some studies, prolonged the useful life of these animals.
Non-human primates are now being tested, but the results of these tests are not yet known. Preliminary results, however, suggest that calorie restriction in monkeys makes them healthier and they tend to live longer than their freely fed colleagues. For example, a new study shows that the immune system of elderly rhesus monkeys on a calorie- restricted diet resembles the immune system of younger animals.
Given these favorable results in animals, the researchers are studying whether caloric restriction also positively affects people’s health and lifespan.
Read about ” Ketogenic Diet “, ” Ketosis “, ” Fasting Diet ” and ” Malnutrition “.
What is the relationship between calorie restriction and longevity in humans?
Some studies have suggested that calorie restriction can benefit human health , however, more research is needed before we understand its long-term effects.
Some people have voluntarily practiced extreme degrees of calorie restriction over many years, believing that in this way they would preserve health and prolong life. In fact, studies of these individuals have found markedly low levels of risk factors for cardiovascular disease and diabetes , directly related to aging. The studies also found other effects whose long-term benefits and risks are uncertain, as well as reductions in sexual interest.
Many studies and clinical experience have shown that obese or overweight people who lose weight on a diet can improve their health . But scientists still have a lot to learn about how calorie restriction affects people who are not overweight, including the elderly. They also don’t know whether these eating patterns are safe or even doable in the long run. In summary, there is insufficient evidence to recommend this diet in general. If the person decides to follow you, you should be closely monitored by a doctor or nutritionist .
Caloric restriction may or may not extend the total number of years that a human can expect to live, but it undoubtedly increases the number of years that a person can expect to remain healthy. Reducing or delaying age-related illnesses until the end of life would represent a huge improvement in the quality of life for many, if not most, of the elderly.
How does caloric restriction act?
Scientists still don’t know why calorie restriction delays age-related illnesses and prolongs the lifespan of laboratory animals. In them, caloric restriction affects many processes that are related to the regulation of the rate of aging, such as inflammation , metabolism of sugar , maintenance structures of proteins , the ability to provide energy for cellular processes and modifications in DNA. Another process that is affected by caloric restriction is oxidative stress, which is the production of toxic by-products of oxygen metabolism that can damage cells and tissues.
However, we still don’t know all the factors that are responsible for the effects of caloric restriction on aging and we don’t even know if other factors also contribute. But, apart from other factors, the organic energy-producing machine has to work less and possibly with less wear and tear.
During caloric restriction, as during fasting, the body consumes glucose and glycogen as long as they exist, then turns to the fat stores , which are released in the form of ketones. These chemicals help cells (especially brain cells ) to continue their work at full capacity. The researchers think that because ketones are a more efficient source of energy than glucose , they may protect against aging-related decline in the central nervous system . In addition, ketones can also inhibit the development of cancer , because cells malignant cells cannot obtain energy from ketones.
Studies show that ketones can also help protect against inflammatory diseases and reduce the level of insulin in the blood , which could protect against type 2 diabetes mellitus , which usually affects older people. But on the other hand, many ketones in the blood can also have harmful health effects . This is one of the reasons why researchers want to understand more about how calorie-restricted diets work, before recommending them.
Although calorie restriction diets are difficult to maintain, the study of calorie restriction mechanisms is very important.