In a long-term calorie restriction diet, individuals eat far less food than the average in a bid to outlive their expected lifespan. Backed by science done in animal models, this type of diet often appeals to people who are interested in technology and futurism. According to "New York Magazine," about 1,400 people currently follow a long-term calorie restriction diet.
Purpose
The main purpose for following a long-term calorie restriction diet is to try and extend the lifespan. In animal studies, restricting the caloric intake of mice, rats and monkeys extended those animal's lifespans by 10 to 60 percent, depending on the age at initiation of the diet. However, since humans have such long lifespans, no studies have yet been completed on people. Proponents of calorie restriction also maintain that the diet protects them from chronic diseases such as diabetes, cancer and heart disease. This type of diet may also be used for weight loss.
Description
According to MayoClinic.com, a calorie restriction diet is defined as consuming 20 to 30 percent fewer calories than would normally be recommended for your age and activity level. Someone on a long-term calorie restriction diet will appear thinner than most people but should not be malnourished, since the diet contains an adequate amount of vital nutrients.
Mechanisms
According to the "New York Magazine" article "The Fast Supper," scientists remain uncertain about the mechanisms behind calorie restriction's success at increasing the lifespan of laboratory animals. Some suggest that living in a state of near-starvation triggers a survival reflex within cells. Other scientists maintain that the effect comes from a lowered rate of normal wear and tear on bodies that spend less time digesting and processing food. In an August 2005 article in PLoS Medicine, the idea is put forth that simply restricting portions of the diet, such as protein and fat, may confer the same benefits that a full calorie restriction diet does, but these ideas are still under study in humans.
Results
Research on individuals pursuing a long-term calorie restriction diet has already shown promise in improving blood pressure, blood glucose levels, cholesterol levels, body fat percentage and overall weight, according to MayoClinic.com. However, the mechanisms at work in rodents may not fully apply in humans and people may only be able to achieve a lifespan extension of 4 to 17 percent maximum.
Safety
Older individuals and people who are already thin may incur more risks when attempting a calorie-restricted diet. People on this type of diet often experience a loss of bone and muscle mass and may develop changes in hormone levels. When first beginning a calorie-restricted diet, individuals should be careful not to lose too much weight too quickly, no more than 5 lb. per month or risk losing muscle, including cardiac muscle from the heart.
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