Calorie restriction (CR) is a dietary regimen that reduces energy intake without causing malnutrition. It has been a subject of scientific research due to its potential effects on body weight management, longevity, and aging-associated diseases. While the evidence in humans is still preliminary, studies suggest that CR might offer significant health benefits, including weight loss and disease remission.
Calorie Restriction and Aging
Research has shown that decreasing caloric intake
by 20-30% while meeting nutrient requirements can help remedy diseases of aging, such as cancer, cardiovascular disease, dementia, and diabetes. In humans, this reduction in calories has resulted in an average weight loss of 7.9 kilograms (17 pounds). However, due to the long lifespan of humans, definitive evidence that CR can prevent age-related diseases remains under preliminary research. The precise amount of calorie intake and associated fat mass for optimal health in humans is not yet known.
The concept of calorie restriction in the study of aging involves reducing calorie intake without incurring malnutrition. If a restricted diet lacks essential nutrients, it can lead to serious negative effects, as demonstrated in the Minnesota Starvation Experiment. This study, conducted during World War II, involved lean men who restricted their calorie intake by 45% for six months. While some metabolic adaptations were observed, such as decreased body fat and improved lipid profiles, the experiment also resulted in negative effects like anemia, muscle wasting, and irritability.
Potential Health Benefits
Calorie restriction has been associated with various health benefits, including improved lipid profiles and decreased resting heart rates. These changes suggest that CR might contribute to better cardiovascular health. Additionally, CR has been linked to lower insulin resistance, reduced levels of LDL cholesterol, and less oxidative damage to DNA. These factors are crucial in reducing the risk of chronic diseases and promoting overall health.
Despite these potential benefits, moderate amounts of calorie restriction may have harmful effects on certain population groups, such as lean individuals with low body fat. Therefore, it is essential to approach CR with caution and ensure that nutrient requirements are met to avoid malnutrition.
Ongoing Research and Future Directions
As of 2021, intermittent fasting and calorie restriction remain under preliminary research to assess their possible effects on disease burden and increased lifespan during aging. The relative risks associated with long-term fasting or calorie restriction are still undetermined. Intermittent fasting, which involves periods of no food intake except for clear fluids, could be combined with overall calorie restriction and variants of the Mediterranean diet to contribute to long-term cardiovascular health and longevity.
The ongoing CALERIE study is a significant research effort aimed at understanding the long-term effects of calorie restriction in healthy humans. This study hopes to provide more insights into the potential benefits and risks of CR, ultimately contributing to a better understanding of its role in promoting health and longevity.
