Wednesday, May 13, 2009

Calorie-restriction diet for anti-aging

Calorie-restriction diet for anti-aging
By Mayo Clinic staff
Definition
A calorie-restriction diet for anti-aging involves eating fewer calories than your body needs to maintain your normal weight — while still getting enough vitamins and other nutrients. Generally, a calorie-restriction diet may call for 20 to 30 percent fewer calories than usual.
Interest in the calorie-restriction diet as an anti-aging tool has grown as researchers have learned that restricting calories can extend the lives of animals. However, the possible role of a calorie-restriction diet for slowing the aging process in humans is still under investigation. Short-term studies have shown that a calorie-restriction diet can have both benefits and risks for humans, and it's unclear whether the diet can extend a person's life.
If you're interested in trying a calorie-restriction diet for anti-aging, consult your doctor and a registered dietitian to make sure you get enough vitamins and other nutrients.
Purpose
Proponents of the calorie-restriction diet claim that restricting calories slows the aging process, reduces the risk of various chronic diseases and leads to a longer life. If you're overweight, a calorie-restriction diet may also help you achieve a healthy weight. But a calorie-restriction diet can have both positive and negative health effects, and researchers haven't determined whether the regimen truly extends a person's life.
Diet details Research has shown the following health benefits for animals on a calorie-restriction diet for anti-aging:
Rodents that reduced their calorie consumption by 30 to 60 percent before age 6 months increased their maximum life spans by 30 to 60 percent.
Rodents that reduced their calorie intake by 44 percent as adults — age 1 — increased their maximum life spans by 10 to 20 percent.
Rodents that followed a calorie-restriction diet developed fewer chronic diseases associated with aging — such as diabetes, heart disease and cancer — or delayed the development of these diseases.
A calorie-restriction diet decreased the deterioration of nerves in the brain and increased nerve creation in animals with Alzheimer's disease, Parkinson's disease, Huntington's disease and stroke.
Some researchers say that a calorie-restriction diet triggers a survival mechanism in animals with short life spans, such as rodents, that allows them to outlive food shortages. However, it's unclear whether people may benefit from a calorie-restriction diet the same way. Some researchers estimate that a long-term calorie restriction diet may only increase a person's life expectancy by 4 to 17 percent.
Researchers haven't identified a precise calorie limit for a calorie-restriction diet. It's even difficult to make general recommendations about calorie thresholds, due to variables such as body composition, genetics, age and daily energy expenditure. Generally, however, a calorie-restriction diet may call for 20 to 30 percent fewer calories than usual. If you're interested in a calorie-restriction diet for anti-aging, talk to your doctor.
Results
Limited research on the calorie-restriction diet for anti-aging suggests that it can lead to positive changes in:
Blood pressure
Blood sugar
Body fat percentage
Cholesterol level
Weight
Research also suggests that a calorie-restriction diet can improve memory in older adults. Most of these changes also reduce the risk of chronic diseases, such as heart disease, but it isn't clear whether they'll translate to a longer life span.
Risks
The calorie-restriction diet isn't safe for everyone — particularly older adults and people who are lean. Side effects of the calorie-restriction diet might include:
Menstrual irregularities
Hormonal changes
Reduced bone density
Loss of muscle mass
If you're following a calorie-restriction diet, you can offset some losses in bone density and muscle mass through regular physical activity, such as walking or jogging, and by making sure you get enough calcium and vitamin D.
Excessive calorie restriction can cause:
Anemia
Dizziness
Depression
Irritability
Lethargy
Swelling in your legs and feet

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