Previous studies have suggested that calorie restriction can increase longevity and decrease oxidative stress (DNA damage) in a variety of species. Now research reports that calorie restriction in humans may provide similar benefits seen in animals, including low levels of insulin and reduced DNA damage. These markers are associated with longevity and a lower risk of age-related diseases including atherosclerosis, cancer, diabetes, and Alzheimer's.
The randomized controlled study, published in the Journal of the American Medical Association, investigated the effect of six months of calorie restriction, with or without exercise, in overweight men and women. Researchers at Louisiana State University, in Baton Rouge administered a weight maintenance diet (control), a calorie restricted diet (25% restriction from calories), a calorie restricted diet plus exercise (12.5% restriction from calories plus 12.5% increase in exercise energy expenditure), or a very low calorie diet, to 48 healthy, sedentary men and women with a body mass index (BMI) of 25 to 30, for six months. Weight measurements, core body temperature, 24 hour energy expenditure, and blood levels of insulin, glucose, DHEA, protein carbonyls, thyroid hormones and DNA fragmentation were obtained from the participants at the beginning and end of the study.
Researchers found that the control group lost 1 percent of their body weight, the calorie restricted group lost 10.4 percent, the calorie restriction with exercise group lost 10 percent, and the very low calorie group lost 13.9 percent of their body weight. Insulin levels, 24 hour energy expenditure, thyroid hormone levels and DNA damage were significantly reduced in all groups except the control group, although glucose and DHEA remained unchanged. Body temperature was lowered in the calorie restriction groups, but not in the control or very low calorie diet groups.
The study findings suggest that a calorie restricted diet may increase longevity and lower the risk of age-related diseases including atherosclerosis, cancer, diabetes, and Alzheimer's. "Our results indicate that prolonged calorie restriction caused: (1) a reversal in 2 of 3 previously reported biomarkers of longevity (fasting insulin level and core body temperature); (2) a metabolic adaptation (decrease in energy expenditure larger than expected on the basis of loss of metabolic mass) associated with lower thyroid hormone concentrations; and (3) a reduction in DNA fragmentation, reflecting less DNA damage," the study authors write.
REFERENCES:
1. Heilbronn LK et al. Effect of 6-Month Calorie Restriction on Biomarkers of Longevity, Metabolic Adaptation, and Oxidative Stress in Overweight Individuals: A Randomized Controlled Trial. JAMA. 2006 Apr5;295(13):1539-1548.
Posted by Elaine Gavalas on July 12, 2006 02:22 PM
