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A new research at the University at Buffalo has shown that a severely restricted diet can maintain physical fitness into advanced age, slowing the seemingly inevitable progression to physical disability and loss of independence.
The research was done using a rat model of lifetime caloric restriction, and it showed that the diet reduces the amount of visceral fat, which expresses inflammatory factors that in humans cause chronic disease and a decline in physical performance and vitality across the lifespan.
"This is the first study to report that caloric restriction reduced production in visceral fat of the inflammatory cytokine IL-6 and enhanced performance on overall physical function assessments," said Dr. Tongjian You, assistant professor of exercise and nutrition sciences in the UB School of Public Health and Health Professions and principal investigator.
"In addition, rats that ate a normal diet lost a significant amount of lean muscle mass and acquired more fat, while calorie-restricted rats maintained lean muscle mass as they aged," he added.
The research involved male rats in three age groups -- 18, 24 and 29 months, comparable to ages 50-70 years in humans -- which had been fed either a normal or 40 percent calorie-restricted diet from birth.
The animals were put through tests to determine grip strength, muscle tone, stamina and swimming speed.
The researchers also collected data on whole body mass, lean body mass, fat mass, percent body fat, the ratio of fat-to-lean body mass, amount of visceral fat and the amount of pro-inflammatory cytokines and C-reactive protein, a marker of chronic inflammation.
It was observed that mice on the restricted calorie diet had significantly higher physical performance scores than animals fed a normal diet. They also had less fat, a lower fat-to-lean ratio, and lower adipose tissue secretion of IL-6 and circulating levels of C-reactive protein.
Dr You said that the stumbling block on this path to remaining forever young is that humans could not adhere to such a severe diet.
"Based on an average of 2,000 calories per day for adult women and 2,500 for men, cutting by 40 percent would mean surviving on 1,200 and 1,500 calories per day, respectively," he said.
"It's very difficult for people to maintain that type of diet for short periods of time, and it would be nearly impossible over a lifetime, while staying healthy. Starting on a diet like that in the senior years would be harmful," he added.
According to him, the new findings point towards the achievability of a more moderate form of caloric restriction, which may have positive effects on specific oxidative stress and inflammatory biomarkers.
"Preclinical testing of this 8 percent regimen could be informative and beneficial in translating to humans," he said.
The study is published in the October issue of Journals of Gerontology Series A: Biological Sciences and Medical Sciences.
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