Eating healthily, less might lengthen lives, study says

(RNN) –  Healthy people who ate less food while getting essential nutrients improved their blood pressure, cholesterol and insulin resistance –   indicators associated with a longer life.

Researchers with the two-year National Institutes of Health study reached that conclusion. They studied 218 normal weight and slightly overweight young and middle-aged men and women who restricted their calories in comparison with 218 who ate their regular diets.

Encouraged by the results, published in the September 2015 Journal of Gerontology: Medical Sciences, a researcher added a note of caution.

“… We need to learn much more about health consequences of this type of intervention in healthy people before considering dietary recommendations,” said Dr. Richard J. Hodes of the NIH in a news release. “In the meantime, we do know that exercise and maintaining a healthy weight and diet can contribute to healthy aging.”

In laboratory animals, the researchers said, calorie restriction started in youth or early middle age usually increased life spans. In people, an equivalent trial would take decades.

“As we continue to try to unlock the mechanisms that make calorie-restricted animals live longer, we are certain that eating smaller portions of healthier food is a good idea for all of us,” said Dr. John O. Holloszy, the principal investigator at the study’s site at the Washington University School of Medicine.

Researchers had set out to test the effects of calorie restriction on the resting metabolic rate and body temperature, two factors proposed as affecting longevity.The study found a temporary, insignificant effect on resting metabolic rate and no effect on body temperature.

The calorie restriction participants lost an average of 10 percent of their body weight in the first year and maintained the weight over the second year. Researchers described that amount as “the largest sustained weight loss reported in any dietary trial in non-obese people.”

Compared to the control group, calorie restriction significantly lowered several predictors of cardiovascular disease, the NIH said:

• decreased average blood pressure by 4 percent;


• decreased total cholesterol by 6 percent;


• increased levels of HDL (“good”) cholesterol; 


• caused a 47-percent reduction in levels of C-reactive protein, an inflammatory factor linked to cardiovascular disease;


• markedly decreased insulin resistance, an indicator of diabetes risk; and 


• decreased T3, a marker of thyroid hormone activity, by more than 20 percent, while remaining within the normal range. Lower thyroid activity, the NIH said some studies suggest, may be associated with longer life span.

Although the study found no negative effects on mood (hunger-related symptoms), a few participants developed transient anemia and greater-than-expected decreases in bone density given their weight loss.

A researcher suggested a future study.

“It also would be useful to discover if calorie restriction over longer periods has additional effects on predictors of health in old age,” said Dr. Evan Hadley of the NIH, “and compare its effects with exercise-induced weight loss. “

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Eating healthily, less might lengthen lives, study says