Study Suggests Restricting Calories May Slow Aging Process

Recent research suggests that calorie restriction can slow metabolism and minimize oxidative cell damage, two key factors related to the aging process. The study was published in the journal Cell Metabolism.

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The authors write that calorie restriction “is a dietary intervention with potential benefits for healthspan improvement and lifespan extension.” They mention that this practice increases longevity in a “wide variety of, but not all, species.” There have been very few studies relating caloric intake and longevity in humans.

The study out of Pennington Biomedical Research Center in Baton Rouge followed 53 non-obese people over the course of two years. Thirty-four participants went on the calorie-restriction diet. Nineteen people, the control group, stuck to their normal dietary routines.

Participants on the calorie-restriction plan reduced their caloric intake by about 25 percent per day. Unsurprisingly, they lost 25 pounds on average over the two-year period, whereas the control group gained as much as four pounds.

However, the study was not focused on weight loss. Rather the research team, headed by clinical physiologist Leanne Redman, wanted to test how severe calorie reduction could affect the aging process.

The researchers tested subjects’ metabolic rates via gas, oxygen and carbon dioxide and how it changed over time. People on the restricted diet exhibited slower metabolisms that had become more efficient.

“Basically it just means that cells are needing less oxygen in order to generate the energy the body needs to survive,” Redman explained, “and so the body and the cells are becoming more energy efficient.”

If cells need less oxygen to burn energy, dangerous byproducts (such as free radicals) of metabolism will also be reduced.

“Oxygen can actually be damaging to tissues and cells, and so if the cells have become more efficient, then they’ve got less oxygen left over that can cause this damage,” she said. This oxidative damage is one factor that can contribute to an accelerated aging process.

The study also found that participants on the calorie reduction diet had lower blood pressure, cholesterol and triglyceride levels. Life-shortening diseases are much more prevalent when these levels are high.

Potential Issues

The study points to the perceived benefits of a severe calorie-restricted diet. However, it’s something that many people would not be able to do, let alone really want to undertake. Lower metabolic rates can also create problems.

Valter Longo, a biochemist who studies longevity at the University of Southern California, says dramatically reducing caloric intake for brief periods can lead to potential weight gain afterwards.

People would have to continually eat less after a calorie-reduced diet to maintain the weight they lost initially as a result. Longo contends that this could ultimately lead to “yo-yo” dieting, which occurs when people go off a diet, eat more, and return to their original weight or gain even more.

“For most people, if you consider 70 percent of Americans are either overweight or obese,” Longo says, “then you can see how, for most people, this would be a big problem.”

Longo also voiced concern about muscle loss and weakened immune systems in people on severe calorie restrictions.

Study Limitations

The study certainly does not prove that a severe calorie-reduced diet will directly correlate to a prolonged life. However the researchers make clear their desire for more research into the topic.

Low-calorie diets may help to stall the effects of aging
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“Interventions,” they write, “with the capacity to induce a sustained slowing of energy metabolism such as [calorie restriction] should remain a focus of longevity research because randomized clinical trials and cohort studies are lacking.”

They note that an imposed calorie-restriction for only two years “limits any extrapolation or speculation of the impact of [calorie restriction] on longevity in humans.”

However, many biomarkers associated with aging improved in participants on the calorie-restricted diet.

The researchers also write that their study was limited by the lack of information related to actual diet of the participants. They did not prescribe particular meals or specific dietary guidance, so the researchers cannot infer any diet recommendations aside from a reduction in calories.

Nevertheless, this study is further evidence that everyone should be mindful of what, and how much, they eat every day. Diet no doubt has a lasting impact on our longevity, and healthy habits can go a long way to reduce the effects of aging.