To live longer, you may want to eat less.
A new study found that patients who reduced their total calorie intake had reduced blood pressure, cholesterol and insulin resistance — all factors tied to life span.
"It is encouraging to find positive effects when we test interventions that might affect diseases and declines associated with advancing age,” said Richard J. Hodes, MD, director of the National Institute on Aging (NIA), in a press release. “However, we need to learn much more about the health consequences of this type of intervention in healthy people before considering dietary recommendations. In the meantime, we do know that exercise and maintaining a healthy weight and diet can contribute to healthy aging.”
While calorie restriction did appear to have positive health effects, the 218 normal-weight and overweight patients in this study weren't cutting just any type of calorie. Calorie restriction is all about reducing daily calorie intake without depriving the body of essential nutrients. In other words, reach for the fruits, veggies and healthy proteins — not sugar-laden empty calories.
And plenty of past animal studies have found positive effects of calorie restriction, but this is among the first randomized, controlled trials to test the effects in humans, according to the National Institutes of Health.
To do so, study author Evan C. Hadley, MD, director of the NIA Division of Geriatrics and Clinical Gerontology, and colleagues asked some of the study patients to restrict their calorie intake for two years. The other patients — the control group — did not change their diets.
On average, the calorie-restriction patients lost 10 percent of their body weight over the course of this study, Dr. Hadley and team found. They were also able to reduce their calorie intake by around 12 percent. Control group patients saw little to no change in these measures.
In addition to their reduced weight, patients who restricted their calorie intake also saw improvements in health measures tied to longevity. Those included a 4 percent drop in blood pressure, a 6 percent drop in cholesterol and a 47 percent drop in C-reactive protein. High cholesterol and blood pressure have long been tied to an increased risk of heart disease. The same goes for C-reactive protein, which is a blood marker that signals inflammation.
Calorie-restriction patients also saw declines in insulin resistance. Resistance to insulin, the hormone that regulates blood sugar, is a risk factor for type 2 diabetes.
"The ... results are quite intriguing," Dr. Hadley said in a press release. "They show that this degree of sustained calorie restriction can influence disease risk factors and possible predictors of longevity in healthy, non-obese people ... Since this group already had low risk factor levels at the start of the study, it’s important to find out whether these further reductions would yield additional long-term benefits. It also would be useful to discover if calorie restriction over longer periods has additional effects on predictors of health in old age, and compare its effects with exercise-induced weight loss.”
Before making any major changes to your diet, speak to your doctor.
This study was published in the September issue of the Journal of Gerontology: Medical Science.
This research was funded by the NIA, National Institute of Diabetes, Digestive and Kidney Diseases and National Institutes of Health Cooperative Agreements. Dr. Hadley and team disclosed no conflicts of interest.