Most Americans consume a significant amount of fatty meats, processed foods and sugar. The Mediterranean diet, meanwhile, is high in fiber, whole grains, legumes and olive oil while low in red meat and sugar.
The study’s aim is to determine whether health and longevity are influenced more by healthy eating or by weight loss.
“We want to know whether markers of health will improve more in people on the Mediterranean diet than in those eating a typical American diet,” said Luigi Fontana, MD, PhD, research professor of medicine and co-director of Washington University’s Longevity Research Program. “Many people lose weight when they consume a Mediterranean diet, but it’s difficult to determine whether their markers of health and longevity improve because they’re eating healthier food or whether those positive changes result from weight loss. This study will begin to answer those questions.”
Fontana’s team will measure lipids, glucose, inflammation and other indicators of cardiovascular health and longevity.
Unlike many diet studies, this one will exclude volunteers who need to lose a substantial amount of weight. The researchers will ask subjects to keep their weight stable, at least initially.
Later, the study will incorporate intermittent fasting. Participants — whether they are eating a Mediterranean diet or an American diet — will be asked to fast two days a week. They won’t be asked to completely abstain from food on their fasting days, however. Salads and nonstarchy vegetables will be allowed at dinnertime.
Animal studies have shown that intermittent fasting has many of the same benefits as chronic calorie restriction (consuming reduced calories while continuing to get adequate nutrition). Curtailing calorie intake, while maintaining nutrition, has been found to keep animals healthy and extend their lifespans.
“But nobody really knows what happens when you change the quality of a diet and maintain weight,” Fontana said. “We want to test what happens if you improve the quality but don’t lose weight.”
Later in the study, the researchers will compare markers of metabolic health, inflammation and longevity as subjects on both diets lose weight by combining intermittent fasting with either the Mediterranean diet or a typical American diet.
Fontana is recruiting volunteers 30-65 years of age who don’t smoke and are of normal weight or slightly overweight. At the start of the study, researchers will measure lipids, sugar and inflammatory molecules in the participants’ blood; cardiovascular health; and body fat.
Those who qualify will be randomly assigned to eat the same foods they had been eating or to switch to a Mediterranean diet. After two months, the researchers will take more measurements related to aging and metabolic health, and both study groups will be asked to begin fasting two days per week.
On the other five days, participants will consume the same number of calories they normally would. With the intermittent fasting, Fontana expects both groups will lose weight.
Those randomly selected to eat a Mediterranean diet will have their food provided by a research kitchen. Both groups will be taught by a dietitian how to fast intermittently.
Study-related tests and consultations will be provided free of charge. For more information or to volunteer, call 314-362-2399 or e-mail firstname.lastname@example.org.