Older people who followed a lower-calorie Mediterranean diet and minimally exercised up to six days a week gained muscle and lost a significant amount of body fat by the end of a year and kept much of it off for three years, according to a new study.
“This study demonstrates that a calorie-controlled Mediterranean diet plus exercise does not simply produce weight loss; it results in a redistribution of body composition from fat to muscle,” said Dr. David Katz, a specialist in preventive and lifestyle medicine, who was not involved in the study.
In addition to a loss of overall body fat, participants in the study lost dangerous visceral belly fat, which could lead to diabetes, heart disease, and stroke.
While the findings of the new study are “no surprise,” they extend the benefits of diet and exercise “from mere weight loss to the mobilization of harmful, visceral fat,” said Dr. Katz, president and founder of the nonprofit True Health Initiative, a global coalition of experts dedicated to evidence-based lifestyle medicine.
Visceral fat cannot be seen. It lies behind stomach muscles, surrounding organs deep within the abdomen. If visceral fat is about 10 percent of your body’s total fat mass, that’s normal and healthy, according to the Cleveland Clinic. Too much visceral fat, however, can create inflammation, contributing to chronic disease.
“This study confirms that we can profoundly change our metabolic status,” said leading nutrition researcher Dr. Walter Willett, a professor of epidemiology and nutrition at Harvard T.H. Chan School of Public Health and professor of medicine at Harvard Medical School in Boston.
“We now need to provide a supportive environment and resources to help people make this shift because this will benefit both individuals and society as a whole,” said Dr. Willett, who was not involved in the study.
Part of a Longer Study
The research is part of an eight-year randomized clinical trial in Spain, with 23 research centers testing how diet and exercise can reduce cardiovascular risk in men and women between the ages of 55 and 75. All of the 6,874 participants in the trial were overweight or obese and had metabolic syndrome—high blood pressure, high blood sugar, altered cholesterol, and excess fat around the waist.
The new study, published Wednesday in the journal JAMA Network Open, examined one- and three-year results in a subpopulation of 1,521 people who underwent scans to determine levels of visceral abdominal fat.
Half of the group was asked to follow a Mediterranean diet with a 30 percent reduction in calories and limit the intake of added sugar, biscuits, refined breads and cereals, butter, cream, processed meats, and sweetened drinks. In addition, the intervention group received help from trained dietitians three times a month during the first year, along with training on how to self-monitor and set goals.
That same group was also asked to increase their aerobic exercise over time to walking 45 or more minutes a day along with exercises to improve strength, flexibility, and balance, all of which are critical to aging well.
“When you cut calories, you lose both lean and fat mass. When you add exercise, it helps to protect lean mass, especially if you add resistance training to build muscle. Generally, the ideal is to lose fat, retain muscle,” said Dr. Katz, who led published research on how to use food as preventive medicine.
The remaining participants were given general advice during group sessions twice a year and served as the control group for the study.
“It would have been much more informative had the control group received a similar high-intention support (even if it only contained generic advice),” said Gunter Kuhnle, a professor of food and nutritional science at the University of Reading in the United Kingdom, who was not involved with the study.
“Motivation and compliance is very important in studies that investigate behaviour change, and the study design clearly favoured the intervention,” Mr. Kuhnle said in an email.
Modest, but Significant Findings
At the end of one year, people in the intervention group who followed the lower-calorie Mediterranean diet and exercised lost a modest amount of body fat during the first year, but it was significantly more than the control group. However, the intervention group did gain some of the fat back in years two and three as dietary advice and support was removed. The smaller amount of body fat lost by the control group remained stable over the three years.
However, “only participants from the intervention group decreased grams of visceral fat mass,” while visceral fat mass remained unchanged in the control group, according to the study.
Both groups did gain some lean muscle mass, but the intervention group did have a “more favorable body composition” in that they lost more fat than muscle, the authors said.
“What is most profound to me is the 3-year follow-up,” said Dr. Christopher Gardner, a research professor of medicine at the Stanford Prevention Research Center in California who directs its Nutrition Studies Research Group. He was not involved in the study.
“We rarely have studies to cite that were anything longer than a year,” Dr. Gardner said in an email. “The magnitude of the 3-year differences are modest, and the trend from 1-year to 3-year suggests that at 6-years the effects may be diminished to insignificance.” Still, he added, “3-year statistically significant differences are impressive!”
Mediterranean Diet
Studies have found the award-winning Mediterranean diet can reduce the risk for diabetes, high cholesterol, dementia, memory loss, depression, and breast cancer. The diet, which is more of an eating style than a restricted diet, has also been linked to stronger bones, a healthier heart, and longer life.
The diet features simple, plant-based cooking, with the majority of each meal focused on fruits and vegetables, whole grains, beans, and seeds, with a few nuts and a heavy emphasis on extra-virgin olive oil. Fats other than olive oil, such as butter, are consumed rarely, if at all, and sugar and refined foods are reserved for special occasions.
Red meat is used sparingly, usually only to flavor a dish. Eating healthy, oily fish, which are packed with omega-3 fatty acids, is encouraged, while eggs, dairy, and poultry are eaten in much smaller portions than in the traditional Western diet.
Social interactions during meals and exercise are basic cornerstones of the Mediterranean style of eating. Lifestyle changes that are part of the diet include eating with friends and family, socializing over meals, mindfully eating favorite foods, as well as mindful movement and exercise.
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