Lower-calorie Mediterranean diet and exercise limit bone loss, even during weight loss, study finds

(CNN) — Older women who stayed on a reduced-calorie Mediterranean diet, walked and did resistance training for three years improved their bone density, especially in their lower backs, a new study found.

“A reduced-energy Mediterranean diet involves participants consuming a modified version of the traditional Mediterranean diet with approximately 30% fewer calories than their usual intake,” said coauthor Jesús Francisco García-Gavilán, a senior biostatistician at the University Rovira i Virgili in Tarragona, Spain.

Women in the study, who ranged in age from 55 to 75, were also able to prevent bone deterioration that typically occurs during weight loss, according to the research published Tuesday in the journal JAMA Network Open.

“Previous research has indicated that losing weight, particularly through diet alone, can lead to a reduction in bone density, which poses risks for older adults. Additionally, exercising alone does not always prevent this issue,” García-Gavilán said in an email.

“What is new in this study is the finding that combining a well-balanced, reduced-calorie Mediterranean diet with physical activity can prevent bone loss in older women, even while they are losing weight,” he said. “This emphasizes that the type of diet is important during weight loss, not just the calorie intake.”

The results of the study are not that surprising, said Dr. Andrew Freeman, director of cardiovascular prevention and wellness at National Jewish Health in Denver.

“When you practice the lifestyle that human beings were always meant to live, which is moving a lot and eating predominantly simple, plant-based foods, all sorts of systems get better, including bone density,” said Freeman, who was not involved in the new research.

Why the Mediterranean diet?

The new study is part of the PREDIMED-Plus trial, a randomized clinical trial on lifestyle interventions conducted in 23 medical centers and hospitals in Spain. The trial included 924 older adults with metabolic syndrome who were overweight or had obesity. Half were randomized to eating a Mediterranean diet with no restrictions on calories and no requirement to exercise.

The other half were encouraged to walk for a minimum of 45 minutes per day six days per week and to do strength, flexibility and balance exercises three days per week. Their diet was cut to about 30% fewer calories than they typically consumed and only from a Mediterranean-style eating plan. Women in this group saw significantly stronger bones at one year and at three years into the study.

“While previous results from the PREDIMED-Plus trial highlighted benefits for maintaining lean mass and losing weight, this is the first publication to demonstrate that these lifestyle changes can also help preserve bone density, especially in older women,” García-Gavilán said.

The award-winning Mediterranean diet features simple, plant-based cooking, with much 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 avoided.

Red meat is used sparingly, often 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.

Eating the Mediterranean way has been linked to reductions in the risk for breast cancer, dementia, depression, diabetes, high cholesterol and memory loss. Adherence to the diet can also lead to a healthier heart, weight loss and longer life.

But exactly why would the meal plan help preserve bone?

“The Mediterranean diet is rich in nutrients that promote bone health,” García-Gavilán said. “Nuts and dairy products provide essential calcium, magnesium, and vitamin D. Healthy fats, such as those found in olive oil, have been shown to reduce inflammation.”

Antioxidants such as vitamin C from fruits and vegetables may help protect and support bone cells, García-Gavilán added, while other important vitamins, like vitamin K found in vegetables such as spinach, play a role in bone formation.

“Together, these nutrients can lower the risk of bone loss and support bone maintenance, especially as we age,” García-Gavilán said. “Understanding this nutritional context is crucial for maintaining our long-term quality of life.”

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