A lower-calorie Mediterranean diet, combined with regular exercise, helped older women lose weight without causing bone density loss, new research suggests.
Weight loss, especially quick or significant weight loss, is known to reduce bone mineral density and increase risk of fracture. Older women are more prone to bone loss due to drops in estrogen during menopause.
Of the 10 million Americans with osteoporosis — a “silent” disease that weakens bones and rarely causes symptoms — more than 80% are women, a quarter of whom are aged 65 or older, according to the Food and Drug Administration's Office of Women’s Health.
Lifestyle changes, however, could offset those negative effects by preventing muscle loss, which plays a major role in overall bone strength, said Jesús García Gavilán, co-first author of the study and biostatistician at the University of Rovira I Virgili in Spain.
The research, published in the journal JAMA Network Open, builds on a 2023 study that found a similar low-calorie diet and exercise regime lowered total body and visceral fat (fat that surrounds organs) in the same study group.
In the new research, 924 Spanish adults ages 55–75 who are overweight or have obesity, and have metabolic syndrome — a cluster of conditions like high blood pressure, high cholesterol, and high blood sugar — were separated into two groups.
One group followed a Mediterranean diet with a 30% calorie reduction and gradually increased their physical activity to meet international recommendations for their age group.
The exercise routine consisted of:
- 45-minute walks, six days a week.
- Strength, flexibility and balance exercises three days per week.
- 30- to 40-minute resistance training sessions two days per week.
People in the control group followed a Mediterranean diet with no restrictions or exercise recommendations.
A Mediterranean diet consists mostly of plant-based foods, fish and healthy fats like olive oil.
Each participant had their own daily calorie intake based on their weight, height and sex, Gavilan said. They reduced their calories by cutting down on meats and sausages, sugars, white bread, packaged fruit juices and sugary drinks.
All participants received special X-rays that measured their bone mineral density in their femur and lumbar spine at the start of the study and then a follow-up after three years.
Overall, bone density improved the most in the lumbar spine among those in the lower-calorie diet and exercise group, Gavilán said. Women received the most benefits with a 1.8% improvement in lumbar spine bone density.
Dr. Dolores Shoback, an endocrinologist with UCSF Health who was not involved in the study, called this a “very modest effect” compared to improvements you see with drugs used to treat osteoporosis. Studies have found increases in bone density in the lumbar spine anywhere from 3–13% after a year of treatment with these medications.
She said this is likely because the study participants didn’t have a lot of bone loss from the start, and they also didn’t lose that much weight. People in the intervention group lost 3% of their total body weight over three years, which equals to about three pounds on average, Gavilán said.
Still, experts say the study sheds light on the crucial roles diet and exercise play in mitigating the effects that rapid weight loss has on bone health— a phenomenon more people are experiencing with the use of weight loss drugs.
How weight loss affects bone health
The risk of bone loss increases when a person drops a lot of weight in a short period of time, said Dr. Kristi Tough DeSapri, an internal medicine physician and osteoporosis expert with the Bone Health & Osteoporosis Foundation. Quick weight loss means there's less resistance on the bone as someone loses muscle along with fat, said DeSapri, who was not involved in the study.
Risk for bone loss depends on many factors, such as age, body weight, physical activity levels and diet. Hormonal changes associated with weight loss, as well as a lack of calcium and vitamin D in calorie-restricted diets, can also contribute to bone loss, research shows.
A 10% weight loss can result in a 1% to 2% bone loss in different areas of the body, research indicates. The bone loss numbers may double or triple in people who undergo bariatric surgery or use weight loss drugs such as semaglutide, the active ingredient in Novo Nordisk’s Ozempic and Wegovy, DeSapri said.
A study published last year found that people who used GLP-1 medications without exercising experienced a significant decrease in bone density in their hip and spine; when exercise was added to the mix, bone mass was protected.
Shoback said the exercise regime in the new study may “be a big commitment every day” for older adults to realistically follow, but it could be valuable for younger adults who are at high risk for metabolic syndrome and may experience rapid weight loss with medications.
Although the study was conducted in Spain, experts say the diet and exercise plan could benefit adults in the U.S.
In the United States, there’s a big push now for protein and supplements, DeSapri said.
“But when we’re talking about obesity, metabolic syndrome and weight loss, the Mediterranean diet has already been validated as a lifestyle that can make a difference,” she said.
The U.S. Preventive Services Task Force, an independent group of experts who recommend health screenings, says that women 65 years and older should receive a bone density scan for osteoporosis.
Osteoporosis risk can be lowered by staying physically active, not smoking, limiting alcohol use and getting enough vitamin D and calcium in the diet via milk and salmon, or supplements, Shoback said.
Hormone therapy is another effective way to reduce bone loss after menopause.
“Lifestyle combined with a heart healthy diet — if people can do that, that’s going to help them a lot for so many of the complications that come your way as we age,” Shoback said.