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Older adults with obesity who combine aerobic exercise with eating slightly fewer calories each day see greater improvements in blood vessel health than those who just exercise or who exercise and eat a more restrictive diet, new research finds.

The study found eating just 200 fewer calories per day while increasing physical activity could help offset age-related stiffening of the aorta, the largest artery in the body. Aortic stiffness is a measure of blood vessel health and a risk factor for cardiovascular events such as heart attacks and strokes.

The aorta, which brings oxygen and vital nutrients from the heart to other key organs, stiffens as people age. When it does, the heart has to work harder to contract and pump blood throughout the body. Chronic conditions such as high blood pressure, Type 2 diabetes and obesity can accelerate aging and cause the aorta to stiffen at a younger age. Higher body mass index, body weight, total body fat and abdominal fat, as well as a larger waist circumference, all are associated with increased aortic stiffness.

Previous research has shown aerobic exercise can improve aortic function, but that it may not be enough on its own to help older adults with obesity. The new study of 160 obese, sedentary adults, ages 65-79, looked at what would happen if aerobic exercise were combined with lowering the number of calories consumed each day – either by about 200 calories or by about 600 calories. The findings appeared Monday in the ÃÛÑ¿´«Ã½ journal .

"We were surprised to find that the group that reduced their calorie intake the most did not have any improvements in aortic stiffness, even though they had similar decreases in body weight and blood pressure as the participants with moderate calorie restriction," lead study author Tina Brinkley said in a news release. Brinkley is an associate professor of gerontology and geriatric medicine at the Sticht Center for Healthy Aging and Alzheimer's Prevention at Wake Forest School of Medicine in Winston-Salem, North Carolina.

Researchers found supervised aerobic exercise training four times a week, when combined with eating about 200 fewer calories per day, led to a loss of roughly 20 pounds, or 10% of total body weight, over a five-month period. This was associated with a 21% increase in the aorta's ability to expand and contract, also called distensibility. Researchers also found an 8% decrease in the speed at which blood travels through the aorta, known as aortic arch pulse wave velocity. Higher distensibility and lower pulse wave velocity values indicate less stiffness in the aorta.

Measures of aortic stiffness did not change significantly for the exercise-only group or for the group that reduced calories the most alongside exercise. Weight loss was similar for both groups that reduced calories, even though one group consumed nearly three times fewer calories per day. Both calorie-reduction groups achieved greater reductions in BMI, total fat mass, percent body fat, abdominal fat and waist circumference than the exercise-only group.

"These results suggest that combining exercise with modest calorie restriction – as opposed to more intensive calorie restriction or no calorie restriction – likely maximizes the benefits on vascular health, while also optimizing weight loss and improvements in body composition and body fat distribution," Brinkley said. "The finding that higher-intensity calorie restriction may not be necessary or advised has important implications for weight loss recommendations to improve cardiovascular disease risk in older adults with obesity."

Editor's note: This story was updated Aug. 2, 2021. The study found eating 200 fewer calories per day, not 250, and exercising may improve health health in older adults with obesity.

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