The authors of the paper, published in Circulation, found a link between greater vascular benefits and exercise with modest – rather than intense – calorie restriction (CR) in elderly individuals with obesity.
“The finding that higher-intensity calorie restriction may not be necessary or advised has important implications for weight loss recommendations,” noted Tina E. Brinkley, Ph.D., lead author of the study and associate professor of gerontology and geriatric medicine at the Sticht Center for Healthy Aging and Alzheimer’s Prevention at Wake Forest University in Winston-Salem, N.C.
It’s “not entirely clear” why greater calorie restriction did not translate to greater vascular benefit, but it “could be related in part to potentially adverse effects of severe CR on vascular function,” she noted. “These findings have important implications for reducing cardiovascular risk with nonpharmacological interventions in high-risk populations.”
Methods and findings
The study included 160 men and women aged 65-79 years, with a body mass index (BMI) of 30 to 45 kg/m2. The subjects were randomized to one of three groups for 20 weeks of aerobic exercise only, aerobic exercise plus moderate CR, or aerobic exercise plus more intensive CR. Their exercise regimen involved 30 minutes of supervised treadmill walking for 4 days per week at 65%-70% of heart rate reserve.
Subjects in the moderate CR group decreased caloric intake by 250 kcals a day, while the intense calorie reduction group cut 600 kcals per day. Their meals contained less than 30% of calories from fat and at least 0.8 g of protein per kg of ideal body weight. They were also provided with supplemental calcium (1,200 mg/day) and vitamin D (800 IU/day).
Cardiovascular magnetic resonance imaging was used to assess various aspects of aortic structure and function, including aortic arch pulse wave velocity, aortic distensibility and dimensions, and periaortic fat.
Weight loss was greater among subjects with CR plus exercise, compared with that of patients in the exercise-only group. The degree of weight loss was not significantly different between those with moderate versus intense CR ( 8.02 kg vs. 8.98 kg).
Among the exercise-only group, researchers observed no changes in aortic stiffness. However, adding moderate CR significantly improved this measure, while intense CR did not.
Specifically, subjects in the moderate-CR group had a “robust” 21% increase in distensibility in the descending aorta (DA), and an 8% decrease in aortic arch pulse wave velocity, whereas there were no significant vascular changes in the intense-CR group.
Bests results seen in exercise plus modest CR group
“Collectively, these data suggest that combining exercise with modest CR (as opposed to more intensive CR or no CR) provides the greatest benefit for proximal aortic stiffness, while also optimizing weight loss and improvements in body composition and body fat distribution,” noted the authors in their paper.
“Our data support the growing number of studies indicating that intentional weight loss can be safe for older adults with obesity and extend our previous findings, suggesting that obesity may blunt the beneficial effects of exercise for not only cardiorespiratory fitness, but likely vascular health as well.”
William E. Kraus, MD, professor in the Department of Medicine, Division of Cardiology at Duke University Medical Center, in Durham, NC, described the study as important and interesting for several reasons.
“First, it demonstrates one can change aortic vascular function with a combined diet and exercise program, even in older, obese Americans. This implies it is never too late to make meaningful lifestyle changes that will benefit cardiovascular health,” he said. “Second, it is among an increasing number of studies demonstrating that more is not always better than less in exercise and diet lifestyle changes - and in fact the converse is true.”
“This gives hope that more people can benefit from modest lifestyle changes - in this case following guidelines for physical activity and only a modest reduction of 250 kilocalories per day resulted in benefit,” Dr. Kraus added.
The authors of the paper and Dr. Kraus disclosed no conflicts of interest.