Older adults who eliminated 250 calories a day — about the same amount found in a 20-ounce soda or a candy bar — and paired it with moderate exercise had greater improvement in aortic stiffness, a prognostic marker for cardiovascular risk, compared with people who only exercised or who exercised and cut more than twice as many calories, according to research published on August 2 in the journal Circulation.
“This study provides evidence that for older adults who are obese, combining aerobic exercise with a moderate decrease in daily calorie intake may help to reduce aortic stiffness,” says Tina E. Brinkley, PhD, 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 School of Medicine in Winston Salem, North Carolina.
“Although the time and effort it takes to add exercise and make changes to your diet can be challenging, our findings suggest that these changes could reap some significant benefits for heart health,” says Dr. Brinkley.
Arteries Get Stiffer With Age
According to the authors, existing research suggests that obesity may speed up age-related increases in aortic stiffness, and so the study was designed to investigate whether exercise alone or with moderate to high calorie restriction could lead to improvements.
Aortic stiffness is exactly what it sounds like, and is part of normal aging or disease, says Brinkley. “It’s when the aorta, which is the largest artery in your body, becomes stiff. When your heart pumps, it contracts and pumps blood out of the heart through the aorta, which is responsible for distributing that blood throughout the body,” she says.
In a healthy elastic aorta, the vessel is able to expand during the contraction, and then slowly recoil back to its original dimensions to provide a steady flow of blood throughout the body, she explains. “When the aorta is stiff, it’s really no longer a steady flow but instead more of a ‘pulsing’ flow which can be very damaging to key organs such as the brain, the kidneys, and even the heart itself,” says Brinkley.
The randomized, controlled trial included 160 sedentary adults ages 65 to 79 years with obesity, which was defined as a body mass index (BMI) between 30 and 45. The average age of the participants was 69 years old; 74 percent were female, and 73 percent were white.
Participants were randomly assigned to one of three intervention groups for 20 weeks: 1) exercise only with their regular diet; 2) exercise plus moderate calorie restriction (reduction of approximately 250 calories per day); or 3) exercise plus more intensive calorie restriction (reduction of approximately 600 calories per day). Everyone in the study received supervised aerobic exercise training four days per week for 30-minutes a session at a moderate-to-vigorous intensity.
The structure and function of the aorta were assessed with cardiovascular magnetic resonance imaging.
The groups that combined diet and exercise shed nearly 10 percent of their total body weight or about 20 pounds over the five-month study period. An association with significant improvements in aortic stiffness was only found in the participants assigned to the exercise plus moderate calorie restriction group — not the intensive calorie restriction group or in the exercise only group.
Other key findings included:
- Changes in BMI, total fat mass, percent body fat, abdominal fat, and waist circumference were greater in both of the calorie-restricted groups compared with the exercise-only group.
- Weight loss was similar between the calorie-restricted groups despite nearly 2 times fewer calories in the intensive calorie restriction group.
“It makes sense that the addition of exercise to calorie restriction was the more causal factor with respect to reduction in vascular stiffness,” says Tamanna Singh, MD, co-director of the Sports Cardiology Center at Cleveland Clinic in Ohio. Dr. Singh was not involved in this research.
Earlier studies have found that aerobic exercise improves artery stiffness even after just a few weeks of training with exercise-mediated adaptations including reductions in wall stress, oxidative stress, and inflammation, she says.
“It’s interesting that a higher level of calorie restriction resulted in about the same level of weight loss as moderate calorie restriction, yet the moderate calorie restriction group ended up with less aortic stiffness,” says Tracy Wang, MD, professor of medicine in cardiology at Duke University School of Medicine in Durham, North Carolina, and American Heart Association volunteer expert, who was not involved in this research.
In other studies, losing weight has shown vascular benefit too, in part because the weight loss results in metabolic improvements that lower demand on the heart, reduces blood pressure, and changes the hormonal environment that “de-stresses” the aorta, explains Dr. Wang.
Given the similar amounts of weight loss, one would expect that the higher calorie restriction would have seen the same effect, but some studies have shown that prolonged fasting increases stress hormone levels, which can lead to the acceleration of atherosclerosis, or hardening of the arteries, she says. “It’s possibly that an overly restrictive diet resulted in a ‘starvation’ state, that counteracted the benefits of weight loss,” says Wang.
Small but Consistent Changes Can Make Big Differences in Health
“This study reinforces the idea that for patients dealing with obesity, exercise and caloric restriction not only serve short-term weight loss goals but may lead to long-term cardiovascular health improvement,” says Wang.
More drastic changes in cutting calories doesn’t seem to offer additional benefit compared with moderate restriction, and that type of severe restriction tends not to be maintainable, she says. “It’s the long haul that matters,” adds Wang.
“I think a key takeaway is that exercise plays an incredible role in improving vascular health,” says Singh.
It’s also important to pay attention to the quality of your calories, she says. A plant-based diet that focuses on whole foods is best for vascular health; foods that are highly processed and contain unhealthy fats are pro-inflammatory and have the opposite effect, says Singh.