Exercise Without Cutting Calories? Good Luck With Vascular Aging

Caloric restriction and regular exercise worked in tandem to improve proximal aortic stiffness in older obese people, a small study showed.

These individuals showed some reversal in vascular aging — namely a 21% increase in descending aorta (DA) distensibility and 8% decrease in aortic arch pulse wave velocity on cardiac MRI — when they cut daily calories to 250 less than estimated daily energy needed for weight maintenance and underwent supervised treadmill exercise 4 days a week in comparison to exercise alone.

Improvements associated with moderate caloric restriction could be attributed in part to improvements in aortic strain, according to Tina Brinkley, PhD, of Wake Forest School of Medicine in Winston-Salem, North Carolina, and colleagues.

Exercise alone did not improve any of the studied cardiac MRI parameters, indicating that exercise without weight loss has no effect on proximal aortic stiffness in this population, they reported online in Circulation.

Notably, more intensive caloric restriction (i.e., limiting daily intake to 600 calories less than needed for weight maintenance) did not alleviate any of the aortic stiffness measures.

“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 in a press release.

“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,” she added.

Brinkley and colleagues also reported the surprising finding that adding moderate caloric restriction to an exercise program did not improve ascending aorta (AA) distensibility nor aortic strain in the AA. Neither AA nor DA dimensions changed with any kind of caloric restriction.

The literature suggests that in obesity, aortic stiffness begins distally and progresses upward to proximal segments if obesity is sustained, especially with advancing age.

“Altogether, these data may help explain why we observed more pronounced intervention effects on the DA versus AA, and specifically weight loss- versus exercise-induced improvements in proximal aortic stiffness, in this cohort of older adults with obesity,” Brinkley and colleagues reasoned.

Investigators performed an ancillary study of the INFINITE trial, which enrolled older, people with obesity who lived in or near Forsyth County, North Carolina. The 160 participants averaged age 69. Approximately three-quarters were women, and another three-quarters were white.

Participants were randomized to one of three groups: supervised aerobic exercise training only, exercise plus moderate caloric restriction, or exercise plus more intensive caloric restriction. Calories were controlled in the daily prepackaged lunches and dinners provided to people.

The three study arms had weight loss reach 3.66 lbs., 17.64 lbs., and 19.80 lbs., respectively, after 20 weeks of their assigned intervention.

Increases in aortic distensibility did not track weight and body fat loss upon statistical adjustment, according to Brinkley’s group.

The lack of a non-exercise control group was a major limitation of the study, as was the relatively short duration of the interventions.

“Future studies should determine the time course for changes in aortic structure and function after exercise- and diet-induced weight loss and how this translates to a reduction in cardiovascular morbidity and mortality,” the authors suggested.