Low-, high-intensity workouts appear to reduce waist circumference

Patients at risk for diabetes or heart disease may want to choose their workout intensity based on health goals, according to a study.

Researchers studied 300 sedentary, abdominally obese adults without diabetes to determine the separate effects of exercise amount and intensity on abdominal obesity and glucose tolerance. Participants were randomly assigned to perform short, high-intensity workouts or long, lower-intensity workouts 5 times a week for 24 weeks. The control group of 75 patients did not exercise.

Intervention patients underwent 5 weekly sessions of low-amount, low-intensity (LALI) exercise; high-amount, low-intensity (HALI) exercise; or high-amount, high-intensity (HAHI) exercise. All participants were instructed to eat a healthy diet but did not reduce their caloric intake. Study results appeared in the March 3 Annals of Internal Medicine.

After 24 weeks, all 3 exercise groups experienced similar reductions in waist circumference (P>0.43). Compared to the control group, reductions in waist circumference greater in the exercise groups: LALI group (−3.9 cm; 95% CI, −5.6 to −2.3 cm; P<0.001), HALI group (−4.6 cm; 95% CI, −6.2 to −3.0 cm; P<0.001), and HAHI group (−4.6 cm; 95% CI, −6.3 to −2.9 cm; P<0.001).

Only participants in the high-intensity exercise group experienced reduction in 2-hour glucose levels (−12.5 mg/dL; 95% CI, −23.5 to −1.5 mg/dL; P=0.027). There was no difference for the LALI or HALI group versus the control group (P>0.159).

The researchers noted that the findings support consensus recommendations that exercise is associated with about a 4.5-cm reduction in waist circumference, independent of its intensity. The reduction in waist circumference is the same when the same amount of energy is expended by exercising for 300 minutes per week at moderate intensity (routine walking at 50% intensity) or 200 minutes per week at vigorous intensity (brisk walking or light jogging at 75% intensity).

The authors wrote, “Combined with the observation that a 5-cm reduction in WC [waist circumference] is associated with a 9% lower risk for death in healthy middle-aged adults, our findings are encouraging and provide treatment options for clinicians who seek lifestyle-based strategies for reducing abdominal obesity in adults at increased health risk.”