Carbohydrate Restriction with or without Exercise Training Improves Blood Pressure and Insulin Sensitivity in Overweight Women.

Objective: The purpose of this study was to evaluate the effects of a 4-week low-carbohydrate diet (LC) with or without exercise training on cardiometabolic health-related profiles in overweight/obese women.

Methods: Fifty overweight/obese Chinese women (age: 22.2 ± 3.3 years, body mass index (BMI): 25.1 ± 3.1 kg·m) were randomized to either a LC control group (LC-CON, = 16), a LC and high-intensity interval training group (LC-HIIT, = 17), or a LC and moderate-intensity continuous training group (LC-MICT, = 17). All groups consumed LC for 4 weeks, while the LC-HIIT and LC-MICT groups followed an additional five sessions of HIIT (10 × 6 s cycling sprints and 9 s rest intervals, 2.5 min in total) or MICT (cycling continuously at 50-60% of peak oxygen uptake (VO) for 30 min) weekly. Blood pressure, fasting glucose, insulin sensitivity, and several metabolic or appetite regulating hormones were measured before and after intervention.

Results: Significant reductions in body weight (- ~2.5 kg, 0.001, = 0.772) and BMI (- ~1 unit, 0.001, = 0.782) were found in all groups. Systolic blood pressure was reduced by 5-6 mmHg ( < 0.001, = 0.370); fasting insulin, leptin, and ghrelin levels were also significantly decreased ( 0.05), while insulin sensitivity was improved. However, there were no significant changes in fasting glucose, glucagon, and gastric inhibitory peptide levels. Furthermore, no group differences were found among the three groups, suggesting that extra training (i.e., LC-HIIT and LC-MICT) failed to trigger additional effects on these cardiometabolic profiles.

Conclusions: The short-term carbohydrate restriction diet caused significant weight loss and improved blood pressure and insulin sensitivity in the overweight/obese women, although the combination with exercise training had no additional benefits on the examined cardiometabolic profiles. Moreover, the long-term safety and effectiveness of LC needs further study.