Among overweight adults or adults with obesity, weight loss through lifestyle changes may be associated with beneficial effects on heart rate variability (HRV), according to a study in Clinical Nutrition.
Researchers conducted a systematic review to determine whether weight loss through lifestyle changes affects sympathetic tone in overweight and obese patients and to evaluate the impact of weight loss on HRV.
The investigators searched for original studies published between January 1, 2000, and November 16, 2021, in the electronic bibliographic MEDLINE, Embase, EBSCO host, and VHL REGIONAL/LILACS databases. Eligible studies included controlled, randomized, parallel, or crossover trials; studies that assessed physical activity and/or dietary intervention for weight loss; studies with adults aged 18 years or older with overweight or obesity defined according to local standards for body mass index (BMI); and studies that evaluated HRV and body weight. The main outcome was changes in HRV parameters.
A total of 12 studies were included, 6 randomized clinical trials and 6 nonrandomized clinical trials. The population sizes ranged from 6 to 285 participants, with a mean BMI of 27.9 to 45.4 and mean age of 29 to 62.3 years. The intervention was diet alone in 9 studies, diet and exercise in 2 studies, and diet vs diet and exercise in 1 study. The intervention time ranged from 11 days to 8 months.
…this review demonstrates the beneficial ability of dietary intervention and physical activity to improve HRV parameters and increase parasympathetic activity in overweight or obese individuals.
In 3 studies, weight loss ranged from 5% to 10%, and 4 studies resulted in weight loss of more than 10%. A significant increase in RR interval (iRR) occurred in 4 studies and 6 studies showed a significant decrease in heart rate after weight loss. In 1 study, a decrease in HR was found in the group that underwent caloric restriction and exercise. The overall median increase in iRR was 5.7%, and participants with the largest increase in iRR above the median had a greater decrease in weight.
Regarding frequency-domain HRV variables, low frequency (LF) power was assessed in 4 studies, with 2 showing no difference postintervention (1 night-time evaluation) and 2 demonstrating a significant increase in LF. In addition, high frequency (HF) was evaluated in 4 studies, with 2 studies resulting in a significant increase and 2 finding no difference. LF/HF ratio was assessed in 8 studies, with 5 showing a significant reduction after weight loss.
Leptin was evaluated in 4 studies, 3 of which resulted in a significant decrease after weight loss. Adiponectin was assessed in 4 studies, 3 of which showed a significant reduction after weight loss.
Among several limitations, the review is based on only 12 studies, with a high degree of heterogeneity in the variables …….