The use of non-invasive brain stimulation techniques to reduce body weight and food cravings: a systematic review and meta-analysis

Several studies demonstrated non-invasive brain stimulation (NIBS) techniques such as transcranial direct current stimulation (tDCS) and transcranial magnetic stimulation (TMS) are safe and simple techniques that can reduce body weight, food cravings, and food consumption in patients with obesity. However, a systematic to evaluate the efficacy of active NIBS versus sham stimulation in reducing body weight and food cravings in patients with obesity is not available. We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) using PubMed, Embase, MEDLINE, and Cochrane Central Register of Control Trial between January 1990 and February 2022. Mean differences (MDs) for continuous outcome variables with 95% confidence intervals (95% CIs) were used to examine the effects of NIBS on body weight and body mass index (BMI), whereas the hedges's g test was used to measure the effects on food craving. Nineteen RCTs involving 571 participants were included in this study. Active neurostimulation (TMS and tDCS) was significantly more likely than sham stimulation to reduce body weight (TMS: -3.29 kg, 95% CI [-5.32, -1.26]; I  = 48%; p < .001; tDCS: -0.82 kg, 95% CI [-1.01, -0.62]; I  = 0.0%; p = .00) and BMI (TMS: -0.74, 95% CI [-1.17, -0.31]; I  = 0% p = .00; tDCS: MD = -0.55, 95% CI [-2.32, 1.21]; I  = 0% p = .54) as well as food cravings (TMS: g = -0.91, 95% CI [-1.68, -0.14]; I  = 88 p = .00; tDCS: g = -0.32, 95% CI [-0.62, -0.02]; p = .04). Compared with sham stimulation, our findings indicate that active NIBS can significantly help to reduce body weight and food cravings. Hence, these novel techniques may be used as primary or adjunct tools in treating patients with obesity.