Background: serotonin signaling participates in body weight regulation and glucose metabolism. However, little information is available on circulating serotonin levels in obese subjects after a weight loss program. We aimed to assess the effect of a lifestyle intervention on serotonin levels in obese children and possible associations with anthropometric and blood glucose measurements.
Methods: forty-four obese children were enrolled in a ten-week lifestyle intervention consisting of a moderate caloric restriction diet, nutritional education and familial involvement. They were distributed according to the weight loss response. Subjects who lost > 0.5 BMI-SDS were considered as high responders (HR; n = 22) and those who lost 0.5 BMI-SDS, as low responders (LR; n = 22). Anthropometric, biochemical parameters and plasma serotonin levels were measured as pre and post-intervention values.
Results: obese children (HR and LR groups) were able to reduce anthropometric indices and to improve glucose profile after the intervention. Interestingly, plasma serotonin levels were significantly (p < 0.05) reduced in all subjects (-35.14 nmol/I HR group and -30.63 nmol/I LR group). Moreover, multiple-adjusted regression models showed a significant association between pre-intervention (R-2 = 0.224, B = 0.047; p = 0.004) and post-intervention (R-2 = 0.140; B = 0.055; p = 0.042) plasma serotonin and glucose levels. In addition, in HR subjects changes in plasma serotonin were associated with changes in glucose levels (R-2 = 0.292; b = 0.04; p = 0.045). Interestingly, pre and post-intervention plasma serotonin levels were inversely associated (p < 0.05) with anthropometric measures.
Conclusions: serotonin levels were reduced after a lifestyle intervention independently of the program response. Moreover, plasma serotonin levels were associated with glucose and anthropometric measures in obese children.