Serotonin concentration between lean and obese groups. Data are presented as boxes and whiskers. Each box includes the interquartile range, whereas the line within a box represents the median, and the whiskers represent the range, extending to a maximum of 1.5 times the interquartile range. Serotonin levels were significantly lower in obese group compared with that of lean group. **p < 0.01: significant difference were observed between lean and obese groups.