Median, range and 95% confidence interval (CI) for median of age, anthropometric variables, soluble leptin receptor, serum leptin and lipid profile levels of 48 overweight (Body mass index (BMI) = 25.00-29.99 kg/m2) and obese (BMI > 30.00 kg/m2) Thai males and 166 overweight and obese Thai females, compared with 26 males and 81 females in a control group (BMI = 18.50-24.99 kg/m2), were determined. The study subjects were persons who turned up regularly for physical check-ups at the Out-patient Department, General Practice Section, Ratchawithi Hospital, Bangkok, aged between 18-60 years. Serum leptin,
triglyceride and low density lipoprotein cholesterol/high density lipoprotein cholesterol ratios (LDL-C/HDL-C ratio) were significantly higher in the overweight and obese males and females. Soluble leptin receptor and HDL-C were significantly lower in the overweight and obese males and females. Cholesterol and LDL-C were significantly higher in the overweight and obese females, but there was no significant difference in the overweight and obese males when compared with the control males. Low soluble leptin
receptor levels were found in 38.1% (8/21) of the overweight and obese males, while 31.5% (29/92) were
found in the overweight and obese females. Elevated leptin levels were found in 66.7% (32/48) and 89.8% (149/166) of the overweight and obese males and females, respectively. Both low soluble leptin receptor levels and elevated leptin levels were found in 9.5% (2/21) and 29.4% (27/92) of the overweight and obese males and females, respectively. A significant positive correlation was found between soluble leptin receptor and cholesterol, and between weight, BMI, waist, hip and HDL-C, with leptin. Serum soluble leptin receptor levels were significantly negatively correlated with leptin and BMI. The results can elucidate the causes and
consequences of obesity, and are expected to aid the provision of care for overweight and obese Thai people.

Keywords: Serum leptin receptor, leptin, BMI, lipid profiles, obesity