Objectives: This study examined the association between the serum leptin level and body mass index (BMI) and the effects of urbanization and polymorphisms of leptin (LEP) or leptin receptor (LEPR) genes on the leptin level in three Solomon Islands populations.

Methods: A Melanesian population living in a remote area (participants: 106 males and 106 females, ages: 18–74 years), a Melanesian population in an urban area (89 and 94, 18–79 years), and a Micronesian population who migrated to a peri-urban area in the 1960s (84 and 69, 18–71 years) were studied. Anthropometric and serum leptin measurements and genotyping for LEP G-2548A and LEPR K109R and Q223R were performed.

Results: The prevalence of obesity (BMI ≥ 30 kg/m2) was the highest in the Micronesian population (30.1%), followed by the urban (18.6%) and the rural (2.4%) Melanesian population. The serum leptin concentration was the highest in the urban Melanesian, followed by the Micronesian and the rural Melanesian populations (P < 0.05). Interestingly, the parameter coefficients of the leptin concentrations on the BMIs were nearly identical in the urban and rural Melanesians after adjusting for age and gender. The LEPR 223Q/Q genotype was associated with an increased leptin level only in the Micronesian population after adjusting for BMI (P = 0.0008 and 0.0016 referenced to the Q/R and the R/R types, respectively).

Conclusions: These observations suggest that the increase in obesity in the Micronesians had a genetic component while that in Melanesians might have been related with the urbanization. Am. J. Hum. Biol., 2011. © 2010 Wiley-Liss, Inc.