The South Pacific archipelago of Vanuatu, like many developing countries, is currently experiencing a shift in disease burdens from infectious to chronic diseases with economic development. A rapid increase in obesity prevalence represents one component of this “health transition.” We sought to identify behaviors associated with measures of obesity in Vanuatu. We surveyed 534 adults from three islands varying in level of economic development. We measured height; weight; waist and hip circumferences; triceps, subscapular and suprailiac skinfolds; and percent body fat (?) by bioelectrical impedance. We assessed diet through 24-hour dietary recall and physical activity patterns using a survey. We calculated prevalence of obesity and central obesity based on multiple indicators (body mass index, ?, waist circumference, and waist-to-height ratio), and analyzed differences among islands and associations with behavioral patterns. Obesity prevalence was lowest among rural and highest among suburban participants. Prevalence of central obesity was particularly high among women (up to 73.9%), even in rural areas (ranging from 14.7% to 41.2% depending on the measure used). Heavier reliance on animal protein and incorporation of Western foods in the diet – specifically, tinned fish and instant noodles – was significantly associated with increased obesity risk. Even in rural areas where diets and lifestyles remain largely traditional, modest incorporation of Western foods in the diet can contribute to increased risk of obesity. Early prevention efforts are thus particularly important during health transition. Where public health resources are limited, education about dietary change could be the best target for prevention.