How about a gut bacteria transplant!
• Research provides stronger evidence that the composition of gut bacteria influences obesity (Nature 2013;500:585).....fecal material from four human twin pairs (each set included one obese and one lean twin) was transplanted into genetically identical mice that were raised in a germ-free environment. The mice that received gut microbiota from obese humans became obese and developed obesity-related metabolism traits: dyslipidemia, insulin resistance, and inflammatory markers. In contrast, mice that received microbiota from lean humans stayed lean. Because mice routinely eat each other’s feces, researchers tried housing obese mice with lean mice — the obese mice gradually became lean and lost the obesity-related metabolic changes, and their gut flora changed to resemble that of the lean mice. The composition of gut bacteria involved just a few species.