You Lose Some, You Win Some: Weight Loss Induces Microbiota and Metabolite Shifts

Abstract

Obesity is an increasing problem worldwide. Nearly 30% of the world's population is overweight or obese, and this number is on the rise (Ng et al., 2014). Because high body-mass index is a strong risk factor for chronic conditions such as cardiovascular disease and diabetes, and is associated with increased mortality, the growing obesity rates are expected to have a significant impact on quality and expected length of life in the future (Prospective Studies Collaboration, 2009). Although obesity could simply be viewed as an imbalance between caloric intake and metabolism, work in the past decade has revealed an important role of the gut microbiota – the microbial communities present in our intestinal tract – in obesity as well (Turnbaugh et al., 2009). Gut microbes can extract calories from food that we humans cannot digest ourselves, and the composition of the gut microbiota from lean individuals has been shown to be distinct from that of obese persons (Ley, 2010). In addition, stool microbiota from human twin pairs discordant for obesity could transmit the obese phenotype to germ-free mice, suggesting that the gut microbiota plays an active role in obesity (Ridaura et al., 2013).