How your gut bacteria can make you thin - or fat

  • It is quite established now that the bacteria that live in our gut - and which outnumber whole body human cells by 10 to 1 - are an integral "organ" of the human body
  • Lately it has been established that gut bacteria largely determine if a person is thin or overweight
  • In many instances, previously thin people turned overweight by fecal transplants from overweight people, and vice versa, overweight people lost weight by faecal transplants from thin people (fecal transplants are used in severe immune / infection problems, when all other methods have failed)
  • Furthermore, people who lose weight have a different bacterial population in their gut and vice versa
  • Now scientists are trying to determine which bacteria are more responsible for the thin / overweight body types, with the aim to boost the number of the former and reduce the number of the latter
  • Bacteria can alter body weight either by metabolising fibre (thereby providing us with extra calories from the food we already eat); by secreting substances that alter our metabolism or food, immune reaction to food, hormones/endocrine balance; by metabolising our own hormones which end up in the gut after processing by the liver; metabolising micronutrients that we ingest with our food etc.
  • Source: The gut microbiota in human energy homeostasis and obesity
  • Abstract: Numerous studies of rodents suggest that the gut microbiota populations are sensitive to genetic and environmental influences, and can produce or influence afferent signals that directly or indirectly impinge on energy homeostatic systems affecting both energy balance (weight gain or loss) and energy stores. Fecal transplants from obese and lean human, and from mouse donors to gnotobiotic mice, result in adoption of the donor somatotype by the formerly germ-free rodents. Thus, the microbiota is certainly implicated in the development of obesity, adiposity-related comorbidities, and the response to interventions designed to achieve sustained weight reduction in mice. More studies are needed to determine whether the microbiota plays a similarly potent role in human body-weight regulation and obesity.