Richer gut bacteria

Published in: Nature 2013
People studied: 49

In 49 people, the variety of genes in their gut bacteria rose during a weight-loss diet in those who started low. No comparison group.

Checked against: PubMed 23985875
Published in: Nature 2013
Last checked: 30 October 2026

Key takeaway

This study followed 49 adults (38 with obesity and 11 with overweight) through a weight-loss diet and then a weight-stable phase, and read the genes of their gut bacteria. About 40% started with a less varied mix of gut bacteria, and they had more metabolic problems and mild, long-lasting inflammation. During the diet, the variety of gut bacterial genes rose in this group and their health measures improved, though inflammation improved less.

At a glance

Type of study: small diet study, no comparison group
People studied: 49
Main result: The variety of gut bacterial genes rose during the diet in people who started low.
Strength of evidence: Small or uncontrolled studies

What this study does not show

A small study with no comparison group, so it cannot show the diet alone caused the change. It does not show that a richer gut community leads to better health later on.

Results from studies in groups of people, mostly in diet and movement programmes. They cannot be promised to any one person. This information is educational and does not replace a consultation with a doctor.