METS-Microbiome: Dietary Fiber, Gut Microbiota, and Obesity Risk Across the Epidemiologic Transition

Key Objectives

• Analyse the impact of declining dietary fiber intake on gut microbiota, circulating short-chain fatty acids (SCFAs), and obesity risk in diverse African-origin populations.

• Investigate the link between resting metabolic rate (RMR) and gut health, exploring how fiber intake and microbiota diversity affect energy expenditure and obesity risk.

• Conduct a controlled fiber supplementation trial to assess whether increased fiber intake can restore gut health, increase SCFA production, and improve RMR in low-fiber-consuming populations.

  
  

Scientific Rationale & Significance

• The epidemiologic transition—a shift from traditional to Westernized diets—has led to increased obesity and type 2 diabetes across developing nations.

• Gut microbiota diversity and SCFA levels are significantly associated with obesity risk and are strongly influenced by dietary fiber.

• New findings suggest that declining RMR, influenced by low-fiber diets and reduced SCFA production, is a major driver of obesity, particularly in the US compared to fiber-rich populations like Ghana.

• The hypothesis: Increasing dietary fiber intake can restore gut health and RMR, reducing obesity risk.

  
  

Study Design at a Glance

Sample Size: 

2,000 participants from five African-origin populations with detailed phenotype and dietary data

Approach:

• Assess fiber intake, microbiome composition, SCFA levels, and RMR

• Analyse cross-sectional and longitudinal associations

• Implement a 4-week fiber supplementation trial (70g/day) in 180 participants from Ghana, South Africa, and the US

Measurements:

• Gut microbiota sequencing

• Indirect calorimetry for RMR

• SCFA levels

• Biomarkers for glucose-insulin dynamics and gut peptides (e.g., GLP-1, PYY)

Expected Outcomes

• Clarify how dietary fiber, gut microbes, and energy metabolism interact to influence obesity risk.

• Identify potential microbiome-based interventions for metabolic health, especially in populations undergoing rapid dietary shifts.

• Establish evidence to support targeted nutritional strategies to combat obesity globally.