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Microbiome and obesity: how bacteria affect body weight
Why can two people with the same diet and level of physical activity have radically different weights? Part of the answer lies in the invisible inhabitants of our gut—the microbiome. New research suggests that the state of our microbiome may be a key factor in the development of obesity, influencing metabolism, appetite, and even the effectiveness of diets.
The microbiome is not just a passive collection of bacteria. It is a complex ecosystem that interacts with our immune, endocrine, and nervous systems every day. Disruption of this interaction can trigger metabolic disorders that lead to weight gain.
What is the microbiome and what role does it play?
Microbiome — is the totality of all microorganisms that inhabit the human body, in particular the intestine. The main role is played by:
bacteria (Bacteroidetes, Firmicutes, Lactobacillus, Bifidobacterium)
viruses, archaea and fungi — less studied, but also significant
The microbiome is involved in:
fiber fermentation
synthesis of short-chain fatty acids (SCFA)
modulation of immune response
regulation of appetite hormones (ghrelin, leptin)
nutrient absorption
protection against inflammation
How the microbiome is linked to obesity
Obese people often have reduced diversity of intestinal microflora. The balance of the main bacterial groups is also changing:
– the number of Bacteroidetes decreases
– the proportion of Firmicutes increases
– the level of bacteria increases, which contributes to increased calorie extraction from food
Comparison table: microbiome in normal and obese individuals
| Parameter | Normal weight | Adiposity |
|---|---|---|
| Diversity of microflora | High | Low |
| Firmicutes/Bacteroidetes ratio | Balanced | Increased |
| SCFA products | Moderate | Excessive (contributes to fat storage) |
| Intestinal permeability | Low | Increased |
| Chronic inflammation | Missing | Latent |
| Insulin sensitivity | Saved | Reduced |
Mechanisms of the microbiome's influence on weight
Increased energy extraction from food
Some bacteria break down fiber into fatty acids, which are then absorbed by the body. This increases the total calorie content of even a “low-calorie” diet.Effect on appetite
The microbiome regulates the release of ghrelin (the hunger hormone) and leptin (the satiety hormone), and also affects the pleasure centers in the brain.Formation of insulin resistance
Disruption of the microflora contributes to chronic low-level inflammation, which reduces insulin sensitivity and stimulates fat deposition.Intestinal barrier function
Dysbiosis increases the permeability of the intestinal wall - lipopolysaccharides enter the blood, which trigger inflammatory cascades.
How to diagnose the state of the microbiome
Available methods include:
PCR analysis of feces — identifies the main genera of bacteria
metagenomic sequencing — in-depth analysis of all DNA organisms
dysbiosis tests — analysis of the ratio of beneficial and opportunistic flora
inflammatory markers (calprotectin, Zonulin)
These studies help identify imbalances that may affect weight.
How to improve your microbiome for weight management
High-fiber diet: vegetables, fruits, whole grains
Fermented foods: kefir, yogurt, kimchi, sauerkraut
Probiotics and prebiotics — as prescribed by a doctor
Limiting added sugar and trans fats
Physical activity — promotes the growth of beneficial bacteria
Sleep and stress management — sleep disorders affect the microflora
The microbiome is not just a trendy topic, but a fundamental component of metabolic health. Its state affects not only weight, but also inflammation levels, hormonal balance, and even mood. Studying your own microbiome can be the first step towards an individualized approach to fighting obesity, especially if standard diets don't work or the weight quickly returns after losing weight.
