Is Your Gut Microbiome Making You Fat?

What you eat feeds your gut bacteria, and your gut bacteria help decide how efficiently you burn or store energy. Three microbial markers stand out in the research on weight and metabolism: the balance of Firmicutes to Bacteroidetes, levels of Akkermansia muciniphila, and the production of short chain fatty acids (SFCA), specifically, butyrate.

The encouraging news is that all three respond to diet, often within weeks. Below is a practical guide to the foods that support each one.

Rebalancing the Firmicutes to Bacteroidetes ratio

A higher ratio of Firmicutes to Bacteroidetes has been linked to increased calorie extraction and potential weight gain. Landmark studies found that an obesity-associated microbiome harvested more energy from the same food (Ley et al., 2006; Turnbaugh et al., 2006).

Later human studies have been less consistent, so the ratio is best viewed as one piece of a bigger picture rather than a stand-alone marker (Magne et al., 2020). Even so, the dietary patterns that shift it are the same ones that support overall gut health.

Food or habit	Examples	How it helps
Fibre-rich whole plant foods	Vegetables, legumes, whole grains	Fibre feeds Bacteroidetes and other beneficial species
Legumes and pulses	Lentils, chickpeas, black beans	Provide fermentable fibre and resistant starch
Polyphenol-rich foods	Green tea, berries, cacao, extra virgin olive oil	Polyphenols act as prebiotics and shift microbial balance
Fermented foods	Kefir, unsweetened yoghurt, sauerkraut, kimchi	Increase microbial diversity and lower inflammatory markers (Wastyk et al., 2021)
Fewer refined sugars and ultra-processed foods	Swap pastries for oats, soft drinks for sparkling water	Western-style diets favour Firmicutes dominance

Supporting Akkermansia muciniphila

Akkermansia muciniphila lives in the mucus layer of the gut lining. Higher levels are associated with lower body fat, better blood sugar control and a stronger gut barrier (Everard et al., 2013). One of its proteins stimulates GLP-1, the hormone that signals fullness and steadies blood glucose (Yoon et al., 2021). In a human pilot trial, Akkermansia supplementation improved insulin sensitivity and reduced cholesterol in overweight adults (Depommier et al., 2019).

Akkermansia thrives on polyphenols and prebiotic fibres.

Food	Examples	How it helps
Red and purple polyphenol foods	Pomegranate, cranberries, red grapes, blueberries	Polyphenols markedly increased Akkermansia in animal studies (Anhê et al., 2015; Roopchand et al., 2015)
Inulin-rich vegetables	Leek, onion, garlic, Jerusalem artichoke, chicory root	Inulin-type fructans fuel Akkermansia growth
Green tea	Matcha, sencha	Catechins support Akkermansia and gut barrier integrity
Omega-3 fats	Sardines, salmon, mackerel	Fish oil favoured Akkermansia over saturated fat in animal research (Caesar et al., 2015)
Apples with skin	Granny Smith and other varieties	Combine pectin fibre with polyphenols

Boosting butyrate production for fat reduction

Butyrate is a short-chain fatty acid made when beneficial bacteria ferment fibre. It fuels the cells lining the colon, calms inflammation and improves insulin sensitivity (Gao et al., 2009). People with type 2 diabetes show fewer butyrate-producing bacteria (Qin et al., 2012), and a high-fibre diet that boosted these species improved blood sugar control (Zhao et al., 2018).

Food	Examples	How it helps
Resistant starch	Cooked and cooled potatoes or rice, green bananas, green banana flour	Escapes digestion and is fermented into butyrate (Venkataraman et al., 2016)
Beta-glucan grains	Rolled oats, barley	Fermentable fibre that feeds butyrate producers
Legumes	Lentils, chickpeas, cannellini beans	Combine resistant starch and fibre
Inulin and FOS foods	Garlic, onion, asparagus, chicory	Feed bifidobacteria, which cross-feed butyrate producers
Seeds	Ground flaxseed, chia	Soluble fibre and mucilage for fermentation
Butter and ghee (small amounts)	Grass-fed butter	Contain a modest amount of butyrate directly

Putting it together on your plate

You will notice the same foods appearing across all three tables: legumes, onions, garlic, oats, berries and green tea. That overlap is good news. A colourful, fibre-rich plate supports all three markers at once.

A few practical tips:

• Increase fibre gradually over two to three weeks to minimise bloating.

• Aim for 30 different plant foods each week, including herbs, nuts and seeds.

• Drink plenty of water as fibre intake rises.

Every microbiome is different, so the same foods can produce different results from person to person. If you bloat when eating more of these foods, there may be some underlying gut microbial imbalance that needs to be addressed more specifically.

Functional microbiome testing shows exactly where your gut stands, so your plan can be targeted rather than guesswork. If weight loss has felt like an uphill battle, it may be time to take a more holistic view and book in for a Comprehensive Gut Microbiome Test.

Book a free discovery call with me to explore what your gut is telling you.

In health and love

Deena

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References

1. Anhê FF, et al. A polyphenol-rich cranberry extract protects from diet-induced obesity, insulin resistance and intestinal inflammation in association with increased Akkermansia spp. population in the gut microbiota of mice. Gut. 2015;64(6):872–883.

2. Caesar R, et al. Crosstalk between gut microbiota and dietary lipids aggravates WAT inflammation through TLR signaling. Cell Metab. 2015;22(4):658–668.

3. Depommier C, et al. Supplementation with Akkermansia muciniphila in overweight and obese human volunteers: a proof-of-concept exploratory study. Nat Med. 2019;25(7):1096–1103.

4. Everard A, et al. Cross-talk between Akkermansia muciniphila and intestinal epithelium controls diet-induced obesity. PNAS. 2013;110(22):9066–9071.

5. Gao Z, et al. Butyrate improves insulin sensitivity and increases energy expenditure in mice. Diabetes. 2009;58(7):1509–1517.

6. Ley RE, et al. Microbial ecology: human gut microbes associated with obesity. Nature. 2006;444(7122):1022–1023.

7. Magne F, et al. The Firmicutes/Bacteroidetes ratio: a relevant marker of gut dysbiosis in obese patients? Nutrients. 2020;12(5):1474.

8. Qin J, et al. A metagenome-wide association study of gut microbiota in type 2 diabetes. Nature. 2012;490(7418):55–60.

9. Roopchand DE, et al. Dietary polyphenols promote growth of the gut bacterium Akkermansia muciniphila and attenuate high-fat diet-induced metabolic syndrome. Diabetes. 2015;64(8):2847–2858.

10. Turnbaugh PJ, et al. An obesity-associated gut microbiome with increased capacity for energy harvest. Nature. 2006;444(7122):1027–1031.

11. Venkataraman A, et al. Variable responses of human microbiomes to dietary supplementation with resistant starch. Microbiome. 2016;4(1):33.

12. Wastyk HC, et al. Gut-microbiota-targeted diets modulate human immune status. Cell. 2021;184(16):4137–4153.

13. Yoon HS, et al. Akkermansia muciniphila secretes a glucagon-like peptide-1-inducing protein that improves glucose homeostasis and ameliorates metabolic disease in mice. Nat Microbiol. 2021;6(5):563–573.

14. Zhao L, et al. Gut bacteria selectively promoted by dietary fibers alleviate type 2 diabetes. Science. 2018;359(6380):1151–1156.