Fermented Food and Weight Loss: Discover the Benefits for Your Health

Fermentation is one of the oldest food preservation techniques in the world, dating back centuries, long before refrigeration was even imaginable.

In recent years, fermented foods have surged in popularity, fueled by a wave of health claims, including their potential role in supporting weight loss.

In this article, we’ll explore what fermentation is, examine the science-backed benefits of fermented foods, and take a closer look at whether the weight loss claims truly stack up.

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What are Fermented Foods?

Fermentation is used in the production process of many of the food and drinks we enjoy on a regular basis, such as cheese and yoghurt.

The fermentation process is when bacteria, fungi or yeast convert sugars and starch into acids or alcohol, known as natural preservatives. This tends to leave the food with a strong salty or sour flavor.

Fermentation can either happen spontaneously when micro-organisms already present in the environment or the food kickstart the fermentation process (known as naturally fermented), or it can be done deliberately by using a 'starter culture'.

The latter is carefully selected bacteria or yeast (often lactic acid bacteria) that is deliberately introduced to encourage controlled fermentation.

Note that many spontaneous fermented foods can also be made using a starter culture. (1, 2)

Health Benefits of Fermented Foods

Fermented foods are generally a healthy choice, given that such foods generally contain little or no preservatives, flavorings or colorings; use unprocessed raw ingredients; and often use traditional technologies.

Certain fermented foods such as pickled vegetables and yoghurt may also be low in fat and calories (though certainly not all, as some contain added sugar or carbs).

Many high-quality reviews and clinical trials indicate that fermented foods (like yogurt, kimchi, kefir, miso, tempeh, etc.) are associated with improvements in metabolic markers, such as blood glucose levels, insulin sensitivity, cholesterol levels, body composition (and body fat), energy metabolism, and inflammation.

These effects are likely a beneficial result of changes in the gut microbiota, the trillions of microorganisms living in your GI tract, which can occur as a positive consequence of eating fermented foods. Along with the bioactive compounds they produce during fermentation.

Let's take a look at how fermented foods have the potential to influence your gut microbiome and, in turn, perhaps even reduce body weight...

1. Fermented Foods Can Support Your Gut Microbiota

While all fermented foods need microorganisms such as yeast and bacteria to create them, not all fermented foods will contain live microbes by the time it comes to eating them.

However, the ones that do may contain beneficial bacteria that may have a probiotic effect. These bacteria could help to support the balance of bacteria in the gut microbiome, potentially contributing to digestive health.

A healthy gut microbiome is essential for proper nutrient absorption, immune system function, and overall well-being. And, as it turns out, it has a significant knock-on effect on weight loss and weight gain.

Probiotics for Gut Health Benefits

Beneficial gut bacteria, such as those potentially found in fermented foods and fermented veggies, can have anti-inflammatory effects, improve gut health and may reduce the risk of irritable bowel syndrome and other health issues.

Now, I should point out that the microbes in fermented food aren't technically considered probiotic strains by the official definition - which states that they must confer a health benefit when eating.

But that's mostly because they haven't been specifically tested and named for that. However, it is widely recognized that they may have a probiotic effect. As such, many people describe them as probiotic bacteria anyway.

Limited studies have explored the impact of fermented vegetables and food on gut bacteria. Research is promising but more investigation is welcome.

STUDIES -

1. The American Gut Project investigated the gut microbiome profiles of 7,000 consumers and non-consumers of fermented food intake and noted a significant difference between the two.

"We found that fermented food consumers have subtle differences in their gut microbiota structure, which is enriched in conjugated linoleic acid, thought to be beneficial." (3)

2. A 2021 study compared the results of a high fermentation food diet with a high fiber diet over 17 weeks. The former resulted in a more diverse, healthier mix of gut bacteria compared to the fiber diet. (4)

3. Other clinical trials have examined the impact of specific fermented foods, such as fermented milk and yoghurt, noting a change in gut microbiota diversity after regular consumption.

"This review clearly shows that fermented foods can affect the gut microbiome in both the short and long term, and should be considered an important element of the human diet" - study authors. (5)

How can this influence weight loss?

The Link Between the Gut Microbiome and Weight Loss

It turns out that the gut or the GI tract is one of the most influential organs in the human body, influencing everything from our immune system, our brain, heart and other main organs, to our weight.

If our microbiome within the GI tract is off kilter or unbalanced, for instance, it can cause illness, low mood, digestive problems, chronic inflammation, and metabolic diseases - with a potential knock-on effect on weight gain.

Studies prove that our gut health and weight are linked, with the former playing a potentially significant role in weight loss.

"While we are aware there are several lifestyle factors that can contribute to failure, these results suggest that gut bacteria may also be a determinant of weight loss in response to diet and lifestyle changes," said the study author.

"More specifically, a gut microbiota with increased capability for carbohydrate metabolism appears to be associated with decreased weight loss." (7)

Probiotics and Weight Loss

A 2025 systematic review examined the role of prebiotics, probiotics and other interventions designed to alter or improve the gut microbiome among obese people. It reported that they resulted in 'significant reductions' in:

• Body fat percentage (less adipose tissue)

• Body weight

• BMI (Body Mass Index)

In addition, they improved inflammation, insulin sensitivity (reducing insulin resistance), metabolic health, and reduced cholesterol with minimal adverse effects. (8)

A 2015 study of people given a high fat diet gave one group probiotics and the control group a placebo. The first group ended up gaining 50% less body fat than the placebo group, demonstrating that probiotics may help reduce fat accumulation and reduce weight gain with the potential health benefits that brings. (9)

The science seems clear... boosting the beneficial microbes in your gut may help you reach and maintain a healthy weight. Fermented food and probiotic rich foods (or supplements) may be one way to do that.

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Here's how else fermented food may help...

2. May Help with Appetite Control

Leptin and ghrelin are two key hormones that control appetite - leptin helps you feel full, while ghrelin makes you feel hungry. Certain gut bacteria can influence how much of these hormones your body produces, which means your gut health plays a real role in shaping your appetite too.

When these hormones become unbalanced, it can be harder to regulate hunger, potentially leading to weight gain. This is why supporting a healthy gut microbiome - something we've already established fermented foods may help with - is beneficial.

Fermented vegetables are also high in fiber. When your 'good' gut bacteria breaks down fiber into Short Chain Fatty Acids (SCFAs), it can also trigger the release of other hormones that promote fullness, such as GLP-1 and PYY.

These hormones slow digestion and help your body use energy more efficiently. In several studies, people who consumed more prebiotic fiber, which feeds beneficial gut bacteria, showed higher levels of these fullness hormones and lower levels of hunger signals like ghrelin, although results can vary depending on the type and amount consumed. (11 - 13)

3. Potentially Reduces Inflammation

Eating more natural, minimally processed fermented foods has been shown in several studies to help lower markers of chronic inflammation in the body.

Because chronic inflammation is linked to insulin resistance and slower metabolism, reducing it through foods that nourish gut bacteria may help the body manage energy and weight more effectively. However, effects vary from person to person and most evidence comes from shorter-term studies. More research is welcome. (14, 15)

4. Influences Blood Lipids and Cholesterol

Many fermented foods such as yogurt, kefir, kimchi and sauerkraut are natural sources of beneficial bacteria such as Bifidobacterium and Lactobacillus (you'll find more live cultures in unpasteurized or raw versions). Certain strains have been shown to reduce total cholesterol and LDL, the 'bad' cholesterol.

Bifidobacterium, in particular, has been studied and tested in clinical trials on humans for its probiotic benefits. In one study of patients with metabolic syndrome, for instance, patients given Bifidobacterium demonstrated a reduction in blood lipids and inflammatory markers - and a reduction in body weight.

Other studies have shown that taking probiotics daily may help to reduce Body Mass Index (BMI), as well as LDL and total cholesterol compared to a control group. (16, 17)

In conclusion...

"Regular consumption of fermented foods can exert beneficial effects on body weight regulation and metabolic function through several mechanisms". (18)

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Other Health Benefits of Fermented Food

1. They are easier to digest, thanks to the fermentation process breaking down natural sugar and starches.

2. Compounds produced during fermentation can help regulate lipid metabolism and improve glucose control, as touched on above. (19)

3. Microbes in the fermentation process tend to remove toxins, as well as 'anti-nutrients' or natural compounds that can reduce absorption of other nutrients. In some cases, fermentation can even add beneficial nutrients and vitamins.

4. A healthy gut microbiome has wider benefits for overall health. The gut-brain axis has been shown to influence mood, while the gut-heart axis may protect against conditions such as coronary heart disease and hypertension or high blood pressure.

5. Finally, a whopping 70% of immune cells are located in the gut, meaning a healthy gut with diverse bacteria influences the immune system and our immune responses. (20 -24)

Is Fermented Food Safe?

Fermented foods are safe for the majority of people but if you're making your own, be sure to follow the recipe and instructions carefully. If you're new to a fiber-rich diet or a diet of fermented foods, you may experience symptoms such as flatulence and bloating.

Fermented foods tend to be high in histamine, so anyone with a histamine intolerance should beware. Certain fermented foods may also be high in salt and sugar.

How to add Fermented Foods to your Diet

You can make your own fermented foods at home using simple recipes and ingredients, making them a great addition to a healthy lifestyle. As I mentioned, just be sure to follow recipes and instructions carefully, especially temperature and timing.

You might want to start by choosing one or two products to try, beginning with small amounts and gradually increasing consumption as needed. Add into a healthy diet and lifestyle, including regular exercise and stress management.

Take Home Thoughts

Fermented foods aren’t a magic weight-loss solution, but the evidence suggests they may play a meaningful supporting role in overall metabolic health and a lower body weight.

By helping to nourish a more diverse and balanced gut microbiome, fermented foods may influence inflammation, appetite regulation, insulin sensitivity and how efficiently the body uses energy - all factors that matter when it comes to managing weight.

That said, individual responses vary, and most benefits appear when fermented foods are consumed regularly as part of a broader, healthy lifestyle rather than in isolation.

Think of them as one useful tool in the weight-management toolkit: best paired with a nutrient-dense diet, adequate fiber, movement, sleep and stress management, rather than a quick fix on their own.

Adding a quality probiotic supplement or a prebiotic like Performance Lab Prebiotic is another option, allowing you to gain your probiotics by just popping three pills a day.