May 16, 2026

Weight Gain and Weight Loss: Does Your Body Weight Depend on Your Gut Microbiome?

5-minute read · Erzsébet Soltész, dietitian

Gut microbiome: a mysterious diversity

The human microbiome is one of the most popular research topics today, and tests to explore your individual gut microbiome are becoming available in more and more places. However, these tests are still essentially snapshots that can only show the most significant deviations in your current microbiome composition compared to what is considered optimal.

The number of microorganisms inhabiting our bodies and digestive systems is almost incomprehensible, somewhere in the order of 30,000,000,000,000 to 40,000,000,000,000. Several hundred types of bacteria live as permanent co-inhabitants in each of our digestive systems, and yet we still know relatively little about the complex processes and self-regulating mechanisms of this diverse inner world.

This is what makes research into the relationship between microbiome characteristics and various health conditions so exciting. Perhaps the most fascinating area is the connection to a tendency toward obesity and unintentional weight gain. What is the vicious cycle at play?

A global obesity epidemic: it's not just about calories

In films, the pandemic that escapes from a secret lab is always stopped at the last moment. In reality, however, humanity is losing the battle against obesity. There are already more than one billion people affected worldwide, and estimates suggest that by 2035, half the world's population will be overweight.

Fat deposits around the waist and a protruding belly are typical signs of visceral fat accumulating in the abdominal cavity, which is associated with an increased risk of metabolic syndrome, including type 2 diabetes, lipid metabolism disorders, non-alcoholic fatty liver disease, and cardiovascular conditions.

Alongside excessive calorie intake and insufficient physical activity, a fiber-poor diet associated with modern lifestyles is one of the main culprits in the obesity epidemic. Inadequate intake of the fibers that nourish the gut microbiome disrupts the balance of the digestive and metabolic systems, which can result in impaired sugar and fat metabolism.

Disruption of insulin regulation can sustain the vicious cycle of weight gain even without a caloric surplus. An important finding in recent years is that a tendency toward obesity and unsuccessful weight loss show a direct correlation with the composition of the gut microbiome. So which bacterial strains matter most?

Typical microbiome composition: cause and consequence

Several large-scale studies have observed characteristic differences in the gut microbiome composition of obese individuals. The ratio of the two most dominant bacterial phyla, Firmicutes and Bacteroidetes, was found to be elevated in obese subjects compared to those of normal body weight, meaning a "dominance" of Firmicutes was characteristic. This pattern is linked to diet: a diet high in fat and added sugar and low in fiber produces precisely this shift over the long term.

A higher proportion of Firmicutes is associated with more efficient energy extraction from food, which may contribute to a tendency toward obesity. In contrast, the Bacteroidetes phylum, and in particular certain members of the Bacteroides genus, are thought by scientists to have an anti-obesity effect. In mouse studies, Bacteroides therapy successfully reduced body weight and fat tissue in obese mice, a promising result for the development of targeted microbiome therapies against obesity.

The effect also worked in reverse: when the microbiome of obese mice was transplanted into normal-weight mice with sterile digestive systems, those mice also became obese, despite no change in their diet. This experiment further confirmed that microbiome composition has a direct effect on metabolism and the tendency to gain weight. But what is the right balance?

It's not that simple: the critical balance of the Firmicutes/Bacteroidetes ratio

Based on the above, Bacteroidetes bacteria might appear to be the good guys and Firmicutes the villains. According to numerous scientific publications, a shift in the Firmicutes/Bacteroidetes ratio in the gut microbiome is associated not only with obesity but also with disorders of fat and sugar metabolism, and even with a higher risk of breast cancer.

An obvious conclusion might be: "Let's get rid of all Firmicutes bacteria, and we can forget about dieting and prevent a whole range of diseases!" As tempting as this thought is, such an extreme approach would do no good.

As in every area of life, balance is what matters in the microbiome. It is a complex microbial world in which both bacterial phyla play important roles. They interact with each other through the substances they produce, and within BOTH groups there are bacteria that regulate our energy metabolism through their anti-inflammatory effects and their influence on appetite.

The Firmicutes/Bacteroidetes ratio can also be too extreme in the other direction: an EXCESSIVE presence of the otherwise "friendly" Bacteroidetes bacteria may be associated with a higher risk of irritable bowel syndrome and inflammatory bowel disease.

What is the takeaway? Instead of extreme diets, aim for variety and moderation in your eating habits. A balanced, nutrient and fiber-rich diet does the most to support your microbiome equilibrium. But how can you avoid being prone to weight gain in the first place?

How can you support your microbiome to avoid a tendency toward weight gain?

Fortunately, the gut microbiome is remarkably flexible: the composition of your diet can influence its makeup relatively quickly and significantly. To support beneficial, probiotic bacterial strains, it is worth regularly consuming fermented vegetables and live-culture dairy products.

The macronutrient composition of your diet also matters: excessive fat and sugar consumption damages the diversity of the microbiome and can promote the growth of certain disease-causing bacteria.

The most important task is ensuring adequate intake of the dietary fibers that feed your gut bacteria. The dietary fibers that pass through the digestive system in undigested form are gladly received by the residents of your microbiome. The fibers that serve as nutrients for these bacteria are called prebiotic fibers.

The best strategy for supporting the Bacteroidetes bacteria that offer some protection against a tendency to gain weight, and for restoring a healthy balance, is varied fiber consumption. Since your body cannot store fiber, you need to ensure you consume multiple types of fiber in your diet every day.

Wonderful examples of prebiotic fibers include:

Inulin, found in onions, Jerusalem artichokes, and artichokes
Pectin, found in apples, pears, and berries
Beta-glucan, found in oats and barley
Resistant starch, found in unripe or green bananas

How to take care of your microbiome:

The composition of your gut microbiome is critically important alongside diet and exercise for reaching and maintaining a healthy body weight.
To support a diverse gut microbiome, aim for the recommended daily intake of 30 grams of fiber.
Take care of your prebiotic fiber intake every day by eating a wide variety of vegetables, fruits, wholegrains, seeds, and nuts.
Make sure you consume multiple types of fiber each day and combine different fibers to make the most of their benefits.
If you are short on time and use a fiber supplement, check that it contains prebiotic fiber.
Alongside your fiber-conscious diet, drink plenty of plain water.

Sources used:

Soltész E., Gajda Z. Fiber is good! Budapest: BOOOK Publisher; 2020

An, J., Kwon, H., & Kim, Y. J. (2023). The Firmicutes/Bacteroidetes Ratio as a Risk Factor of Breast Cancer. Journal of clinical medicine, 12(6), 2216.

Barna, I., Nyúl, D., Szentes, T., and Schwab, R. (2018). A review of the relationship between the gut microbiome, metabolic diseases, and hypertension. Orvosi Hetilap OH 159, 9, 346-351.

NCD Risk Factor Collaboration (NCD-RisC). Worldwide trends in underweight and obesity from 1990 to 2022: a pooled analysis of 3663 population-representative studies with 222 million children, adolescents, and adults. Lancet. 2024;403(10431):1027-1050.

Ryu SW, Moon JC, Oh BS, et al. Anti-obesity activity of human gut microbiota Bacteroides stercoris KGMB02265. Arch Microbiol. 2023;206(1):19.

Turnbaugh PJ, Ridaura VK, Faith JJ, Rey FE, Knight R, Gordon JI. The effect of diet on the human gut microbiome: a metagenomic analysis in humanized gnotobiotic mice. Sci Transl Med. 2009;1(6):6ra14.

May 16, 2026

Fiber in the Kitchen: How to Cook and Bake with Fiber in Mind

5-minute read · Erzsébet Soltész, dietitian What kind of diet should you follow for adequate fiber intake? A microbiome-supporting, fiber-rich diet is the best strategy for maintaining good health. The good news is that it doesn't require anything special at the supermarket or in the kitchen. You don't need to follow a specific diet or avoid particular foods. The key is making sure that alongside the essential nutrients your body needs, the fibers that matter for your microbiome and digestive system are also present in your diet every day, in adequate amounts and from a variety of sources. To achieve this: Choose plant-based ingredients and foods that, in addition to their nutritional value, also provide a combination of prebiotic fibers to support your beneficial gut bacteria. Take care of your protein intake: alongside plant-based protein sources, you can eat meat, fish, eggs, and unsweetened dairy products according to your own preferences, in moderation. Be mindful with fats. In addition to the natural fat content found in nuts, seeds, eggs, dairy, and lean meats, regularly include quality olive oil and nut or seed oils in your diet. Avoid deep frying and ultra-processed foods that are loaded with sugar, salt, fat, and additives. Drink water when you're thirsty, and plenty of it alongside a fiber-rich diet. As straightforward as this list sounds, it can be equally frustrating to figure out how to actually put it into practice on busy weekdays. Why is it so hard to get started? The internet is full of an overwhelming number of great recipes featuring fiber-rich plant ingredients. The sheer abundance may actually be part of the problem: most people never end up making the recipes they save. The reasons can include deeply ingrained shopping habits, a lack of motivation, following family food traditions, or reluctance to try unfamiliar ingredients. Breaking a pattern of low-fiber eating that has built up over decades is not easy. Fortunately, it's not something that has to happen all at once, and even small steps in self-care can take you a long way. Natural fiber sources that can be eaten raw, such as vegetables, fruits, seeds, and nuts, are generally easier to incorporate. Cooking and baking tend to be the bigger challenge. Beyond the fiber-rich, exciting dishes of Mediterranean, Middle Eastern, and Far Eastern cuisine, the fiber content of popular Hungarian dishes can also be boosted, so family members who are resistant to new foods can keep enjoying their favorite meals in a healthier version. Of course, for those whose diet has until now consisted mainly of ultra-processed foods and fast food, introducing vegetables, legumes, and wholegrains represents a significant change. A colorful combination of fibers: cooked, baked, and raw When you steam, boil, sauté, or bake plant-based ingredients, their fiber content stays in the finished dish, although the size and properties of the fibers are altered by the cooking process. This is actually one of the purposes of heat treatment: to make the nutrients locked within the fiber matrix accessible and more digestible. Without cooking, most fiber-rich ingredients simply couldn't be eaten, meaning you'd miss out on their valuable nutritional content. Vegetable soups, vegetable-based one-pot dishes, wholegrain side dishes, and dried legumes all enrich your diet with a variety of fibers. Of course, it's also worth including raw plant ingredients, fruits, seeds, and nuts in your diet every day. When it comes to baking ingredients, you can take a "fiber-forward" approach as well. Instead of traditional recipes built on white flour, sugar, eggs, and margarine, try using higher-fiber flours, ground seeds, beans, chickpeas, oily seeds, nuts, poppy seeds, coconut, and cocoa for both sweet and savory baked goods. Fiber-conscious cooking can start with upgrading your existing favorite dishes. Here are some concrete ideas to get you started. Practical tips for increasing fiber content Serve cream soups with dry-toasted seeds or cooked pearl barley instead of soup pearls or croutons. In meat-based dishes, you can mix in an equal amount of red beans, white beans, or chickpeas alongside the meat. In a pinch, unseasoned canned versions work perfectly well. Legumes are also available in flour and pasta form: chickpea flour can be used to thicken soups and stews in a Greek yogurt roux, and red lentil pasta is a great alternative to traditional white pasta — and it's delicious. Leftover wholegrain bread can be dried out thoroughly, crushed, and used as breadcrumbs for coating. In that case, bake the meat or vegetables in the oven rather than frying them in oil. Oat bran can be added to cottage cheese dumplings, layered dishes, or meatballs — almost any version can handle a tablespoon or two. In recipes for meatballs or meat loaf, the white bread or bread roll can be replaced with wholegrain bread or a combination of rolled oats and oat bran. Oat flour or rolled oat flour can replace wheat flour in mildly sweet dishes such as sauces, vegetable stews, pancakes, and chocolate cookies — it can be swapped in a 1:1 ratio for white flour. In layered vegetable bakes, white rice can be replaced with brown rice, bulgur, or pearl barley. For a healthier twist, use ground turkey and live-culture Greek yogurt instead of fatty sour cream. Bulgur is a fiber-rich side dish, especially when combined with vegetables. This cracked durum wheat is a friendly ingredient that softens quickly — after bringing it to a boil, cover it and let it rest, or keep it on the lowest heat until it has absorbed twice its volume in water. Ground almonds and oily seed flours are expensive, but they make a significant difference to the fiber content of sweet baked goods and savory pastries, and everything tastes better with them. An oat flour and rolled oat cookie with ground walnuts and dark chocolate, lightly sweetened, is a real fiber bomb. If any are left over, you can keep them at the office or in the car for busy days. A walnut or almond or two can always be placed on top of oat cookies or muffins, and most mixed batter recipes can be enriched with a spoonful or two of roughly chopped almonds, walnuts, or even desiccated coconut. Sprinkle sesame seeds, flaxseeds, sunflower seeds, or pumpkin seeds on top of bread rolls and savory sticks: they add valuable nutrients and fiber even to traditional white flour recipes. Increase your fiber intake gradually Fiber is beneficial, but don't overdo it. If you're starting from a low fiber intake, switching to several high-fiber meals a day all at once is too big a change for your digestive system and may also catch your microbiome off guard. By increasing fiber intake gradually, the initial bloating and gas that some people experience can usually be avoided. Alongside fiber-rich cooked dishes, let raw or minimally processed vegetables and fruits, wholegrain breads and baked goods, and nuts and oily seeds all contribute to your daily fiber intake. You can also supplement this with additive-free, natural fiber extracts. And don't forget to drink enough water: aim for 50 ml of fluid per gram of fiber, which means a daily intake of 2 liters will reliably cover your needs. Sources used: Soltész E., Gajda Z. Fiber is good! Budapest: BOOOK Publisher; 2020

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May 16, 2026

Why We Think We're Eating Enough Fiber — and Why That May Not Be the Case

3-minute read · Maria Balogh If you asked most people, they'd answer confidently: "I pay attention to what I eat." "I eat vegetables and fruit." "I think my fiber intake is fine." And yet: both research and real-world experience tell a different story. How much fiber should we be eating, and how much are we actually eating? The widely accepted recommendation is that adults should consume a minimum of 25 grams of dietary fiber per day, with 30 grams being the ideal. In reality, data and domestic experience suggest that average intake sits closer to 15–20 grams per day. This isn't a dramatic shortfall that appears overnight. It's a slow, barely noticeable gap that builds up over years and makes its effects felt gradually. So why do we think our fiber intake is fine? 1. Because we associate fiber with too narrow a range of foods Most people automatically link fiber with: Vegetables Fruit Wholegrain bread These are indeed important sources of fiber. The problem is that fiber isn't limited to these foods alone. Research shows that: the vast majority of consumers recognize vegetables and fruit as fiber sources, there is far more uncertainty when it comes to wholegrain cereals, knowledge gaps are significant for legumes and seeds, and most people have never even heard of functional fibers such as inulin, psyllium, or resistant starch. In other words, our diets are often built on a narrower variety of fiber sources than we might think. 2. Because we only associate fiber with digestion For many people, the word "fiber" brings just one thing to mind: digestion. But the role of dietary fiber is far more complex than that. Adequate fiber intake: supports the balance of the gut microbiome, contributes to the feeling of fullness, can help with weight management, has a beneficial effect on blood sugar levels, plays a long-term role in cardiovascular health, and is linked to overall metabolic health. Different types of fiber contribute to different health benefits. This is why it matters not only how much fiber we eat, but also what types we consume and how varied our sources are. In short: it's worth broadening the range of foods from which we get our dietary fiber. Why does varied fiber consumption matter? Not all fiber is the same. Different plant sources nourish the gut in different ways: vegetables and fruit provide different types of fiber, wholegrains offer a different structure again, legumes and seeds are particularly valuable sources, and functional fibers can complement the diet in a targeted way. The more varied our fiber sources, the more balanced the overall effect is likely to be. How can you find out where you stand? Most people don't consume too little fiber because they don't care about their health. They simply don't have a full picture of the situation. The activé FiberShake Fiber Calculator can help with that. After completing the calculator, you'll get a clearer sense of which fiber sources dominate your diet and which types you might benefit from eating more of. Your responses also contribute to building a broader picture of which fiber sources are well known in Hungary and which ones are rarely used in everyday eating. A small step toward more mindful fiber consumption Fiber is not a trend, not a quick fix, and not just a "digestive issue." Fiber is a fundamental part of a healthy diet. You don't need to change everything overnight. The first step is simply knowing where you stand right now. After that, the choice is yours. References: Consumers' knowledge about dietary fiber – full PDF (Szűcs V., 2016)Awareness and Knowledge Regarding the Consumption of Dietary Fiber (MDPI, 2020)Perception of dietary fiber and consumption behaviorsKnowledge and attitudes regarding dietary fibers

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May 16, 2026

The secret to detoxification lies within you and in Fiber

4-minute read · Erzsébet Soltész, dietitian What comes to mind when you hear the word "detox"? "Detox tea," "detox cure," "detox diet," "liver detox drops" — these all promise to cleanse you of accumulated toxins. The good news is that you don't need them: your body already has a perfectly tuned detoxification system. Several of your organs work tirelessly to eliminate all unnecessary and dangerous substances. Your disposal team also includes a member who has only recently come into the spotlight. It was just a decade or two ago that the key role of the microbiome in the body's detoxification processes was discovered. What keeps your built-in detox arsenal working well? Not random "miracle products"... You can support the health of your digestive system and the detoxification work of your gut microbiome by consuming at least 30 grams of fiber daily from a combination of different fiber types. Here's how to make the most of their mutually reinforcing effects: Some types of fiber, such as psyllium, work physically, helping to sweep harmful substances out of the body. Prebiotic fibers, such as inulin, act as food for beneficial bacteria, supporting the growth of helpful microbes and enabling them to carry out their detoxification work effectively. Probiotic foods containing live bacterial cultures are a welcome addition, as they create a favorable environment in your digestive system. Your detox team Get to know your body's detoxification system and the microbiome friends within it: Your liver is your central detoxification organ, a biochemical powerhouse that converts harmful substances, both ingested and internally produced, into forms your kidneys and digestive system can safely eliminate. It also breaks down alcohol and drug residues. Your kidneys function like intelligent water filters, continuously drawing water-soluble waste and toxic compounds out of your bloodstream and excreting them in urine. Your lungs serve as an exhaust system, expelling unnecessary gases and volatile compounds with every breath. Your skin releases mineral salts and toxins through sweat. Your colon is the primary detoxifier in your digestive tract, flushing out not only undigested food residue but also toxins produced within the body. Your microbiome acts as an additional line of defense, accelerating the removal of toxic compounds, supporting immune function, and even reinforcing the liver's detoxification work. Three protective shields: the main lines of defense in detoxification Three lines of defense protect you from harmful environmental influences every day. Your microbiome is the first line of defense, your intestinal wall is the second, and your liver is the third. They rely on one another to keep you safe. The microscopic community in your digestive tract comes into direct contact with pathogens from the outside world, undigested food debris, and environmental contaminants. Your tiny residents neutralize a range of toxic substances using their own chemical arsenal, and displace and destroy disease-causing microbes. Your microbiome is in constant communication with the nerve network and immune cells woven through your intestinal wall, and together they regulate what passes through. The intestinal wall acts as a dynamic barrier, ensuring that only what is necessary for your body's healthy functioning enters your bloodstream, while harmful substances are kept out. The intestinal wall cells that form the foundation of this defense system are coated with an additional layer of mucus, which is maintained by the friendly bacteria of your microbiome. When this barrier is intact, harmful compounds, bacterial debris, and inflammatory substances cannot enter your circulation. Should anything inappropriate get through, your liver filters it out. Your central detoxification organ interacts with your microbiome via the gut-liver axis. The liver uses specialized immune cells to remove toxic metabolites produced by the microbiome and also influences the composition of the microbiome itself. Everyday microbiome support with fiber Your built-in defense system works day and night without pause. You don't need capsules, teas, or elaborate cures. What you can genuinely do to support your detoxification organs and your microbiome is to practice self-care and take responsibility for your own health. Start with small changes and gradually build sustainable new habits: As part of a balanced, varied diet, aim to consume at least 30 grams of fiber per day from a combination of several fiber types. Always drink enough water with fiber-rich meals: allow for approximately 50 ml of liquid per gram of fiber. Exercise regularly. Consistent, moderate physical activity benefits your microbiome and supports healthy immune function. Avoid ultra-processed foods, smoking, and excessive alcohol consumption. When choosing a fiber supplement, opt for a product that combines multiple fiber types and is free from artificial sweeteners and additives. Sources used: Soltész E., Gajda Z. Fiber is good! BOOOK Publisher; 2020 Soltész E. Supporting the microbiome – fiber-conscious nutrition (working title, manuscript). Expected publication: BOOOK Publishing; 2025 Collins SL, Patterson AD. The gut microbiome: an orchestrator of xenobiotic metabolism. Acta Pharm Sin B. 2020;10(1):19-32. Claus SP, Guillou H, Ellero-Simatos S. The gut microbiota: a major player in the toxicity of environmental pollutants? NPJ Biofilms Microbiomes. 2016;2:16003. Das A, Srinivasan M, Ghosh TS, Mande SS. Xenobiotic Metabolism and Gut Microbiomes. PLoS One. 2016;11(10):e0163099. Koppel N, Maini Rekdal V, Balskus EP. Chemical transformation of xenobiotics by the human gut microbiota. Science. 2017;356(6344):eaag2770. Young O. The Vital Role of the Liver in Human Physiology. J Gastrointest Dig Syst 2023;13:782.

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