When it comes to shifting body fat, most people think about cutting calories, but one of the most powerful tools is right on your plate: fibre. Not only does fibre intake keep your digestion running smoothly, but it also plays a surprisingly big role in controlling appetite, regulating blood sugar, and it even influences how many calories your body actually absorbs. Here is what the science is saying about how dietary fibre can support your body composition goals. And the best thing? Leaning into more fibre is one of the simplest daily upgrades you can make for long-term health as well.
1. Fibre Helps You Feeling Full
One of the most well‑established ways that dietary fibre supports fat loss is through satiety - the feeling of fullness that helps control how much we eat. High‑fibre foods require more chewing and take longer to eat, naturally slowing the pace of a meal. This increase in oral processing stimulates stretch receptors in the stomach earlier in the eating process, which helps signal to the brain that you’re getting full before consuming excess calories.
Additionally, the physical bulk of fibre distends the stomach, which stretches the walls and sends signals to the brain that you’re full. This combination of slower eating, extra chewing, and physical fullness helps prevent overeating at that meal and keeps you satisfied for longer.
Research shows that an increase in dietary fibre intake is associated with reduced hunger and prolonged satiety, likely contributing to lower overall energy intake and, over time, reduced body weight or fat mass in controlled settings. (1)
2. It Slows Digestion + Blunts Blood Sugar
Soluble fibres, such as beta‑glucans from oats or pectins from fruits and legumes, form a viscous gel in the stomach. This gel slows gastric emptying, meaning food stays in the stomach longer before entering the small intestine. In practical terms, this delays the absorption of nutrients, particularly carbohydrates, resulting in a more gradual rise in post‑meal blood glucose and corresponding insulin levels.
Blunting glucose and insulin spikes are important because sharp blood sugar fluctuations can trigger as sharp of a fall and subsequently, more hunger and cravings, leading to increased calorie intake later in the day. By smoothing these responses, viscous fibres help stabilise energy availability and reduce hunger rebounds.
Several controlled studies highlight this mechanism, demonstrating slower carbohydrate absorption and improved post‑meal glucose control when meals include viscous fibres. (2)
3. Fibre Influences How Many Calories You Absorb
Beyond simply making you feel full, fibre can influencer calorie absorption. Some fibres increase the viscosity of intestinal contents and can bind fats and bile acids, which means a small amount of fat and starch passes through our system undigested and is excreted in the stool. While the energy savings at each meal is modest, over days and weeks this can add up to a meaningful reduction in net calorie uptake, without restricting any food volume.
This mechanism is supported by research showing that fibre’s physical structure interferes with the complete digestion of certain nutrients and speeds transit through the gut, effectively lowering the energy extracted from the same food compared to a low‑fibre meal. (2)
4. Fibre Shapes Gut Hormones That Control Appetite
Perhaps the most exciting and biologically specific mechanism linking fibre to fat loss involves the gut microbiome and appetite signalling hormones.
Many types of fibre, especially fermentable fibres like inulin, resistant starch, and some oligosaccharides, are not digested in the small intestine but instead reach the colon where they are fermented by bacteria. This fermentation produces short‑chain fatty acids (SCFAs) like acetate, propionate, and butyrate.
SCFAs are signalling molecules that interact with specialised receptors on gut endocrine cells (called L‑cells). In response, these cells increase secretion of appetite‑regulating hormones such as glucagon‑like peptide‑1 and peptide YY (PYY). Both of these naturally slow gastric emptying, enhance satiety, and send signals to the brain that decrease hunger and reduce calorie intake. (1)
Randomised trials that focus on fermentable fibres have shown corresponding increases in circulating hormones involved in appetite signalling alongside improved satiety and modest weight loss over time, reinforcing the importance of this hormonal pathway. (3)
How to increase your fibre intake:
Increasing your fibre intake is easiest when you layer in some extra fibre into every meal and snack. Try building your dinners around lentils and beans as your starchy sides over things like potato, pasta and rice – 1 cup of cooked lentils gives you an impressive 156g of fibre.
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Legumes + beans: Lentils, chickpeas, cannellini beans, black beans etc. Serve as a main, side, or add to salads, soups, stews, or blend into dips. You can even blend them in your smoothies.
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Fruits: Berries, apples, pears, and (slightly green) bananas for an easy daily boost. Avocados are also a great source of fibre, alongside healthy fats.
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Nuts + seeds: Chia, ground flax, pumpkin seeds, almonds etc. Sprinkle onto yoghurt, oats, salads, or soups, or have alongside an apple for a great high fibre snack.
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Oats: Start the day with oats (or add oats to smoothies/overnight oats) and top with fruit + seeds for a double hit. Pro tip – overnight oats will give your more bang for your buck when it comes to fibre AND protein.
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Vegetables: Broccoli, Brussels sprouts, carrots, spinach, and peas are some of our favourites. Aim for 2–3 different colours across the day.
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Prebiotic fibres: Prioritise onions, garlic, leeks, asparagus, and slightly green bananas, plus cooked-and-cooled oats or potatoes to help feed beneficial gut bacteria. If you need an easy boost to your breakfast, consider Essential Fibre+, which has 7g per serving.
Disclaimer: The information presented in this article is for educational purposes only and is not intended to diagnose, prevent, or treat any medical or psychological conditions. The information is not intended as medical advice, nor should it replace the advice from a doctor or qualified healthcare professional. Please do not stop, adjust, or modify your dose of any prescribed medications without the direct supervision of your healthcare practitioner.
References:
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Akhlaghi M. The role of dietary fibers in regulating appetite, an overview of mechanisms and weight consequences. Crit Rev Food Sci Nutr. 2024;64(10):3139-3150. doi: 10.1080/10408398.2022.2130160. Epub 2022 Oct 4. PMID: 36193993.
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Miller S (2024). Dietary Fiber Intake: A Strategy to Combat Obesity. J Nutr Weight Loss. 9:209.
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Adam, C.L., Williams, P.A., Dalby, M.J. et al. Different types of soluble fermentable dietary fibre decrease food intake, body weight gain and adiposity in young adult male rats. Nutr Metab (Lond) 11, 36 (2014). https://doi.org/10.1186/1743-7075-11-36
