Natto, a traditional Japanese food made from fermented soybeans, is recognized for its unique, sticky texture and strong, pungent flavor. While its taste is often described as an acquired one, its dense nutritional profile has earned it a reputation as a health-promoting food. Natto’s potential to aid in weight loss centers on its specific combination of macronutrients and the beneficial compounds created during fermentation. This analysis explores how natto’s composition and its impact on the gut microbiome may support weight management efforts.
Natto’s Weight Management Nutrient Profile
Natto provides a substantial amount of protein and fiber, two macronutrients associated with increased satiety and better appetite regulation. A typical 100-gram serving contains approximately 19 grams of protein, over 5 grams of dietary fiber, and about 211 calories. This combination makes it a relatively low energy-dense food that promotes a feeling of fullness. The high protein content helps increase the body’s energy expenditure following a meal, known as the thermic effect of food.
Protein requires more energy to digest and metabolize compared to fats and carbohydrates, contributing to a temporary increase in calorie burn. The fiber in natto includes both soluble and insoluble types. Soluble fiber forms a gel-like substance in the digestive tract, slowing down gastric emptying and prolonging satiety after eating.
Probiotics and Metabolic Regulation
Natto’s fermentation process with the bacterium Bacillus subtilis (B. natto) introduces elements that influence metabolic health. This bacterium acts as a probiotic, modulating the gut microbiome, which plays a direct role in energy balance and weight regulation. Changes in the balance of gut bacteria are linked to differences in how the body stores fat and regulates appetite.
The fermentation process generates short-chain fatty acids (SCFAs), such as butyrate, when gut bacteria metabolize natto’s fiber. These SCFAs serve as energy sources for colon cells and act as signaling molecules that influence metabolism. SCFAs can stimulate the release of gut hormones, specifically GLP-1 and PYY, which signal to the brain to reduce appetite and increase feelings of fullness. Research has also shown that B. natto can regulate metabolic pathways, reducing fat accumulation and improving lipid profiles.
Incorporating Natto into a Weight Loss Plan
For individuals aiming for weight loss, natto must be integrated into a calorie-controlled diet without introducing excessive hidden calories. The standard recommended serving size is typically one to two small packs (around 40 to 50 grams each) per day. This portion delivers beneficial probiotics and fiber without significantly impacting daily calorie goals. A common pitfall is the addition of high-calorie traditional toppings, such as large amounts of white rice, soy sauce, or excessive karashi mustard. To avoid calorie creep, consumers can opt for low-calorie flavor enhancers like a small dash of rice vinegar or ponzu sauce.
Managing the pungent taste and sticky texture is often the biggest barrier to consistent consumption. Choosing milder varieties, such as hikiwari (minced natto), or pairing it with strong, fresh flavors like grated ginger or aromatic herbs can make it more palatable. Other low-calorie additions include chopped scallions, kimchi, or a few drops of sesame oil. Incorporating natto into non-traditional dishes like salads or omelets also helps mask its unique characteristics, making it a sustainable addition to a long-term weight management strategy.