Is brown fat really different from ordinary fat, and can I activate it?
Brown fat is a genuinely different tissue from white fat and burns energy as heat, but no proven safe way to switch it on in yourself yet exists. Supplements and food have no demonstrable effect for this purpose; cold exposure is widely discussed but still insufficiently studied in people.
Brown fat tissue is biologically fundamentally different from ordinary white fat. White fat stores energy; brown fat burns energy as heat. This happens through a specialised protein that converts the energy from fatty acids directly into heat instead of storing it. There are also intermediate forms, known as beige fat cells, which can develop from white fat and have similar properties.
In adults, measurably active brown fat tissue is rarer than long believed. On average it is detectable in about 7% of people, measured using an imaging technique that makes metabolic activity in the body visible. In people who are overweight, brown fat is still present, but it is less active than in lean people.
Whether you can activate your own brown fat through food or supplements is a separate question. An analysis of 24 studies involving 2,785 participants found no measurable effect of food or supplements, including L-arginine, on the activity of brown fat tissue. Supplements such as capsaicinoids (from peppers) and catechins (from tea) increased energy use at rest by an average of 102 kcal per day, but this was probably not through brown fat itself. For cold exposure, the best-known way to switch brown fat on, the available studies are too limited to say anything definitive.
Researchers are actively looking for ways to activate brown fat. Studies in people are under way with tirzepatide (a medicine used for excess weight), examining whether it activates brown fat and converts white fat to beige fat. That study has 34 participants and results are not yet available. Always discuss any interest in treatments like these with your doctor. There are also signals from a small study in cancer patients that immunotherapy (an intensive cancer treatment, not intended for this purpose) raises brown fat activity, but that is not an everyday approach.
This answer draws on a summary of 24 studies on food and brown fat, an overview of studies using special imaging scans that measure metabolism in adults, genetic research into fat cell types, a small look-back study in 68 cancer patients, and an ongoing study with 34 participants. The findings on the biological distinctiveness of brown fat are well supported. The claim that supplements do not, or barely, activate brown fat comes from a solid analysis, but the overall evidence on activation methods in people is thin: the available studies are small, short-term, or not yet completed.
What works better against belly fat: eating less or moving more?
Eating less has, on average, a slightly larger effect on belly fat than moving more, but the combination works best. Choose aerobic exercise when you work out, and avoid overly aggressive diets because of the risk of bone loss.
Does eating low-carb make a difference for belly fat?
Eating low-carb measurably reduces belly fat, especially if you are already overweight or have metabolic problems. Combining it with time-restricted eating works even better.
Does 150 minutes of exercise per week help reduce liver fat?
Exercise clearly reduces liver fat, and you do not necessarily need to reach 150 minutes per week to benefit. Both aerobic training and strength training help; start with what is achievable and build from there.
Which form of fasting works best against belly fat?
Alternate-day fasting and the 5:2 pattern show the strongest evidence for loss of belly fat, but the studies are short-term or small. A 10-hour eating window also works, while 8 hours on top of a healthy diet adds little extra benefit.
What is visceral fat and why is it more dangerous than subcutaneous fat?
Visceral fat is more dangerous than subcutaneous fat because it sends irritating substances and fatty acids directly to the liver, raising the risk of heart disease and diabetes regardless of your weight. Exercise and eating less help, and your waist circumference is a better indicator than the scales alone.
Does eating more fibre help against high blood sugar?
Water-soluble fibre from legumes, vegetables and fruit probably helps lower high blood sugar, but the overall composition of the meal also plays a role. For type 2 diabetes and gestational diabetes, consulting a doctor is always necessary.