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.
Visceral fat is the fat that accumulates in the abdominal cavity, around organs such as the liver, pancreas and intestines. It differs fundamentally from subcutaneous fat, which sits directly beneath the skin. Subcutaneous fat acts as a kind of buffer: it stores excess energy in a relatively safe way. Visceral fat does not, and when it is present in excessive amounts it behaves like an active and harmful organ.
The biggest problem is where visceral fat sits. It borders directly on the portal vein, the blood vessel that leads to the liver. This means that fatty acids and irritating substances produced by visceral fat travel straight into the liver. That disrupts the liver's normal workings, encourages fat to build up there, and prompts the liver to produce more harmful blood fats. Subcutaneous fat does not have this direct route to the liver.
Visceral fat contains more immune cells than subcutaneous fat and releases more inflammation-promoting substances. That low-grade inflammation underlies insulin resistance (your cells respond less well to sugar in your blood), high blood pressure, low HDL cholesterol ('good' cholesterol) and high triglycerides (a type of fat in your blood). All of those factors together raise your risk of cardiovascular disease and type 2 diabetes, even if you are not overweight. So you can have a normal body weight and still carry a dangerously large amount of visceral fat.
When visceral fat becomes chronically overloaded, fat starts ending up in places where it does not belong at all: inside liver cells, the heart muscle, the pancreas and the skeletal muscles. This further disrupts the functioning of those organs. At the same time, the fat cells themselves become damaged and begin to age and show scarring, making the tissue even less functional.
The good news is that visceral fat responds relatively well to lifestyle changes. When weight is lost through eating less and moving more, visceral fat decreases faster than subcutaneous fat. Measuring your waist circumference is a more useful indicator for this than body weight alone, because it better reflects how much visceral fat is present. Medications and hormone therapies that can reduce visceral fat also exist, but these sometimes carry serious side effects and are not suitable for everyone; discuss this with your doctor.
This answer is based on several large scientific overviews. It draws largely on combined research in people, in which the links between visceral fat and cardiometabolic risk have been clearly and repeatedly confirmed. The cause-and-effect relationship is biologically well supported through the portal-vein hypothesis, although part of the evidence rests on comparative and mechanistic research. Evidence on the effects of hormonal therapies is thinner and the safety risks remain uncertain.
How dangerous is a fatty liver (hepatic steatosis)?
For most people a fatty liver is stable for the time being, but it substantially raises the risk of cardiovascular disease, diabetes and liver disease; losing weight is so far the only proven way to limit the damage.
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 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.
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.
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.
Why does starch have a higher glycaemic index than sugar?
Starch consists largely of amylopectin, a heavily branched chain that is broken down quickly and therefore causes a higher blood sugar spike than sugar. The preparation method and physical structure of the food also determine how high that spike turns out to be.