Visceral adipose tissue (VAT)

Not all body fat sits in the same place or behaves the same way. Subcutaneous fat is the layer you can pinch under the skin. Visceral adipose tissue is packed deep inside the abdominal cavity, wrapped around the liver, pancreas and intestines. Two people at the same weight can carry very different amounts of it, which is part of why the scale alone is a blunt instrument.

Visceral fat is metabolically noisy. It drains directly into the portal vein feeding the liver and releases inflammatory signals and free fatty acids in a way subcutaneous fat largely does not. That is the mechanistic story behind why waist measurement adds information a BMI does not, and why two people with identical BMIs can have very different blood pressure, triglycerides and liver enzymes.

GLP-1 trials capture this indirectly through waist circumference, which tracks abdominal fat. In SURMOUNT-1, tirzepatide reduced waist circumference alongside body weight in adults with obesity, and in the ATTAIN-1 oral GLP-1 trial waist circumference, systolic blood pressure, triglycerides and non-HDL cholesterol all improved significantly versus placebo. Those are the markers visceral fat drives.

The common confusion is believing you can target it. There is no exercise, food or supplement that removes fat from the abdomen specifically — spot reduction is not a thing the body does. What happens is that overall fat loss tends to draw disproportionately from visceral stores early on, which is why waist and blood pressure often improve faster than the scale suggests they should. If your waistband is looser and your labs are better while the scale has barely moved, that is a real result, not a consolation prize.

Worth asking your clinician: whether your waist circumference is being measured at each visit, not just your weight, and which of your lab markers they are watching as the fat comes off. Our BMI calculator is a starting point, and the muscle-preservation protocol explains how to keep the loss weighted toward fat rather than lean tissue.