Subcutaneous or visceral fat: the difference that counts

Subcutaneous fat sits directly under your skin and you can pinch it between your fingers. Visceral fat sits deeper, inside your abdominal cavity between your organs, and is metabolically more active. That second type is more strongly associated with blood values such as triglycerides and fasting insulin, even in people at a normal weight.

That last sentence is why this article exists. You can look lean and still carry the type of fat that shifts your blood values.

What is the difference between subcutaneous and visceral fat?

The location, and what the tissue does. Subcutaneous fat lies between your skin and your muscles and mostly serves as storage and insulation. Visceral fat lies behind your abdominal wall, around your liver and intestines, and actively releases fatty acids and signalling substances into your blood.

For the record: neither is bad in itself. You need both. It is about the ratio and the amount.

Why is visceral fat metabolically more active?

Because of where it sits and how its cells behave. Fatty acids from visceral tissue reach your liver first through the portal vein, before the rest of your body sees them. This tissue also releases more inflammatory signals. Research describes that combination as a route towards insulin resistance and altered blood lipids.

This is set out in a position statement on visceral and ectopic fat (Neeland et al., 2019). Subcutaneous fat comes out considerably more neutral in the same work.

Put simply: subcutaneous fat is a warehouse. Visceral fat is a warehouse that also sends emails.

Can you tell from your body which fat you carry?

Partly. A belly that feels soft and lets you grab a fold is largely subcutaneous fat. A belly that feels firm and tight while still pushing forward more often points to visceral fat. You cannot be certain with a tape measure, let alone by eye.

The hard belly that will not pinch is often misread as "muscular". Sometimes that is right. Sometimes the fat is simply behind it.

Waist circumference therefore remains the most usable home measure, and is described in the literature as a practical indicator (Ross et al., 2020). How to take it without error is in measuring your waist.

Why do lean people sometimes carry a lot of visceral fat?

Because weight and fat distribution are two different things. Some people store relatively little fat under the skin and relatively much inside the abdominal cavity. They look lean while their blood values tell a different story. In the literature this pattern is sometimes called TOFI: thin outside, fat inside.

This is the scenario I run into most often in practice. A lifter at 78 kilos with visible abs, and yet triglycerides and fasting insulin that read higher than expected. His mirror is not lying, it just is not telling the whole story.

Genetics play a part here, as do age, sleep and alcohol. Fat distribution also differs between men and women, and shifts for women around menopause.

That is exactly why a BMI of 23 gives you little reassurance. There is a reason the Dutch RIVM uses waist circumference alongside weight in its Lifestyle Monitor.

Which fat disappears first when you lose weight?

In an energy deficit, visceral fat often appears to move relatively early, while the last subcutaneous spots usually hang around longest. That explains why your metabolic values can improve before that final belly fold is gone. Good news, because it means early progress is real.

The lower belly and the flanks are the last areas for many people. That is not a failure of your programme, that is sequence.

How to approach that process practically is in reducing visceral fat and, if you are mid-cut, in cutting.

What does your blood say about the difference?

No blood value measures directly where your fat sits. But several values shift more often with visceral fat than with subcutaneous fat: triglycerides, HDL cholesterol, fasting insulin and liver values such as ALT. That makes them useful alongside the tape measure, not as a replacement for it.

In practice you would usually look at triglycerides, fasting insulin and ALT. The insulin side can be brought into view with fasting insulin and HOMA-IR.

What those values mean together is explained in visceral fat and, more broadly, in measuring metabolic health. For the insulin side itself, insulin resistance is the starting point.

Be careful drawing conclusions from a single measurement. These values can deviate for all sorts of reasons, and they establish nothing on their own.

Pick up a tape measure tomorrow morning and write down your waist, fasted. That number tells you more about this distinction than an hour in front of the mirror.

References

• Neeland IJ et al. Visceral and ectopic fat, atherosclerosis, and cardiometabolic disease: a position statement. Lancet Diabetes Endocrinol, 2019. PMID 31301983
• Despres JP. Body fat distribution and risk of cardiovascular disease: an update. Circulation, 2012. PMID 22949540
• Ross R et al. Waist circumference as a vital sign in clinical practice. Nature Reviews Endocrinology, 2020. PMID 32020062
• RIVM, Lifestyle Monitor, figures on waist circumference and overweight in the Netherlands.

Every blood test result includes a professional assessment from a BIG-registered doctor. For treatment decisions, discuss your results with your GP.