Belly fat

Not all belly fat is the same: the soft layer directly under the skin (subcutaneous fat) is fairly harmless to your health. Visceral fat, by contrast, sits deep inside the abdomen between the liver, intestines and kidneys – and it behaves like an active organ. It releases fatty acids and inflammatory messengers straight into the liver, interferes with the action of insulin and raises blood pressure and blood lipids. That's why waist circumference is a better risk marker than overall weight.

The World Health Organization sets these waist circumference thresholds: for women, the risk is increased from 80 cm and substantially increased from 88 cm; for men, from 94 and 102 cm respectively. Even more telling is the waist-to-height ratio (WHtR), which should be below 0.5. Measure in the morning on an empty stomach, midway between your lowest rib and the top of your hip bone, after breathing out normally.

Why does fat collect on the belly in particular? Genetic make-up and sex play a part – men tend to be “apple-shaped”, while women tend to be more “pear-shaped” until the menopause. On top of that come chronic stress with high cortisol, lack of sleep, alcohol, sugary drinks and lots of sitting. Even slim people can have too much visceral fat on the inside if they hardly move.

The good news: visceral fat responds particularly quickly to exercise. Studies show that regular endurance activity – 150 minutes of brisk walking a week is enough – measurably reduces belly fat even when the scales barely budge. Targeted ab exercises, on the other hand, do nothing for the fat layer: you can't “spot-reduce” fat in one place, only lose it overall. Core strength training is still worthwhile, though – for your posture and your back.

In children, a growing waistline is an early warning sign that the paediatrician assesses using percentiles; more activity in everyday family life and water instead of soft drinks have the strongest effect here.