Overweight & obesity (BMI)

Visceral fat usually goes first when overall weight drops.

Both together cut belly fat more effectively than either alone.

Promote storage in the abdominal area.

GLP-1 agents slow stomach emptying and damp the hunger signal in the brain — weight falls for as long as they are taken and rises again in most people after stopping. They take away hunger, not habit; keeping muscle through protein and strength work belongs alongside, otherwise muscle is lost too.

BMI divides weight by height squared: overweight from 25, obesity from 30. It does not distinguish muscle from fat and says nothing about distribution — waist size does that: above 88 centimetres in women and 102 in men, risk rises independently of BMI. Five to ten per cent weight loss lowers blood pressure, sugar and fats measurably; that is the order of magnitude studies work with.

It is measured halfway between the lowest rib and the hip bone, standing, at the end of breathing out. Where the fat sits weighs more for the risk than how much there is in total.

With a lot of muscle it shows too much, in older people with little muscle too little. Build, background and water retention shift it too. It is a starting point, not a verdict.

Velvety dark skin on neck and armpits, skin tags, snoring with pauses in breathing, high blood pressure, breathlessness in everyday life, joint pain in knee and hip, heartburn. These signs say more about urgency than the weight does.

A fast rise within weeks, with swollen legs or breathlessness, is water rather than fat. Cortisone, certain drugs for depression and psychosis, a sluggish thyroid and an excess of cortisol also belong on the list.

Belly fat promotes insulin resistance — long-term sugar rises.

Typically raised with visceral fat.

Often falls as belly fat increases.

Fat tissue is metabolically active and mildly pro-inflammatory.

Low values are common with raised body weight because the vitamin is bound in fat tissue. Correcting it makes sense; as a means of losing weight there are no studies.

Involved in the action of insulin inside the cell. With poorly controlled sugar it is lost through the urine — a circle that can be closed.

Metformin lowers the uptake measurably over years. With tingling in the feet under this treatment B12 belongs checked before it is put down to nerve damage from the sugar.

They slow the uptake of sugar from the meal and satisfy for longer. Pulses, oats, vegetables and wholegrain work differently from a powder out of a tin.

Swells in the stomach and satisfies. Studied at 3 g a day with plenty of water before meals; the weight effect in studies is a few kilograms over weeks. Taken dry it can swell in the oesophagus.

One of the best-selling weight-loss products. Reviews find a difference of about 900 g compared with placebo — and reports of liver damage. Both belong named together.

Clearly worthwhile and well studied when deficient; fewer data for the wider uses. Fat-soluble — check blood levels at high doses.

Effective when deficient; effects on sleep and stress plausible but moderate. Too much causes loose stool.

Clearly worthwhile and well supported when deficient — vegan, older adults, certain drugs. No energy boost without a deficiency.

Central to the development and persistence of belly fat.

In studies 25–30 g protein per meal and 25–30 g fibre a day satisfy markedly longer than the same energy from white flour and sugar.

0.5–1 kg a week is the range where muscle is largely kept and gallstones are rare. Faster usually costs muscle and returns more often.

Drinks satisfy little. A litre of sweetened drink brings about 400 kcal that the body does not subtract at the next meal.

More important for keeping weight off than for losing it — the two together work.

At the same calorie count, fibre satisfies for noticeably longer.

Too little sleep shifts the hunger hormones — almost always overlooked when losing weight.