What losing weight would actually buy you

How to read any of this

Every number above is what happened to the people in a named clinical trial. None of it is a result from this clinic, a prediction for you, or a promise. Trial populations are selected, and individual results vary widely, in both directions.

Two of them need particular care and the tool says so on the card itself. The diabetes remission figures come from a trial that enrolled people with diabetes of six years or less who were not on insulin, and they do not transfer to someone with fifteen years of diabetes on insulin. The liver figures come from a Cuban study, and Indians develop liver fat at a lower body weight than the people in it.

Three things this tool deliberately does not tell you

• That you will live longer. For weight loss through lifestyle change, there is no trial that has demonstrated reduced overall mortality. It may well be true. It has not been shown, and this page is not going to imply it.
• That your heart attack risk falls. A secondary analysis of one large trial found that losing 10 per cent or more was associated with about 21 per cent fewer heart events in people with type 2 diabetes. But that trial's main result was null: it did not show a benefit overall, and it was stopped early for futility. That is promising, not proven, and the distinction matters.
• That you should delay fertility treatment to lose weight first. A randomised trial of 577 women with obesity and infertility found that a six month lifestyle programme before fertility treatment resulted in fewer live births than going straight to treatment. Weight management and fertility treatment should run alongside each other. If you are under fertility care, do not postpone it for this.

Why five per cent is the number to aim at first

People arrive wanting to lose thirty kilos and are disappointed to be offered five per cent. Look at what five per cent actually does in the tool above. Blood pressure moves. Triglycerides move. Liver inflammation starts to resolve. In someone with recent diabetes, roughly one in fourteen is already in remission by five kilograms.

Five per cent of 90 kg is four and a half kilograms. It is the most under-rated number in this entire field.

Sources are named on each card. Diabetes prevention: Hamman RF and colleagues, Diabetes Care 2006;29:2102-2107. Remission: DiRECT, Lean MEJ and colleagues, Lancet 2018;391:541-551 and the 2 year results, Lancet Diabetes and Endocrinology 2019;7:344-355. Blood pressure: Neter JE and colleagues, Hypertension 2003;42:878-884. Liver: Vilar-Gomez E and colleagues, Gastroenterology 2015;149:367-378. Sleep apnoea: Peppard PE and colleagues, JAMA 2000;284:3015-3021. Knee: Messier SP and colleagues, Arthritis and Rheumatism 2005;52:2026-2032 and Arthritis Care and Research 2018;70:1569-1575. PCOS: BAMBINI post hoc analysis, Human Reproduction 2026;41:809-817. Lipids: Dattilo AM and Kris-Etherton PM, American Journal of Clinical Nutrition 1992;56:320-328. Fertility: Mutsaerts MAQ and colleagues, New England Journal of Medicine 2016;374:1942-1953. Cardiovascular: Gregg EW and colleagues, Lancet Diabetes and Endocrinology 2016;4:913-921.