Good news for the seriously fat: if you survive your heart attack your prospects are excellent.

A study has thrown doubt on the idea that being fat is a delayed form of suicide. Obesity may increase the risks of a heart attack but it also increases the chances of long-term survival afterwards.

The reasons are not known, but obese and very obese patients who have been treated for a heart attack are less than half as likely to die in the next three years as people with a normal body mass index (BMI).

The study, carried out by German and Swiss doctors, followed 1,676 patients admitted to hospitals in Bad Krozingen and Basle for unstable angina or a heart attack between 1996 and 1999. In each case the patients were investigated and treated appropriately.

Most were treated by angio-plasty with stents (opening up the blocked arteries and propping them open), while others had heart bypass operations or were treated with drugs. They were then followed up for another three years.

In the European Heart Journal the team reports: “We found that obese and very obese patients had less than half the long-term mortality when compared with normal BMI patients.”

Among patients of normal weight, 9.9 per cent had died, and among overweight patients, the figure was 7.7 per cent. Among obese patients only 3.6 per cent had died. However, not a single patient classed as very obese had died.

Heinz Büttner, the head of interventional cardiology at Herz-Zentrum, Bad Krozingen, Germany, who led the study, said: “Although there is no doubt that people who are overweight, obese and very obese have a higher risk of developing diabetes, hypertension and coronary artery disease, the evidence from our study shows once a coronary event has occurred and been optimally treated, obese patients switch to a more favourable prognosis compared to normal-weight patients.”

Among healthy people, BMI is a strong factor in mortality, so the study is no justification for getting fat. But it may be a consolation for fatter people who have had a heart attack. The puzzle is why this should happen.

Dr Büttner suggested several reasons. Fatter patients may benefit more from the drugs prescribed to control cholesterol and blood pressure after treatment. Obese patients in the study were more likely to be prescribed such drugs.

Other possible influences are the cannabis-like compounds produced naturally in the brain, the cannabinoids, the levels of which are higher in the obese, as well as lower blood-platelet counts and high triglyceride levels.

The cannabinoids may have important protective effects, the team suggests, because they dilate the blood vessels. Lower platelet counts are also protective, and high triglycerides, while increasing the risk of heart attack, may protect afterwards by reducing the risk of heart arrhythmias, a frequent cause of death in heart patients.

Dr Büttner said that, although the study provided important information, people who were obese should not delay trying to lose weight.

In the UK, two thirds of adults are now overweight or obese. In the past ten years obesity has doubled in six-year-olds and trebled among 15-year-olds

Heavy matters

— A third of adults, a fifth of boys and a third of girls will be obese by 2020

— Obesity reduces life expectancy by an average of nine years

— Obesity doesn’t happen overnight: it takes about 3,500 excess calories to gain only 1lb (0.5kg)

Source: UK National Audit Office, BBC, Times archives

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