Why piling on the pounds may help you live longer It was Wallis Simpson who famously remarked that "you can never be too rich or too thin." But the latest research suggests the former Duchess of Windsor got it wrong, at least where weight is concerned. The new study, the biggest on the topic to date, has found that those with a little extra padding are likely to outlive their slimmer counterparts. The research, published in the Journal of the American Medical Association last week, found, as might be expected, that people who were very obese (a Body Mass Index of over 35) had 30 per cent higher mortality than those of a "healthy" weight (a BMI between 18.5 and 25). However, those who were just overweight (a BMI between 25 and 30) were around 6 per cent less likely to die during the study than those who fell into the "healthy" weight range. Even people usually classified as mildly obese (a BMI between 30 and 35) seemed to be at no risk of dying early. While severe obesity is an established risk for conditions like heart disease and diabetes, some modest extra poundage is linked with increased longevity - a phenomenon known to experts as the "obesity paradox." "We don't fully understand why it occurs, but one explanation is that overweight people may be more likely to have health problems, like high blood pressure and diabetes, flagged up and treated," says Paul Gately, professor of exercise and obesity at Leeds Metropolitan University. Having a higher BMI seems to be protective for some chronic conditions like heart failure, too, and research is underway to explain this. What the latest research does highlight is the shortcomings of the BMI, a rough estimate of body fatness based on weight and height, as an overall gauge of health (to work yours out, divide your weight in kilograms by your height in metres squared - or use an internet BMI calculator). Although a BMI between 18.5 to 25 is regarded as the ideal, most experts now accept that those who carry a stone or two more can remain perfectly well, provided they eat a balanced diet and take some exercise to keep heart, arteries and blood glucose levels healthy. BMI is also an imprecise tool because it does not take into account where body fat is deposited. Studies have shown that people who lay fat around their hips and thighs are at lower risk than those who deposit it around their stomachs (the apple shape), whatever their BMI, which is why doctors think waist measurement is key (the ideal being less than 32" for women and less than 37" for men). The measurement is also inaccurate for those with a muscular build who will register a high BMI despite being fit and healthy. "What the latest research is telling us is that the biggest risks are with the very obese, and this is where we should be focusing our funding and research," says Prof Gately. Lucy Aphramor is a Coventry-based registered dietitian who has pioneered the Health at Every Size approach, which is based on the premise that good health is best realised regardless of weight. She argues it is healthier to be a little plump than pursue weight loss through yo-yo dieting - now thought to increase inflammation, a risk factor for heart disease. "A healthy weight is the weight you stabilise at when you have a healthy relationship with food and we can't guess at that from numbers on a scale," she says. However Prof Gately warns against complacency. "You may be fine right now with a BMI of 27," he says, "but a false sense of security can lead to your weight creeping up over time - which can become a problem."