Think back to last year when a provocative study found that being overweight - but not obese - may help you live longer. It certainly wasn't the first bit of research to challenge the conventional medical view of the ideal body weight. These reports, which got big play in the contrarian news media, helped fuel the appealing notion you can be fat and fit.
But people who now consider themselves to be pleasantly plump should brace for a reality check.
A major study, published this week in the New England Journal of Medicine, concludes that those extra pounds do, in fact, take a toll on your health.
Overweight adults were 13 per cent more likely to die during the period of study than their less heavy counterparts, according to the research team, which included U.S. government scientists at the National Cancer Institute as well as collaborators from a dozen major research centres worldwide.
To reach their conclusions, the researchers analyzed 19 long-term studies that involved a total of 1.5 million participants. They relied on the body-mass index, or BMI - the most commonly used measure for body fat - as the basis for comparing people. (BMI is calculated by dividing your weight in kilograms by the square of your height in metres.)
A BMI between 25 and 29.5 is considered to be overweight and a BMI exceeding 30 is obese.
With these BMI figures in mind, the researchers then looked to see who died during the various study periods, which ranged from five to 28 years.
Over all, they found the healthiest BMI is between 20 and 24.9. That suggests a BMI of 25 or greater tips the scale to the unhealthy side.
Being too thin isn't ideal either. A BMI of less than 20 was linked to an increased risk of death from all causes.
"Smoking and pre-existing illness or disease are strongly associated with the risk of death and with obesity," said the lead U.S. researcher, Amy Berrington de Gonzalez. "A paramount aspect of the study was our ability to minimize the impact of these factors by excluding those participants from the analysis."
This new study represents one of the largest efforts to assess the effects of body weight on health and may help dispel the confusion created by the contradictory results from some of the earlier trials.
Still, no study is perfect. A big drawback to this latest work is that the vast majority of the 1.5 million subjects were Caucasian. Additional research is under way to determine if the results hold true for other groups.
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