Acontroversial new government study have have shaken some dieters' resolutions to lose weight.
The research showed that people who are moderately heavy, up to 30 or so pounds above normal, have a slightly lower risk (6%) of premature death than those at a normal weight.
But those who are extremely obese -- roughly 60 or more pounds over a normal weight -- have a 29% greater risk of dying early, according to the review of 97 studies by researchers at the National Center for Health Statistics, part of the Centers for Disease Control and Prevention. The scientists examined deaths from all reasons compared with people's body mass index (BMI), a number that considers weight and height.
The research, which received widespread news coverage, is causing some to think that their extra weight may not be the danger they thought it was. Are such reactions justified?
USA TODAY turned to two experts for answers: Thomas Frieden, director of the CDC, and Walter Willett, chairman of the nutrition department at the Harvard School of Public Health.
Q: Do you think being a few pounds to 30 pounds over a normal weight is hazardous?
Frieden: Yes, I think that increased weight carries a number of health risks, but not all weight is the same. If you work out and build muscle mass, you may increase weight, and that's healthy. The study that came out was about death rates. It didn't cover type 2 diabetes and other health risks, which we know increase with weight.
Willett: The hazards of being a few pounds overweight partly depend on how someone got there. If someone has always been muscular and is active and strong, and their blood pressure and levels of (blood) glucose and cholesterol are fine, then their health risks are probably minimal. However, if someone has gotten to this weight by putting on 10 pounds or more, has increased their waistline by more than 2 inches, or has elevations in blood pressure, glucose or cholesterol, then this weight can be a serious health risk.
Q: Should people try to lose weight if they are overweight?
Frieden: The key is to do things that you can stick with. Find physical activities you love doing, and do more of them -- whether that's walking or sports or playing with your kids or dancing. Being physically active is very important at any weight. Similarly, find healthy foods that you love and eat more of them and less of unhealthy things.
Willett: The large majority of overweight people have gotten there because they have added weight as adults, and almost all will have some metabolic abnormalities (such as high blood pressure) because of this. Thus, most people who are overweight will benefit from some weight loss, even if it is only a 5% loss.
Q: Why would the research show that those who are overweight are at a slightly lower risk of early death?
Frieden: The science on this is complicated. There are two big unknowns. The first is what is the right method to study the relationship between body mass index and death rates. The second is whether BMI is the best measure. We know that BMI is an imperfect measure. Things like waist circumference and skin-fold thickness may be more accurate for some types of analysis. But BMI is easy to use in large epidemiological studies.
Willett: The most serious problem in the paper is that the normal-weight group included a mix of lean and active people, heavy smokers, patients with cancer (and) other conditions that cause weight loss, and frail elderly people who had lost weight due to rapidly declining health. Because the overweight and obese groups were compared to this mix of healthy and ill persons who have a very high risk of death, this led to the false conclusions that being overweight is beneficial and that grade 1 (moderate) obesity carries no extra risk.
The new statistics are completely misleading for anyone interested in knowing about their optimal weight. The paper is a pile of rubbish.
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