A survey by researchers at the University of California, Davis, concluded that there is no necessary link between being overweight and having a high risk of death. During the six-year follow-up period, overweight or obese people did not have a higher risk of death than normal-weight people. As for the severely obese, they faced a higher risk of death only if they also had diabetes or high blood pressure. The report, published July 18 in the Journal of the American Board of Family Medicine, calls into question the previous study. Previous studies (data collected at a time when obesity was not very common) linked high short-term mortality to weight gain. Many people believe that any degree of overweight and obesity increases the risk of death, but our new findings are very different from that notion,” said researcher Anthony Jerant, a professor in the Department of Family and Community Medicine at the University of California, Davis. Over the past six years of investigation, we found that only those who were particularly severely obese had a greater risk of mortality, but only if they had diabetes and high blood pressure.” Based on this study, Gillant recommends that doctors tell overweight or obese people that obesity is harmful to physical and mental health, but does not increase the short-term risk of death. Instead, doctors should warn severely obese people with diabetes or hypertension that the condition increases short-term mortality, and also suggest appropriate treatment measures, such as weight loss. Gillant mentioned that “being overweight or obese is not without any threat to personal or public health, and in order not to have a serious impact on quality of life, we also recommend obese people to lose weight.” In carrying out the study, Gillant collected nationwide data from 2000 to 2005. Nearly 51,000 adults, ranging in age from 18 to 90, participated in the Medical Expenditure Panel Survey (MEPS), a fixed sample survey on health care utilization and health care costs. The survey data also included information on health status, such as the presence of diabetes and high blood pressure. The study ultimately classified the population as being on the light side (BMI 35). During the six-year follow-up, nearly 3 percent of the 50,994 people, or 1,683 people, died. The researchers found that the risk of mortality among the severely obese was 1.26 times higher than that of normal-weight people. But if they did not suffer from diabetes and hypertension, then those who were overweight, obese or even severely obese had a mortality rate similar to or lower than that of normal-weight people. Those who are underweight, whether or not they have diabetes or hypertension, have about twice the mortality rate of those who are normal weight, which is consistent with earlier studies. Overweight and obesity have become increasingly common in recent decades. Nearly one-third of adults over the age of 20 in the United States are obese, and another third are overweight. In addition to diabetes and high blood pressure, problems associated with obesity include heart disease, osteoarthritis and sleep apnea. The link between body weight and mortality has long been controversial. Although some analyses of data from 30 years ago have shown that mortality risk increases with weight, recent data (including the current study) have raised significant questions about this assumption. Our study suggests that the risk associated with a higher-than-normal BMI in modern people may be lower than before, but the reason for this is not certain, Gillant said. It is likely that as the number of overweight and obese people has increased, doctors have become more aware of the resulting complications, such as high blood pressure, high cholesterol and high blood sugar, so that they can be detected early and treated. The six-year duration of the survey is not enough to show the link between unhealthy weight and long-term mortality risk. But hopefully this study will stimulate more research to revisit the relationship between being overweight or obese and long-term mortality.