Fat and healthy? Study finds slim isn't always superior

Published in the journal Applied Physiology, Nutrition and Metabolism, the study finds that obese people who are otherwise healthy live just as long as their slim counterparts, and are less likely to die of cardiovascular causes.

"Our findings challenge the idea that all obese individuals need to lose weight," says lead author Jennifer Kuk, assistant professor in York's School of Kinesiology & Health Science, Faculty of Health. "Moreover, it's possible that trying -- and failing -- to lose weight may be more detrimental than simply staying at an elevated body weight and engaging in a healthy lifestyle that includes physical activity and a balanced diet with plenty of fruits and vegetables," she says.

Kuk's team looked at 6,000 obese Americans over a 16-year span, comparing their mortality risk with that of lean individuals.

They found that obese individuals who had no (or only mild) physical, psychological or physiological impairments had a higher body weight in early adulthood, were happier with this higher body weight, and had attempted to lose weight less frequently during their lives. However, these individuals were also more likely to be physically active and consume a healthy diet.

Researchers used a newly-developed grading tool, the Edmonton Obesity Staging System (EOSS), which has been found to be more accurate than body mass index (BMI) for identifying who should attempt to lose weight. Developed by University of Alberta researchers, it is modelled on staging systems that classify the extent and severity of other diseases such as cancer, mental illness and heart disease. It offers five stages of obesity based on both traditional physical measurements such as BMI and waist-to-hip ratio, plus clinical measurements that reflect medical conditions often caused or aggravated by obesity (such as diabetes, hypertension and heart disease).

Kuk stresses that in order to determine whether or not they should lose weight, individuals should see a physician to be evaluated using the EOSS criteria.

The study is co-authored by Chris Ardern, Assistant Professor, York University; Timothy S. Church, Director of the Laboratory of Preventive Medicine, Pennington Biomedical Research Center; Arya M. Sharma, Professor of Medicine & Chair in Obesity Research and Management at the University of Alberta, and Scientific Director of the Canadian Obesity Network; Raj Padwal, Associate Professor, University of Alberta; Xuemei Sui, Assistant Professor, University of South Carolina; and Steven N. Blair, Professor, University of South Carolina.