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UW Professor Explores Obesity Epidemic in Research Paper

May 13, 2014
Woman smiling
Anna Zajacova, an associate professor of sociology, co-wrote a study on obesity that was published online in the American Journal of Preventive Medicine. (UW Photo)

A University of Wyoming professor contributed to a study that found persons who are obese early in life have a higher chance of being severely obese later in life. However, losing pounds at any age can lower the risks associated with being overweight.

Anna Zajacova, an associate professor in the Department of Sociology, co-wrote a study titled “Long-term Obesity and Cardiovascular, Inflammatory and Metabolic Risk in U.S. Adults,” that was posted May 6 in the online version of the American Journal of Preventive Medicine. The article will appear in the publication’s June print edition.

The study found that people who were obese by age 25 had a higher chance of more severe obesity later in life.

“It is a combination of whatever behavioral, genetic and environmental influences resulted in that obesity in early adulthood is not going to radically change,” Zajacova says. “One’s weight is a product of these complex influences for a number of years. Research is trying to understand how long-term body weight affects health.”

Zajacova wrote the paper with Jennifer Dowd, an associate professor of epidemiology and biostatistics at the City University of New York (CUNY) School of Public Health, Hunter College.

The two reviewed data of adults (ages 35-64) from the 1999-2010 U.S. National Health and Nutrition Examination Survey. They learned that men who were obese at age 25 had a 23.1 percent estimated chance of class III obesity (defined as a Body Mass Index, or BMI, greater than 40) after age 35. By contrast, men of a normal weight at age 25 had only a 1.1 percent chance of severe obesity after age 35.

The statistics were even more dramatic for women. The chances of class III obesity after age 35 jump to 46.9 percent if they are obese at age 25. For those at a normal weight at age 25, the chances of class III obesity at age 35 drop to 4.8 percent.

Those who become morbidly obese at 35 or later are more susceptible to high blood pressure, high cholesterol, diabetes, hypertension, inflammation and other chronic conditions. Additionally, obesity creates wear and tear on body tissue and joints, and excess weight around the stomach releases pro-inflammatory hormones.

Zajacova stresses that obesity is much more complicated than people not getting enough exercise. She surmised that genetics, changes in the food industry (lower fat but higher-carbohydrate foods); people eating larger portions; and environmental factors, such as hormone disrupters in plastics and pollutants, all can be possible causes.

“It’s (obesity epidemic) certainly more complex than eating more and moving less,” she says.

Zajacova said that, in population-level data, there were very few examples of adults -- ages 35-64 -- losing significant weight and keeping it off. In the elderly, loss of weight was due primarily to Illness or gradual loss of muscle mass with old age, she says.

According to the study, the most recent 2009-2010 estimates show 35.9 percent of American adults aged 20 years or older are categorized as obese. That number has risen dramatically from 13.3 percent in 1960-1962. The probability of being obese at age 25 has increased by 30 percent for those persons born between 1955 and 1975.

On the positive side, present weight, rather than the duration of obesity, was a much better indicator of cardiovascular and metabolic risk. Regardless of how long a person has been overweight, this means that losing weight at any stage of life may help reduce adverse risks.

“Duration of obesity may still have important implications for mobility and musculoskeletal disease, research questions that should be investigated,” Zajacova says. “Prevention of weight gain at all ages should, thus, be a clinical and public health priority.

“The cumulative effects of long-term obesity may be less important than people’s weight at a given time point,” she continues. “That’s good news because it means that the cumulative effects of obesity on health may be less pronounced than we thought. So, if people can restrict their body weight, their obesity earlier in life may not matter as much.”

The American Journal of Preventive Medicine publishes articles about the primary and secondary prevention of important clinical, behavioral and public health issues such as injury and violence, infectious disease, women’s health, smoking and sedentary behaviors, physical activity, nutrition, diabetes, obesity, and alcohol and drug use.


Hear researcher Anna Zajacova summarize her research on obesity published in the American Journal of Preventive Medicine.Hear researcher Anna Zajacova summarize her research on obesity published in the American Journal of Preventive Medicine.

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