Severe Obesity in Middle Age Linked to BMI at age 25

New research published in the American Journal of Preventive Medicine reveals that a person's risk of developing severe obesity later in life is linked to whether they are obese at age 25.

A team of researchers led by Jennifer Dowd, and associate professor of epidemiology and biostatistics, City University of New York (CUNY) School of Public Health, examined the relationship between BMI at age 25, obesity later in life and biological indicators for health.

Obesity rates have increased in the US over the last several decades, with the latest data from the Centers for Disease Control and Prevention indicating that 35 percent of adults over the age of 20 are obese.

The researchers found that most people who were obese at age 25 were more likely to be severely obese later in life. However, the team found that a person's current weight, rather than the duration of their obesity, is a better indicator of overall cardiovascular health and metabolic risk.

Obese women, it turns out, are more likely than men to become severely obese after age 25. Using data collected from the 1999-2010 US National Health and Nutrition Examination Survey (NHANES), the researchers found that women who were obese at age 25 were 47 percent more likely to reach Class III obesity (defined as BMI greater than 40) later in life, compared to just 5 percent of women who were a normal weight at age 25.

For obese men at age 25 there was a 23 percent chance that they would develop Class III obesity later in life, compared to a 1 percent chance for men of normal weight at age 25.

This news may sound grim for individuals trying to lose weight, the study authors said. But they also learned that a person's current weight is more strongly linked to overall cardiovascular and metabolic health than the duration of obesity, meaning that losing weight at any stage may help reduce heath risks, regardless of how long a person has been overweight.

"The current findings suggest that the biological risks of longer-term obesity are primarily due to the risk of more severe obesity later in life among those obese early in life, rather than the impact of long-term obesity per se," Dowd said in a statement. "This is good news in some respects, as overweight and obese young adults who can prevent additional weight gain can expect their biological risk factors to be no worse than those who reach the same level of BMI later in life."

"This study adds to growing evidence that in terms of traditional cardiovascular, inflammatory, and metabolic risk, obesity duration confers little additional risk beyond the current level of attained weight," Dowd continued. "The bad news, in turn, is that maintaining a stable level of obesity from a young age is not the norm, and being obese at age 25 years places individuals at risk of a much more severe level of obesity later in life compared to those who are normal weight at age 25 years."