Brandeis Magazine

If you’re overweight, you may be at greater risk for stress-related diseases like Type 2 diabetes, cardiovascular disease and cancer. If that’s not worrying enough, new research in psychologist Nicolas Rohleder’s lab suggests overweight and obese people carry more unhealthy baggage than healthy-weight people, in the form of higher levels of stress-induced inflammation linked to chronic and life-threatening maladies.

Rohleder studies the health effects of the stress hormone cortisol, which is involved in the inflammatory response. Although normal inflammation is an important part of healing, runaway inflammation can contribute to chronic and life-threatening diseases. “We know that overweight and obese individuals already have chronic low-grade inflammation,” says Rohleder. “Now it seems that when you add stress to the mix, it’s a double hit.” 

Over the course of two psychological stress tests, Rohleder and his team measured levels of the stress-related inflammatory-agent interleukin-6 (IL-6) in healthy-weight and overweight individuals. Weight classifications were based on several factors, including body mass index (BMI) and body-fat percentage. Individuals with a BMI of 25 or higher were classified as overweight. 

On the first day of testing, lean and overweight individuals reacted similarly to stress, despite higher starting levels of IL-6 in overweight participants. On the second day of testing, however, the IL-6 levels of overweight participants nearly doubled, while the IL-6 levels of lean participants responded in the same way as on the first day.

Rohleder says the relationship between BMI and IL-6 levels is linear — even among lean individuals, the higher the BMI, the higher the IL-6. “Every percentage point of body fat seems to make you more susceptible to inflammation,” he says.  

With two-thirds of Americans classified as overweight and worldwide obesity rates doubling since 1980, understanding the health risks of excess weight could not be more important.