We’ve long been told that too much stress is bad for our health. Living under the burden of stress for extended periods of time can increase your blood pressure, worsen coronary artery disease and lead to heart rate irregularities, not to mention the psychological toll it takes. While the exact ways stress influences your physical health aren’t all completely known, hormones that coordinate how your body responds to stressful situations are likely involved. A new study has now revealed that how much you weigh may influence how high those hormones go.

The researchers looked at a hormone called interleukin-6 (IL-6) that is often circulating in the blood during periods of stress. They set out to determine if a person’s weight would influence the levels of this hormone in the blood at times of stress. To study this, they brought in a mix of overweight and normal-weight individuals classified both by BMI and body fat percentage. They then subjected them to stressful situations over the course of several days.

At the outset, overweight individuals had a higher baseline of IL-6 and stress hormone cortisol, which is consistent with previous findings that increased body fat is responsible for increased baseline inflammation. After the first day of stress, IL-6 rose about the same amount in both the lean and overweight groups. On the second day, the overweight individuals saw their IL-6 levels almost double from the prior day, while normal-weight individuals held steady at initial levels. The researchers found that the level of inflammation in response to stress was linear, meaning that as BMI and body fat percentage rose, inflammation also rose, even in individuals who were normal weight.

The research provides some insight into why increased body fat may predispose a person to more disease. The results indicate that as fat increases, a person is more prone to inflammation, both on a baseline level and in the context of stressful situations. The researchers point out that it’s unclear where this increase in stress hormones is coming from.

An important implication from the study is that lowering body fat even by small amounts may help reduce overall inflammation in your body, which in turn has positive health effects. This goes along with prior research indicating that losing even small amounts of weight can decrease your risk of diabetes, heart disease and can lower your blood pressure.

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