PhD defence E.S. (Eline) van der Valk

Brief summary:

We investigated the relation between obesity, stresshormones and the immune system.  To do this, we measured stresshormones in scalp hair, which gives an average of the past weeks-months. First, we gathered all measurements of stress hormone in scalp hair worldwide. We demonstrated that people who had higher stress hormone levels tended to be heavier and have a larger waist circumference. 

In addition, we found that people with more stress hormones often became even heavier in the future. They also more often developed cardiovascular diseases, particularly in people under the age of 60. In this group, the effect of stress hormones on the risk of heart disease was similar to other risk factors such as high blood pressure or diabetes. 
Additionally, we saw that the immune system of people with high stress hormones is often chronically active. This means the immune system doesn’t only activate when someone is sick, but stays active all the time. This may contribute to the health problems of people living with obesity. 

We also looked at whether the immune system can recover if people receive support for lifestyle changes, such as healthier nutrition, more exercise and receiving psychological guidance. After 1.5 years, the immune system of these people improved partially. In summary, obesity appears to affects the functioning of the stress system and immune system. We believe that treatments focused on improving these systems could help people with obesity to become healthier.