Christine McInnis, a current graduate student at Brandeis University, recently authored a paper about a study she conducted on the relationship between stress and obesity. It was published in “Brain, Behavior, and Immunity,” which is the official journal of the Psychoneuroimmunology Research Society (PNIRS). McInnis is in her third year in Brandeis’s Department of Neuroscience and has been working on this study since May 2013. She was interested in the relationship between obesity and inflammation, and was drawn to this study because she liked the research that was being done on actual people.

The overall focus of the lab is on stress and how being overweight may exacerbate it. Particularly, McInnis was wondering, “If we expose you to the same stressor two days in a row, are you any less stressed out on the second day?” The stressor they used in this study was called the “Trier Social Stress Test.” Participants would enter a small room for a “job interview” where two people from the laboratory dressed in white lab coats would be sitting at a table, with a camera behind them, facing the participants. They would be instructed to give a five-minute speech about their personality and what made them good for this job. Before the participants began, however, they would be told that the people conducting the interview were trained to evaluate them, watching their body language and various other evaluative aspects to make the participant feel very judged and intimidated. During the participants’ speeches the “interviewers” were not allowed to smile, nod or give the participants any sign of approval. After the participants finished, they would be asked to count backward from a number by increments of another number. After the test, the participants remain there for about two hours, so as to measure their bodies’ response to the stressor over time. The participants would then be subjected to the same test the following day, and the results from both days are collected and studied.
The study proved that there is, indeed, a relationship between stress and being overweight. McInnis focused on the body’s level of Interleukin 6 (IL-6), which is secreted by T cells and macrophages to stimulate an immune response. She discovered that on the second day, the IL-6 increase for leaner people was the same magnitude as the first day, but more overweight and obese people had responses that were twice as large on the second day (as compared to the first day). The main finding was that the latter group had an exaggerated response to repeated exposure to the stressor, as a result of having more body fat. The excess fat stimulates the immune system in a damaging way, which heightens inflammatory levels and causes many diseases such as diabetes and atherosclerosis. Adding stress to that situation makes it even more dangerous.

McInnis hopes that people pay attention to this study and realize that being overweight and being stressed are interrelated and can have very harmful results.

All of the research was done on the Brandeis campus. McInnis stated that she enjoyed working with Professor Nicholas Rohleder (PSYC), the leading investigator of this study. “He’s very straightforward and relatable,” said McInnis. “He listens to me; if I come up with an idea, and it’s based in science and affordable he says, ‘OK, sure’!”

Rohleder’s main goal for this study was “to understand how stress can make people sick, or how lifelong stress can reduce overall lifespan, or healthy lifespan.” In addition to what McInnis focused on, other points tested by Rohleder’s team are more psychological (for example how people tend to reflect or show self-compassion). “This study and the results are so great because they show how psychological factors like being stressed interact with a biomedical factor (how much fat do you store in your body) to lead to an unhealthy outcome,” said Rohleder.
Having completed this study, McInnis still has many questions, and is eagerly looking forward to finding the answers. However, for stressed college students, she has one piece of advice: “Exercise, absolutely exercise!” Not only does exercise relieve stress, it also helps improve the body’s immune system. It amends all bodily systems that get disrupted.