Stress Increases Weight Gain by Slowing Metabolism Study Suggests
Stress influences a person’s metabolism, causing it to slow down and therefore influencing weight gain, according to the results of a recent study. Linking stress to weight gain is not a new theory, but understanding just how a person’s mental state can affect the way that they physically process foods is an area that until just recently has not been thoroughly understood.
An earlier study, published in the Journal of Affective Disorders, concluded that people with a history of depression presented with a higher level of body fat, a heavier body weight and a larger waist circumference than those who did not have a lifelong depressive disorder. The study published this week was designed to look deeper into the metabolic processes and how they are effected by stress and depression.
The study, published in Biological Psychiatry, used 58 healthy women subjects. These women were given a meal to eat each day. On day one, the women received a meal high in saturated fat. On day two they were given a meal high in oleic sunflower oil. In the days leading up to the study, all of the women were given balanced meals to eat. The researchers were looking to explore the impact that day-to-day stressors and a history of some kind of major depressive disorder had on the individual metabolic response to different types of fat.
The women were given a test designed to measure the amount of stress that they had been under the day before. A source stress could have been an argument with a partner, trouble at work, children being naughty or an unexpected event which caused them to feel upset. The researchers also tested their basic metabolic rate at rest, so that they could tell how many calories each women burned per day. The first meal that the women were given consisted of foods that were high in saturated fats, such as sausage with gravy or eggs and biscuits. In total, the first meal contained 60 grams of fat and 930 calories. The second test meal was the same in terms of calories and fat, but more unsaturated fat instead of saturated fat.
Each day, after they had eaten their test meal, the women were given metabolic tests so that the researchers could record how many calories they were burning as they digested. These tests were given every hour for seven hours after eating. Alongside the metabolic tests the researchers also recorded the levels of cholesterol, glucose, insulin and the stress-related hormone known as cortisol.
The women who recorded higher levels of stress showed a slower rate of metabolism,burning both calories and fat at a lower rate than the less-stressed women did. Janice Kiecolt-Glaser, study author, explained that it is this slowing in metabolism that leads to weight gain as a result of high levels of stress.
Women who reported one major form of stress the day prior to the study appeared to burn 104 calories less in the meal that they ate when compared to women who did not report any stress. If this is a single isolated occurrence the results would be minimal, however, if this happened every day it could result in a weight gain of 11 pounds over the course of a year.
The results also indicated that the women who were under greater levels of stress burned fat at a slower rate and had higher levels of insulin. Both of these factors put these women at an increased risk of weight gain, obesity and diabetes.
The researchers did not find any significant differences between the types of fat that were eaten pertaining to metabolism. Both types of meal, regardless of the levels of saturated fat and unsaturated fat, were affected equally by the stress that the women eating them was under. This result somewhat undermines the conception that saturated fat leads to more weight gan and other negative effects that unsaturated fat does. In fact, is suggests that it is not the saturated fat that is the problem , but the level of stress that the person eating it is under.
It has to be pointed out that there are a number of limitations to this study, the sample size is small, only 58 women were tested, and of these, 38 of the women were breast cancer survivors, so it is not an ideal population to use when making generalizations to the total population. The study did not look at how metabolism was effected by low-fat meals, nor did it use any male participants.
For all these reasons, caution should be taken before the results of this study can be used to form any general conclusions. However, the speculative conclusion is that stress has the undesirable effect of increasing weight gain and slowing metabolism. Yet it is another study suggesting that stress is not good for health. Despite the limitations that this study has presented, the advice to lower levels of stress should be considered a recommendation worth consideration by all.
By Tabitha Farrar