A recent study by Desai et al.
1 of 54 obese adolescents found that 50 percent of the sample showed some type of psychopathology, usually Major Depressive Disorder (MDD). Other studies have shown that those with MDD are 1.5 times more likely to be obese.
2 Of note, MDD is associated with obesity (BMI>30) and not overweight (BMI=25-29.9). Overweight is sometimes a risk factor for depressive symptoms, but not clinical depression.
3
Depressed people are more likely to be obese; obese people are more likely to be depressed. Which came first? Does obesity cause depression? Does depression cause obesity? Are they simply correlated?
It turns out that all of the above may be true in different people.
Part 1: Obesity Causes Depression
Research has shown that obesity causes depression in a few different ways. First, overeating and lack of exercise can simply make people feel bad. An article published in Eating Behavior4 describes a four-week intervention in which college students were instructed eat double their normal amount of calories and take a maximum of 5000 steps per day. All other exercise was prohibited. Not surprisingly, the students gained weight during the study. The students also scored much higher on depression inventories four weeks after embarking on a new gluttonous lifestyle.
Another, far more mysterious possibility exists for how obesity may cause depression. We once thought that our fat mass was just there, clinging to our bodies, ready to supply energy if needed, but mostly causing our clothes to fit a little too snug. We now know that our fat mass, or adipose tissue, is a living, functioning, hormone-producing part of the endocrine system. Fat secretes hormones called adipokines, including leptin, resistin, and adionectin. Obesity increases levels of leptin and resistin and decreases levels of adionectin. According to a metaanalysis by Taylor and MacQueen5, the fluctuation of these hormones is a plausible link between obesity and depression.
Part 2: Depression Causes Obesity
Depression's causal link to obesity is not as strong as obesity's causal link to depression. A study by Jansen et al.6 found that a subset of the population will use food to control negative emotions or depression. This study looked at overweight/obese and normal weight participants, and then clustered them into high and low negative affect subtypes. Researchers then induced a negative mood and put out tasty treats. The triggers (negative mood induction and tasty treats) elicited overeating only in the overweight/obese high-negative affect subtype. Overweight participants with a more positive affect did not eat more after the negative mood induction. Normal weight people did not change their eating behavior based on mood. Researchers found that obese/overweight subjects with a high negative affect were more likely than their cohorts with a low negative affect to worry about their appearance.
Part 3: Depression and Obesity are Correlated without Causation
Twin studies have shown that, after controlling for all other confounders, those who are depressed are likely to be obese, and vice versa. This points to an undiscovered common gene that is responsible for both depression and obesity.7
Applying the Correlation Between Depression and Obesity to Job Corps
Strategy #1: Keep recreation schedules on your desk and encourage students to exercise. Exercise is the strongest predictor of weight loss, not only because it burns calories, but because it elevates mood, self-efficacy, and self-concept. In fact, in a study by Annesi8, only 19 percent of a subject's weight loss in an exercise intervention could be directly attributed to calorie expenditure. There was a direct correlation between weight loss and mood score.
Strategy #2: Use resources from the
Foods and Moods Curriculum to work with students who eat to control negative emotions and body-related worrying.
Strategy #3: View the
Binge Eating Disorder tip sheet for information on working with students with binge eating disorder.
Strategy #4: Cognitive therapy is successful in preventing weight regain. Consider using cognitive therapy in a group setting.
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Sources
1 Desai, R.A., Manley, M., Desai, M.M., & Potenza, M.N. (2009). Gender differences in the association between body mass index and psychopathology. CNS Spectrum. 14(7), 372-83.
2 De Wit, L.M., Fokkema, M., van Straten, A., Lamers, F., Cuilpers, P., & Pennix, B.W. (2010). Depressive and anxiety disorders and the association with obesity, physical, and social activities. Depression and Anxiety. Epub ahead of print.
3 Boutelle, K.N., Hannan, P., Fulkerson, J.A., Crow, S.J., Stice, E. (2010). Obesity as a prospective predictor of depression in adolescent females. Health Psychology. 29(3)293-298.
4 Emersson, A., et al. (2010). An obesity provoking behaviour negatively influences young normal weight subjects' health related quality of life and causes depressive symptoms. Eating Behavior. 11(4), 247-252.
5 Taylor, V.H. & MacQueen, G.M. (2010). The role of adipokines in understanding the associations between obesity and depression. Journal of Obesity. 2010; 1-6.
6 Jansen, A., Vanreyten, A., van Balvern, T., Roefs, A., Nederkoorn, C., Havermans, R. (2008). Negative affect and cue-induced overeating in non-eating disordered obesity. Appetite. 51(3); 556-562.
7 Afari, N. et al. (2010). Depression and obesity: do shared genes explain the relationship? Depression and Anxiety. 27(9), 799-806.
8 Aneesi, J.J. (2008). Relations of mood with body mass index changes in severely obese women enrolled in a supported physical activity treatment. Obesity Facts. 1(2)88-92.
