Depression Linked to Metabolic Health Regardless of Body Mass Index

Results published in PLoS One show an association between poor metabolic health and depression, regardless of weight status.¹

Although obesity is often associated with metabolic syndrome (characterized by elevated blood glucose, blood pressure, and cholesterol, for example), some obese individuals do not have these abnormalities, and thus are considered to have a metabolically healthy obese (MHO) phenotype. Obesity has also been linked to an elevated risk for depression, although other studies found no such connection.^2,3 Some findings suggest an independent association between metabolic syndrome and depression, regardless of obesity status.⁴

Few studies have examined the link between depression and the MHO phenotype. The current authors noted that such findings could help elucidate the relationship between depression and obesity. To that end, they investigated this association in participants with or without cardiometabolic abnormalities during a 16-year follow-up period. They prospectively analyzed data from an epidemiological French study that began in 1989.

Assessment of body mass index was based on participants’ self-reported height and weight. Metabolic status was based on self-reported medical diagnosis or treatment for hypertension, hypercholesterolemia, or type 2 diabetes between 1990 and 1996. Adjustment was made for covariates such as marital status, sex, age, alcohol intake, and physical activity. The Center for Epidemiologic Studies Depression scale was used to assess depressive symptoms at multiple points throughout the follow-up period.

Of the 14,475 adult participants (75% male), 57.0% were metabolically healthy and 6.2% were obese. Among the obese participants, 33.0% were metabolically heathy. Compared with metabolically unhealthy obese individuals, the MHO participants were younger and had higher socioeconomic status and moderate alcohol intake.

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Compared with metabolically healthy normal weight individuals, a higher risk for depression was found at the start of follow-up in those with metabolically unhealthy normal weight (odds ratio [OR], 1.37; 95% CI, 1.25-1.51), overweight (OR, 1.44; 95% CI, 1.31-1.59), and obesity (OR, 1.30; 95% CI, 1.10-1.54), but not in MHO participants (OR, 1.04; 95% CI, 0.81-1.32). Over time, depressive symptoms decreased in all groups, but this reduction was less pronounced among metabolically unhealthy obese participants.

Taken together, these results demonstrate that “metabolic health status rather than obesity predicted depressive symptoms at the start of follow-up, whereas obesity predicted a poorer course of depressive symptoms over time in metabolically unhealthy individuals only,” the authors concluded.