Risk of future depression in people who are obese but metabolically healthy: the English longitudinal study of ageing.

There is some evidence to suggest that obesity is a risk factor for the development of depression, although this is not a universal finding. This discordance might be ascribed to the existence of a 'healthy obese phenotype'--that is, obesity in the absence of the associated burden of cardiometabolic risk factors. We examined whether the association of obesity with depressive symptoms is dependent on the individual's metabolic health. Participants were 3851 men and women (aged 63.0±8.9 years, 45.1% men) from the English Longitudinal Study of Ageing, a prospective study of community dwelling older adults. Obesity was defined as body mass index ≥30 kg m(-2). Based on blood pressure, high-density lipoprotein cholesterol, triglycerides, glycated haemoglobin and C-reactive protein, participants were classified as 'metabolically healthy' (0 or 1 metabolic abnormality) or 'unhealthy' (≥2 metabolic abnormalities). Depressive symptoms were assessed at baseline and at 2 years follow-up using the 8-item Centre of Epidemiological Studies Depression (CES-D) scale. Obesity prevalence was 27.5%, but 34.3% of this group was categorized as metabolically healthy at baseline. Relative to non-obese healthy participants, after adjustment for baseline CES-D score and other covariates, the metabolically unhealthy obese participants had elevated risk of depressive symptoms at follow-up (odds ratio (OR)=1.50; 95% confidence interval (CI), 1.05-2.15), although the metabolically healthy obese did not (OR=1.38; 95% CI, 0.88-2.17). The association between obesity and risk of depressive symptoms appears to be partly dependent on metabolic health, although further work is required to confirm these findings.