Both obese and underweight patients are more than twice as likely to develop depression as people at a healthy weight, researchers in Australia found.
They said unhealthy weight should act as a trigger for opportunistic screening of depression in general practice.
Their study asked 3,361 adult patients at 12 Australian general practices to provide their height and weight and complete a PHQ-9.
Over 20% of adults had a BMI >30 and were classified as obese, and 2.6% were underweight with a BMI of <18.5.
A total of 23% of obese patients and 24% of underweight patients had depression. In contrast, prevalence of depression was 11% among normal-weight patients and 12% in overweight patients.
Factors linked to obesity, such as stigmatisation and low self-esteem, can lead to depression. In turn, depression symptoms such as weight gain and physical inactivity can then exacerbate problems with unhealthy weight, researchers said.
Yet, despite the common co-occurrence of depression and unhealthy weight, there are no models for providing combined treatment, researchers said.
They said: 'In conclusion, weight and depression demonstrated a U-shaped relationship, with higher prevalence of depression observed among underweight and obese general practice patients.
‘These conditions may act as red flags for opportunistic screening in the general practice setting.’