Good comments. Contradicting current research is always a red flag.

The paper does not dispute that children with obesity are more likely to be diagnosed with depression, though. That correlation is clear. The conclusion seemed to focus more on the causation aspect, suggesting that underlying environmental factors influence both mental health issues and obesity in a population. From the editor's notes:

> the study finds that previous estimates of the effect of BMI on childhood emotional and behavioural symptoms may have been overestimated due to confounding with the environment. Larger samples will be needed to determine whether there is a causal effect of BMI on childhood emotional or behavioural problems, and what size it is.