What are the causes of the relationship between obesity and autism?

The relationship between obesity and autism is complex and influenced by multiple factors. Biologically, people with autism may have alterations in the regulation of their circadian rhythm and in hormones such as melatonin, cortisol, and leptin, which affect appetite and metabolism, contributing to weight gain. In addition, some medications used to treat autism have increased appetite as a side effect.

There are also behavioral and social factors. Sensory hypersensitivity, common in autism, can lead to highly selective eating, favoring ultra-processed and nutrient-poor foods. Low physical activity due to motor difficulties or a preference for sedentary activities, along with sleep disturbances, also contributes to the risk of obesity.