My personal experience is that there's a direct correlation between my physical health and effectiveness of my ADHD medication.
My hypothesis is that since it's about my brain capability to register and prioritise stimuli, the busier said brain is (with other body issues) the less likely it is too perform executive functions. This might be the general case, but since we start from the unfavorable position, it might be more debilitating for us.
(I've no idea why I'm using such a fancy language rn. Apologies)