Firstly, the medical profession doesn’t know much about ADHD, especially in adults, or females of any age (as evidenced by the huge delay in diagnosis and treatment in the UK right now).
Secondly, if you give some kids Ultra Processed food, or non-diet cola, they definitely go a bit “hyper”. I’ve witnessed this many times - and also seen some nasty reactions to those drinks that don’t have sugar, but are sweetened with aspartame and other artificial sweeteners.
Thirdly, Joe Wicks does have a degree in Sports Science. Quite a lot of a Sports Science degree is study of the effect of various foods on the body, so I don’t agree with the PP’s who have suggested (snarkily) that he doesn’t know what he’s talking about.
With recent studies on UPF’s showing that it’s more harmful than previously believed, he’s probably on the right track on this point.