So, the minute one has an ADHD diagnosis.. or heck, practically any diagnosis of anything, they'll get some 'helpful' suggestions of things they can do to change their diet, with the strong implication that they will be 'cured' by this one weird food, or by stopping eating anything they enjoy.
And so I'm hesitant to talk too much about how diet has impacted my ADHD.
But I'm gonna do it anyway, and remind people one more time here:
Different bodies need different things! What works for me may not work for you, and that's ok. That's good actually! Try different things, see what works for you. I'm sharing this as things people may try if they want to, because I have had success with it.
Several years ago, I decided to cut 'junk food' out of my life, which was a bit difficult to define, and what I have and haven't eaten since that point has shifted several times. Right now, I have a couple of key things I follow.
1.) I'm a vegetarian. I still eat eggs, dairy products, and honey, but I've stopped consuming meat. This isn't so much about beliefs (though there's a lot of good reasons to abstain from meat in our current world) but about the fact that I feel good when that's what I eat. I can't even really explain in exactly what way I feel better, just that I do.
2.) I try to eliminate sugarcane sugar from my diet, in fact I try to minimize all refined sugars in my diet. This one I always feel weird about bringing up in the context of ADHD, because far too many people will say that it causes ADHD in kids, that kids are just having a 'sugar high' to explain the impusivity and hyperactivity of kids with ADHD or some such nonsense. So I'm going to say here and now, there's no evidence that sugar of any kind causes ADHD. I have found, for me, that after I consume sugarcane sugar I do feel fuzzy-headed and, depending on how much I consume, it can make me feel 'off' for up to a few days. So, since I don't like that feeling, I don't eat it anymore. I have found it fascinating to see how much my sense of taste has changed since I cut it out, and I have a better sense of when I'm thirsty now than I used to.
3.) I do not limit my caloric intake. As an acrobat I work out a lot and I need calories to fuel my body. My struggles with executive function make choosing what to eat and actually eating it difficult in the first place, I don't put more restrictions on doing so.
I have found that any food related 'rule' I set for myself, I have to treat as an absolute. Being an absolutist about things limits the strain on my executive funtion. The rule is already in place, it doesn't have to be evaluated per interaction. I'm not weighing out merits each time, I just check "does it follow my rules?" or not. I don't have foods that are 'not allowed' in my home.
I also have a hard time recognizing what I'm hungry for or that I'm hungry before I am suddenly hungry and no longer very functional. I have a physical list of go-to snack foods and go-to meals that can be made quickly. So, when I'm hungry, or when I realize that it's time for more food, I frequently consult that list. Even if something I choose is just "good enough", at least I'm fed.
I also have the extremely good fortune to have people in my home who love to cook, and have similar dietary restrictions. So, I do a lot of dishes, and I appreciate being fed. I realize that I am soo very lucky in that, as feeding myself is actually something that is very hard for me. I have managed some meal planning to feed myself in the past, but it's been years since I've had to.