You forgot to eat. For seven hours. Now you're shaking and furious and need food immediately. 

You weren't busy. You just didn't notice. ADHD affects interoception - your brain's ability to register signals from your body. Hunger, thirst, needing the bathroom - the messages get lost. By the time they break through, you're already in crisis mode. You're not bad at self-care. Your alert system is delayed.

If you'd like the scientific wording for this, let me know.