Obesity - symptom. Usually the illness is a bad diet, lack of movement, or very rarely some serious health condition. Instead of targeting obesity, fix your habits or see a doctor to see why your body accumulates excessive amounts of fat.
Dopamine issues, lack of concentration, etc. - symptoms. The illness is ADHD. By taking medicines you are targeting illness, which is correct. Targeting symptoms would be me standing behind you with a metal pipe and hitting you every time you lose focus.