oooppps btw, congrats to him for the clean time, well done cause its really hard to acomplish :)
you mean fast food like junk food ? because its good he is starting to eat again, this is the good thing. the bad thing is the quality of the food he is eating.. :(
if you or him are the ones cooking that would be much better , muuuuch better :) But i'm afraid he has to avoid junk food, macdonalds and etc, because this food is full of the worst fat and empty calories and there are no many good stuff in them to be absorbed. you should try to make him eat proteins ( meat, fish, eggs ...veggies ) without a lot of fat, no fries and stuff like this. instead try to cook him pasta, macaroni, salads, rice, fruit natural juices ......its better eating five times a day and this is the type of food he should be eating now so that he would feel much better about everything .
the thing with fast food or sweets is that they give a sort of energy shoot and they do the trick to our bodies and mind but this energy is very short term so it last very little and they mess with our glucose levels this way, so he will have some cravings for more junk food as soon as the energy fades away, it is like a vicious circle concerning food that we have to break ...and it could happen that those glucose cravings ( cravings for junk food) could be taken by cravings by his mind and start craving for his doc...red alert then , you know what i mean ? exercising would be great for him now, even some walks wiill be good ..
as for the vitamins, try to find a good mineral+vitamin complex ( better in gel capsules) , a B's complex to take in the mornings, ok ?
if i can help u in any way, pls, tell me, right ?
there are delicious recipes with healthy food .. :)