@MissHavershamreturns , sorry to hear the challenge of putting on weight became unavoidable. It almost like you have to choose between two options that both are vital for surviving school/teen years. Just make you feel awfully powerless.
I do think supplements are worth a try, but it's down to each of us to decide what and how to give it a go.
On a different thought, I'm just thinking if you want to try a different brand other than Medkinet. It sounds ridiculous, as we would think there's no difference between any of these containing methylphenidate which are after all working in the same way. The release proportion might vary but the principal should be the same, hence the general effect should be similar.
But we have had a funny experience with this. Back to a months ago, I started a post talking about DS started titration with all the headache and tummy issue each time when we increased dosage. It was then compounded with mood swings (melt down every day and became withdrawn) when we got to 10mg with Medkinet. It lasted for the whole week, also with suppressed appetite and insomnia. Then we had to switch to a different brand by Day8, due to the shortage of Medkinet. The psychiatrist at the time subtly warned us that this new brand gave some kids some sort of problems than Medkinet (he didn't deliberate what it was) and asked us to watch out.
Then the interesting thing started that the day he switched to this new brand, his temper/mood swings were completely gone, his sleep improve. And when we increased the dosage to 20mg, he only had one day with headache and tummy ache, instead of the usual two miserable days when increasing with Medkinet. I still watch closely to his emotional reaction, but it appears all within normal range. By now, he's on 20mg for the second week, his appetite returned gradually from 4m onwards and he has almost no problems with sleep. (Touch wood!!!)
I'm not saying it's absolutely because we switched the brand. He did start having magnesium a few days before he switched the brand. But the psychiatrist seemed to have taken the note on board and made sure to prescribe this brand instead of Medkinet for this month, even though he couldn't provide an answer as to why there might be different. DH and I gather it's just a fact nobody knows exactly how the medicines are made and the mechanism of release (commercial secret?)
We are yet to see the effect for next level of dosage increase. I'm sure when we increased dosage further (if the psychiatrist and his dad agree to), some side effects would come back and maybe more profound, but as where we stand now, I'm more or less happy with the way things are.
However, everything is a process of trial and error, simply because each person is different Nd react to the med in different ways. There's also the possibility of med effect wanes gradually. But nobody can predict unless you are there.
Keep the options open, as there must be something that can help... Don't give up. Hugs...