Lifestyle tips

It's Cyproheptidine, a common (but old) antihistamine. It's prescription-only in the US, but here in the UK, we can buy it OTC. I've Apetamin and Tres Orix Forte (another brand, same thing) listed on Amazon Marketplace and eBay in the past.

I've experimented with it. You have to stick with it to get beyond the drowsiness (two to three days). In my experience it's very, very effective at boosting appetite.

If you can get past the sleepiness it works pretty well but it's literally the lysine that does most of the work