My doctor told me a couple crackers is enough. All you need to do is eat enough to line your stomach to keep your stomach from absorbing it too fast. Can also be to protect your stomach. Some medications eat away at your stomach lining so eating with food can help. Ibuprofen is one example.
No there are no thickening products that fix hair loss. Monoxadil and other similar products work but you can never stop using them or your hair will fall out again.