Hello @macombs, Welcome to Mayo Clinic Connect. I'm sorry to say that I have the opposite problem. While we wait for other members to respond and share their experience and what they have found helpful, here are some tips on the Mayo Clinic website.

Underweight? See how to add pounds healthfully - Mayo Clinic: https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/expert-answers/underweight/faq-20058429

Have you talked to a doctor or nutritionist to see if they have some suggestions?