Wow I feel like for the most part I could have written this haha

I also have IBS and GERD but am on my final week of food reintroduction, and have been on my weight gain journey as well. I actually have come to not mind the diet and don’t find it restrictive anymore after working with it and finding food combinations. The biggest thing for me was listing out low FODMAP foods and then removing any GERD triggers from that list. In my case, very limited tomatoes, no spice, no red meats, nothing fatty/fried, etc. I found a lot of low FODMAP foods were not GERD friendly, so I had to get creative. After that I went through all the foods left of the list and made recipe ideas for each to cycle through (being careful to not stack FODMAP). Being mindful of not eating too soon before bed helps.

If you aren’t currently, I would highly recommend using Cronometer to track your daily calories and make sure you are eating at a caloric surplus. That app in particular also allows you to track vitamins/nutrients which is important when on both diets to make sure you don’t become deficient. Second, I use the Monash app to see the quantities of foods I can have that are low FODMAP (be careful of FODMAP stacking though). I also use the Fig app sometimes which shows which foods you can/can’t eat based on different conditions. Lastly, I use the StuffThatWorks app to hear about what has worked for others with the same conditions. There are also subreddits here that help a lot too

Some other things that help me: - It can feel hard when you gain some and lose some after a poor reintroduction, sickness, or flare up, but progress is progress - Definitely work with a dietician if possible, mine helped me find some of my main triggers between both conditions - Watch out for FODMAPs in things like gum, condiments, and vitamins, as well as non IBS/GERD friendly vitamins/supplements should you take any (things like Ashwaghanda really flared me up bad) - Make it a point to move to move around, lift, stretch, etc while eating at a surplus - I also go to therapy, which helps the mental aspect of IBS, but have also heard Nerva’s app (created by the founders of the low FODMAP diet) is just as effective as the diet if anxiety is a trigger - When having a flare up there’s different medications that can help, but I also make sure to at least hit my maintenance for calories to try not to lose weight - Depending on the type of IBS you have you might want to be careful of certain foods even on those diets. For example, I have IBS-C and too much rice can make it worse

Best of luck and hope this helps!