Alpaca, I just happen to have a feeding tube for life and have gone through 4 different formulas since April and have spent countless hours chasing nausea and heart burn. I am using a Kangaroo Joey but mostly because I consume a lot of water and 65+ syringes a day didn't sound like fun.

If your friend consumed the same amount of formula as used when the weight gain occurs, more weight will be gained. When I use the pump for feeding, it takes me almost an entire can extra a day to keep the weight on. The nausea needs to be isolated, if possible. Almost everything I see is an overload of bile/stomach acid. When the stomach is not full, I have bubbling mucus from my stomach and if I don't do something in a day or two, it turns to hydrochloric acid that I can taste. Also, the stomach continually pulls on the bulb as if it is trying to digest the tube. When fuller, none of that happens. I used baking soda to break the cycle and have only needed it a handful of times so far which is good as it can cause an increase in blood pressure over time if used too often.

I started looking into all the ingredients and especially the method of calorie boosting being added. Some use sugars, others use fats and then there are some with carbs. Each method has some nuances that cause other issues. One uses fructooligosaccharides which are sugars from fruit and vegetable sources like onions, garlic, bananas, agave, artichokes, asparagus, leeks, etc. In some people these sugars pull helpful bacteria through the digestive system beyond where they would normally be found. Salmonella is one. Probiotics, as Christine suggested, would help with that. I make yogurt every week and use whey.

The transport agents for fat delivery is also a culprit. Everyone is trying to find the magic that works for everyone. Unfortunately, the body is hard to fool. Comfort can only be found with a lot of work and experimenting. All the obvious questions have been asked except possible GERD issues, sitting or laying down while feeding, feeding too late at night, not ingesting enough water throughout the day, adding meds to an empty stomach, not getting enough restorative sleep, for example.

Another thing I am curious is if there were already nausea issues and that is what led up to not eating as much. It sounds like it.

I was told about a study that found as high as 25% of people that don't have our swallowing issues aspirate saliva while they sleep at night. Having too little water during the day will thicken the sinus mucus and cause a concentration of bacteria that can end up in the lungs but if not, in the stomach.

Those are some things I have looked at.