both of the claims “1-2 pounds of watermelon/day kills my desire for processed desserts” and “This leads to weight loss, although maybe that also requires potatoes?” seem to me like they can be explained through the lens of volume eating. I am curious what you think of this theory of mine since you clearly have thought about it for much longer. In case you aren’t familiar with the concept of volume eating, there was a  done where they gave people 240 calories of a food to people and then measured how hungry they were over the next 2 hours and they found people who ate boiled potatoes were less hungry then people who ate 240 calories worth of anything else they tested (unfortunately boiled potatoes was also the only vegetable they tested, so who knows how it compares to other vegetables), they also found that how filling something is positively correlates with the protein, fibre, and water content of the food and negatively correlates with the fat content. watermelon has a high water content. So basically my theory is that you started eating two foods which are great for making you feel more satiated and then you didn’t crave processed desserts or other calorie dense foods anymore because you were already satiated and so you lost weight, your theories by contrast seems more complicated to me. Obviously there is a lot I don’t know about your situation (what your diet looked like before the watermelon/potatoes, your strange medical condition, etc.) but I do think it explains that part nicely, I would love to hear any evidence counter to this theory.
both of the claims “1-2 pounds of watermelon/day kills my desire for processed desserts” and “This leads to weight loss, although maybe that also requires potatoes?” seem to me like they can be explained through the lens of volume eating. I am curious what you think of this theory of mine since you clearly have thought about it for much longer. In case you aren’t familiar with the concept of volume eating, there was a  done where they gave people 240 calories of a food to people and then measured how hungry they were over the next 2 hours and they found people who ate boiled potatoes were less hungry then people who ate 240 calories worth of anything else they tested (unfortunately boiled potatoes was also the only vegetable they tested, so who knows how it compares to other vegetables), they also found that how filling something is positively correlates with the protein, fibre, and water content of the food and negatively correlates with the fat content. watermelon has a high water content. So basically my theory is that you started eating two foods which are great for making you feel more satiated and then you didn’t crave processed desserts or other calorie dense foods anymore because you were already satiated and so you lost weight, your theories by contrast seems more complicated to me. Obviously there is a lot I don’t know about your situation (what your diet looked like before the watermelon/potatoes, your strange medical condition, etc.) but I do think it explains that part nicely, I would love to hear any evidence counter to this theory.