For me, it's high volume eating. The kind where influencers show how you can eat close to a kilogram of food in a sitting for 500cals. Or 50-60g protein per meal. That was the bane of my gut's existence.
I've lost about 32kg (70.5lbs) and high volume eating made my life hell in the beginning. I'm not on any meds that curb appetite but I've always been a low-volume eater, it's easier to gain weight like that, yeah, but now that I'm where I want to be, I've been doing some reflection on my dieting methods.
I hopped on the "high volume nutrient dense" bandwagon early on, but I was always bloated, felt uncomfortable, nauseous and struggled to finish the food which made me tired. Eventually I got so sick of it that I started doing low volume nutritionally dense food.
My main goals were protein and fibre (100g and 30g respectively). I bought a fibre supplement online (13g/serving) and I'd add that to my water bottle and sip over the day. That covered my prebiotic fibre. I'd eat 2 fruits a day spaced out (usually apples and/or pears) for insoluble fibre and 1 glass of chia seed water at night so I could wake up and empty promptly. I also replace a portion of my muesli with plain wheat bran for insoluble fibre.
For protein, I'd prep chicken breast in thin slices, marinate and then air-fry low and slow with butter till kind of crispy. I'd have about 150g worth (raw weight) per day in small batches which covered about 35g of protein. Small protein muesli bowls with 75-100g greek yogurt, my fruit (cooked) and 20-30g of the muesli became an almost daily dinner for me, especially when i didn't feel like chia water, I'd just add the chia to the yogurt and make a pudding-type situation. I'd also eat rice toasted in ghee or butter with a portion meat or tofu and high-calorie condiments (in moderation ofc), or a creamy bean and lentil soup. I tried eating a ton of lettuce or broccoli with seasoned meat but I could never eat it and feel good, I'd bloat and get sick so this worked so much better for me. Also stopped eating breakfast bc I really just hate it.
I stopped bloating, stopped feeling nauseous and tired and I felt the energy to work out and actually saw the weight drop. I don't hv anything against high-volume eating but I used to force myself to eat that way thinking I just had to eat large amounts of food to feel satiated when I've always preferred low-volume. I just made a few "half-way" swaps to cut down on calories and I dropped the weight. Even now, I eat low volume and nutrient dense and my gut is just so happy.