Why texture changes appetite
Appetite is not only willpower. The body reads food through texture, volume, chewing, stomach stretch, digestion speed, and signals from the gut. Fibre can influence several of those inputs because it holds water, adds structure, and can build viscosity.
That does not mean fibre is an appetite suppressant in a simplistic way. A thick shake, a high-fibre meal, a bowl of dal, and a whole fruit all create different experiences. Some slow eating. Some add body. Some increase stomach stretch. The useful idea is practical: food that has structure often feels more complete than food that disappears quickly. That structure is part of the signal.