The gut biome is self reinforcing. If you eat nothing but sugar (simplified example) the bacteria that thrive will be the ones that most resourcefully consume sugar. Other strains will wither away entirely or to a very insignificant state. Some, like yeast, actually kills 95% of the colony and the other 5% eat it, so it can take years to bring under control in people with immunocompromise (autoimmune disease, AIDS). If you eat nothing but fibrous vegetables (another simplified example) then your biome will be very different. And part of what makes you hungry is the nutrients the bacteria in your gut desire in order to maintain the colony. So you eat the right foods, then your body desires the right foods. You can re-program your biome to an extent by eating differently. And that goes for eating good or bad food. So I suspect (but cannot prove) that this is where the effect comes from.