You can get similar results, at least in the short term, with most highly-restrictive diets, provided what's allowed isn't egregiously unhealthy (e.g. "eat only candy") which it almost never is.

I expect the main two mechanisms of action are that these diets tend to reduce total caloric intake (lower variety = lower interest in eating; less opportunistic snacking since what's on offer is often not allowed by the diet; and so on) and drastically reduce how much outright crap adherents eat.