I haven't seen any studies that imply that fasting increases or decreases metabolic rates, which would mean that most people probably won't implicitly gain or lose significant amounts of weight just by switching to intermittent fasting.

There are people that literally just start skipping breakfast while keeping lunch/dinner/snacking the same. This is both technically intermittent fasting but also a reduction in overall caloric consumption. These people sometimes attribute their newfound weightloss to IF, when really they just started skipping a calorically dense meal every day.