It probably has something to do with your brain being more relaxed. Like I remember seeing somewhere being a “life hack” to chew gum when you are anxious because your brain then goes, oh, I’m eating, that means I must be safe enough to eat and not worry about my surroundings. From personal experience, food plays a part in stuttering. When I’m counting calories and therefore eating less, I tend to stutter more. When I eat and for some time right after, I stutter less. So if I’m having a bit of a lousy day for stuttering, then I’ll chew some gum to tone it down a notch if I’m between meals.