Once upon a time, you could only stream gaming on Twitch.
Eventually Twitch loosened the rules to allow other kinds of streaming, for example, art related streams which were not allowed before are now okay.
Stream yourself eating, however, was not allowed but as with art, the rules changed and today exist something called «Social Eating» which allow you to pig yourself in front of the camera as long as you don't eat poison and yes, this is one of the rules.
If there wasn't a valley between adult and non-adult content, I'm sure Twitch would have Social Undressing, Social Masturbation and Social Sex at this point.