What does "cleanse" mean here? Does it refer to going on a diet?
To "cleanse" something means to make it clean and free of any toxins or impurities. So in this case, you are right, going on a "cleanse" is similar to going on a diet. However, a diet is mostly used to imply that someone is trying to lose weight while a "cleanse" just refers to a period of time where someone tries to get rid of the toxins in their body by eating only healthy foods and drinks. Sometimes this is done by only consuming water or other liquids. In the case of the video here, the bears go on a cleanse where they eat only bear food and no human food. Ex: I'm starting a juice cleanse tomorrow. Ex: Lately I've been eating a lot of unhealthy food but now I want to go on a cleanse.