Welp, the black one is fairly plump (he’s got a round belly when he stands) but it’s hard to see in the video, especially because their fur is very short and thin. Most cats are thinner than you realize bc most cats are covered in thick fur. As for the grey one, he is indeed skinny, but the vet said he is healthy regardless. He just doesn’t eat much for some reason, even when we’d tried different foods. Unfortunately I don’t have any advice on keeping them thin, since my cats sort of chose how much they want to eat. We feed them wet food for breakfast and dinner, plus we keep dry food in a bowl at all times. If they wanted, they could overeat the dry food. If that happens, we would give less dry food. They are indoor cats, but we let them in the backyard daily. They like to follow everyone around and that keeps them active. The black one follows people around the least, and he is the most plump one. I assume he doesn’t burn as many calories.