Video: Real-life Garfield lays claim to title of 'world's fattest cat' North Shore veterinarian Gerard Leheney said: "This is the fattest cat I have ever seen. My first reaction was astonishment. Garfield, who has already lost 1lb, is relatively healthy but finds it difficult to move because his weight is putting strain on his hips. But the shelter warned obesity in cats is extremely risky and can lead to diabetes, heart disease, joint, bone and ligament damage, high blood pressure and intolerance to heat. Now staff are encouraging Garfield to move with toys, a ball, and by picking him up and putting him down somewhere else, so he has to walk back to his original spot. Garfield will be now given over to a foster carer, while staff look for a new owner who is committed to helping him become healthy and active.