Animal use in medical research is widely accepted on the basis that it may help to save human lives and improve their quality of life. Recently, however, objections have been made specifically to the use of animals in scientific investigation of human obesity. This paper discusses two arguments for the view that this form of animal use, unlike some other forms of animal-based medical research, cannot be defended. The first argument leans heavily on the notion that people themselves are responsible for developing obesity and so-called ‘lifestyle’ diseases; the second involves the claim that animal studies of obesity's causes and therapies distract attention from preventive efforts. Drawing on both empirical data and moral reasoning, we argue that the relevant attributions of responsibility and claims about distraction are not plausible, and that, therefore, there is no reason to single out the use of animals in obesity research as especially problematic.