Your main problem in trying to develop a thesis statement is that your subject is so broad. Normally a thesis sets forth a position to be argued about a narrow topic but you haven't really identified a manageable subject area or type of stance.
One area you could discuss is the ethics of food. For example, you might argue for a thesis that as research increasing shows that animals can feel pain and experience something akin to what we consider emotions, that it becomes unethical to treat animals as things to be used rather than as individuals with basic rights to whom we have moral obligations.
Another possible ethical approach would be a thesis arguing that we should pay attention to the total carbon impact of the foods we consume and avoid foods which are raised using unsustainable practices. For a paper on this thesis, you could include discussion of the carbon footprints of different cooking methods.
Another possible thesis would argue that how we prepare our foods has a major impact on our health and go on to discuss the health consequences of different food preparation methods.