It's best to do something you are motivated about so you don't lose interest. It will be a lot of work regardless of the idea.
Consumption of food is very interesting and I can see how you can approach it in a variety of ways. Maybe looking at Healthy food vs Unhealthy food, creating artwork with a strong message behind it. Maybe reflecting on how different communities consume different foods?
Since it is your 'personal' investigation, you really should think about it and what you can see yourself producing within the next few months.