Changing and tracking diet long-term is nigh impossible. Has there been any work that you know of using economic incentives as a proxy? i.e. test group is grant

Changing and tracking diet long-term is nigh impossible. Has there been any work that you know of using economic incentives as a proxy? i.e. test group is granted coupons good for fruits and vegetables, while control group is granted fully discretionary coupons Obviously it's an imperfect experiment, but it seems like a pragmatic compromise.