Do You Want Fries with That? An Exploration of Serving Size, Social Welfare, and Our Waistlines

Given increasing obesity rates, fingers are often pointed at “big food” and their marketing practices. Restaurant meals are indeed larger than home-cooked meals, and portion sizes have increased. We consider constrained “socially optimal”—rather than decentralized profit-maximizing—portions to see whether welfare maximizing strategies may also be waistline-increasing. We demonstrate that socially optimal restaurant meals are larger than average home-cooked meals, yet the choice to “super-size” alleviates the size discrepancy. Moreover, portion sizes at home and in restaurants increase with relative reductions in the marginal costs and/or relative increases in the fixed costs of meal preparation. (JEL I10, D11)