... sugar would furnish the extra energy needed to walk a mile; a quarter of a pound represents about one-sixth of a man's daily fuel requirement. But one baked potato would furnish the same energy as the three lumps of sugar; a quarter of a pound of cornstarch would supply the same fuel as the quarter pound of sugar. Nutritionally starch and sugar are interchangeable, the advantage as far as digestion is concerned being with the starch rather than the sugar. And yet we ... — Everyday Foods in War Time • Mary Swartz Rose