FOR those of us who would like to shed a few pounds, dietary advice usually boils down to brute arithmetic. Reduce energy input by eating less, and increase energy output by exercising more. Simple. Except that as anyone who has tried it knows, it isn't.
One reason is that our evolutionary history has given us a powerful drive to eat rich foods when they are available. Now that they are virtually ubiquitous, resisting temptation can be an endless losing battle.
But there's more to it than that. Treating food as simple units of energy – 100 calories in a chocolate-chip cookie, 1 calorie in a celery stick – may make diets easier to understand, but it is a recipe for failure. Food contains a lot more than just energy. It is stocked with powerful molecules that change how your metabolism works. The odds of meeting the infuriating demands of a ...
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