The discoveries about glucose help explain why dieting is a uniquely difficult test of self-control — and why even people with phenomenally strong willpower in the rest of their lives can have such a hard time losing weight. They start out the day with virtuous intentions, resisting croissants at breakfast and dessert at lunch, but each act of resistance further lowers their willpower. As their willpower weakens late in the day, they need to replenish it. But to resupply that energy, they need to give the body glucose. They’re trapped in a nutritional catch-22:
1. In order not to eat, a dieter needs willpower.
2. In order to have willpower, a dieter needs to eat.
As the body uses up glucose, it looks for a quick way to replenish the fuel, leading to a craving for sugar. After performing a lab task requiring self-control, people tend to eat more candy but not other kinds of snacks, like salty, fatty potato chips. The mere expectation of having to exert self-control makes people hunger for sweets. A similar effect helps explain why many women yearn for chocolate and other sugary treats just before menstruation: their bodies are seeking a quick replacement as glucose levels fluctuate. A sugar-filled snack or drink will provide a quick improvement in self-control (that’s why it’s convenient to use in experiments), but it’s just a temporary solution. The problem is that what we identify as sugar doesn’t help as much over the course of the day as the steadier supply of glucose we would get from eating proteins and other more nutritious foods."
By John Tierney/ NYTimes.com/read more
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