Excerpt from ‘The Case for Keto’ by Gary Taubes
Hunger and the switch
We have to live with two realities: that fat cells are exquisitely sensitive to insulin, and that this is a threshold effect. The two together have profound consequences for how different foods will affect not just weight but appetites — our hunger and the foods we crave. Those consequences, in turn, speak directly to the question of whether a drastic, supposedly “unbalanced” diet that removes an entire food category may be necessary.
As I suggested earlier, think of this fat-cell, insulin-sensitivity threshold as a switch that’s either on or off. When it’s on, above the threshold, your fat cells are storing fat; the rest of your body is fueling itself on carbohydrates. When the switch is off, when insulin is below the threshold, your fat cells are mobilizing fat; you’re burning fat for fuel; you’re getting leaner or at least not getting fatter.
If you’re insulin resistant, these dynamics still hold true. But now you have more insulin circulating through your body than is ideal, and the amount of insulin will remain high for longer than ideal. This means you’ll spend that much more time above the threshold, with the switch on, storing fat. It’s likely this will be the case even long after you’ve eaten, after blood sugar levels have returned to normal and you might not have carbohydrates (glucose) readily available to burn. Your cells will be primed to burn carbohydrates—that’s what the insulin is telling them to do—but blood sugar will already be in the low range of healthy. And while the insulin is instructing the mitochondria in your cells to burn carbs, it’s actually pushing those same cells, through the same signaling pathway (as it’s technically known), not to burn fat and not to burn protein. Elsewhere, the insulin is causing the fat cells to hold on to fat and the lean cells to hold on to their protein.In short, when insulin is above the threshold, when the switch is on, your body is running on carbohydrates. They are your fuel. So it makes sense that you’ll hunger for carbohydrate-rich foods.
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