杨大群

Sometimes a snack quiets your growling stomach. But sometimes you just feel like munching， even though you're not really hungry. French researchers recently found that this second type of snack attack is harder on your waistline.

That's because when you eat without being hungry， blood sugar and insulin work differently than when you are hungry.

First， let's see what happens when you're hungry. Low blood sugar can trigger that hungry feeling. When you eat， your blood sugar rises， satisfying your hunger and prompting your pancreas to secrete insulin. Insulin's job is to transport sugar from the bloodstream into your body cells. Hours later， after insulin has moved enough sugar into the cells and leveled off， your blood sugar dips and you feel hungry again.

But let's say you snack before you feel hungry again. What happens to your blood sugar then？ The French study found that if people snacked without being hungry， their blood sugar stayed the same as if they hadn't snacked at all. Why？ Since the pancreas is still secreting insulin to transport blood sugar from the previous meal， it's easily stimulated to secrete a little more insulin.

People's insulin levels rose， but their blood sugar stayed the same. So， they got hungry at about their usual time， and ate just as much as when they didn't snack.

If you're like the folks in the study， snacking when you're hungry is okay. But when you're not hungry， snacking probably won't satisfy you or make you eat less later. Instead， it'll prompt you to loosen that belt a bit.

有时，吃点零食能让你的肚子不再咕咕叫。但有些时候，你只是想要吃点东西，尽管你并不饿。法国研究人员最近发现，第二种情况很容易让你发胖。

这是因为当你不饿的状态下吃东西时，血糖和胰岛素的变化与你饥饿的时候是不同的。

首先，让我们看看当你饥饿时的情况。这时，低血糖会让你产生饥饿的感觉。在你吃东西的时候，你的血糖会上升，消除你的饥饿感并促使胰脏分泌胰岛素。胰岛素的作用是把血液中的糖分运送到你的体细胞中。几小时后，当胰岛素把足够多的糖分送入细胞内并趋于稳定时，你的血糖量就会降下来，然后你又会开始感到饥饿。

让我们再来说一说当你不饿时吃零食的情况吧。你的血糖会怎样变化呢？法國研究表明，如果人们在不饿的情况下吃零食，他们的血糖会保持不变，就像自己从没吃过零食一样。为什么会这样呢？这是由于胰脏仍在分泌胰岛素来输送上一顿饭中的血糖，这时候吃零食很容易刺激胰脏分泌更多的胰岛素。

人体的胰岛素含量会上升，但是血糖浓度却保持不变。因此，人们仍然会在平常吃饭的时间感到饥饿，饭量与他们不吃零食时一样多。

如果你和研究里的人一样，在饿的时候才吃零食，那是可以的。但如果你不饿，吃零食可能不会给你饱足感或者让你随后少吃点。相反，它会让你松松裤带，吃得更多。