Your parents knew that leftovers were economical. Your foodie friends know that leftovers sometimes taste better than they did the day before. But now there's yet another reason to love that day-old pasta living in your Tupperware: It may be less fattening than freshly made.
Testing out a theory about how pasta affects blood-glucose levels in people, a BBC show called Trust Me, I'm a Doctor conducted a test to see whether a sudden intake of carbohydrates like pasta would make body chemistry act differently depending on how cool it was. The show gathered a group of volunteers and, over several days, fed them hot, freshly cooked pasta with a garlic-tomato sauce; the same pasta and sauce after it had spent the night in the fridge; and, finally, the pasta and sauce again, but reheated from the fridge. They then had their blood glucose tested.
The thinking was that the leftovers might trick the body into thinking they're healthier than they are. The simple sugars from easily processed carbs like hot pasta, potatoes, and cake cause a rise in the body's blood-glucose levels, which the body naturally reacts to with an influx of insulin to bring the blood glucose levels down again swiftly. That peak and sudden drop has a tendency to make you hungry again, because even though your blood glucose is at its normal levels, you're experiencing a relative downturn compared to what it was just a few minutes ago, and want more sugar to achieve those highs again.
Because hot pasta that's been cooled forms "resistant starches" that make them harder to break down into simple sugars (meaning fewer calories), the show wanted to test to see whether leftover pasta would indeed result in less of that drastic up and down in blood sugars that could be so dietarily disastrous. And the show did, in fact, find that there was less of a spike and drop in people who ate cold leftover pasta.
But the really interesting thing was that it found that the people who ate the reheated leftover pasta had the least significant blood-glucose spike of all—a whopping 50 percent less than the spike experienced by those who ate the freshly made stuff.
A University of Surrey scientist is going to continue the leftovers study with funding from Diabetes U.K.
"It's something that could simply and easily improve health," Dr. Chris van Tulleken, who coordinated the experiment for the show, told the BBC. "We can convert a carb-loaded meal into a more healthy fiber-loaded one instead without changing a single ingredient, just the temperature. In other words, our leftovers could be healthier for us than the original meal."