Oct 31, 2014

Leftovers Lite

While not usually nine days old, some foods taste better the second time than when first cooked. Many people say leftover pasta tastes great. Now an experiment has shown that it also might be better for us.

Pasta is a form of carbohydrate and like all carbohydrates it gets broken down in our gut and then absorbed as simple sugars, which in turn makes your blood glucose quickly rise. In response to a surge in blood glucose our bodies produce a rush of insulin to get our blood glucose back down to normal as swiftly as possible, because persistently high levels of glucose in the blood are extremely unhealthy.

A rapid rise in blood glucose, followed by a rapid fall, can often make a person feel hungry again quite soon after a meal. It is true of sugary sweets and cakes and also true for things like pasta, potatoes, white rice, and white bread. That is why dieticians emphasize the importance of eating foods that are rich in fiber, as these foods produce a much more gradual rise and fall in blood sugars.

Cooking pasta and then cooling it down changes the structure of the pasta, turning it into something that is called 'resistant starch'. It is called that because once pasta, potatoes or other starchy food is cooked and cooled it becomes resistant to the normal enzymes that break carbohydrates down and release glucose that causes a blood sugar surge.

According to Dr. Denise Robertson, from the University of Surrey, if you cook and cool pasta down then your body will treat it much more like fiber, creating a smaller glucose peak. You will also absorb fewer calories.

A study was conducted and volunteers had three days of testing, spread out over several weeks. On each occasion they had to eat pasta on an empty stomach. The volunteers were randomized to eating either hot, cold, or reheated pasta on different days.

On one day they ate the pasta, freshly cooked and hot with a plain sauce of tomatoes and garlic. On another day they had to eat it cold with the same sauce, but after it had been chilled overnight. On a third day they ate the pasta with sauce after it had been chilled and then reheated.

On each of the days they also gave blood samples every 15 minutes for two hours, to see what happened to their blood glucose as the pasta was slowly digested. Eating cold pasta led to a smaller spike in blood glucose and insulin than eating freshly boiled pasta.

Cooking, cooling, and then reheating the pasta had an even smaller effect on blood glucose. It reduced the rise in blood glucose by 50%.

We can convert a carb-loaded meal into a more healthy fiber-loaded one without changing a single ingredient, just the temperature. Leftovers could be healthier than the original meal.