Eating reheated, leftover pasta and potatoes could help with weight loss, according to a nutritionist

• Eating carbs that have been cooked, cooled, and then reheated could help people lose weight.
• Reheated potatoes, rice, and pasta have more resistant starch, registered nutritionist Rhiannon Lambert explained.

Eating carbs as leftovers rather than hot and freshly cooked might help with weight loss, registered nutritionist Rhiannon Lambert told Insider.

When we eat carbohydrates, they are broken down in the gut and absorbed as sugar, which raises blood glucose levels.

However, when cooked carbs like pasta, potatoes, and rice are cooled, a type of fiber called resistant starch increases in the food, Lambert said.

"Resistant starch is the starch that resists digestion. It doesn't get digested in the small intestine and then goes on to ferment," she said.

Having a lot of resistant starch in the diet is good because it doesn't quickly convert into sugar, she said.

The resistant starch stays increased even if leftovers are reheated before being eaten, and it means that the carbs' fiber content is higher, which in turn causes fewer blood sugar spikes.

Dr. Chris van Tulleken, a researcher who has studied resistant starch, previously told the BBC that the temperature of food could help make meals more fiber friendly.

"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," he said.

Eating leftovers, even when reheated, could help with weight loss

Stable blood sugar levels aid weight management and decrease cravings caused by low energy, registered dietitian Alexandra Rowles wrote for Healthline.

And there is evidence that suggests reheated carbs can prevent blood sugar spikes.

A small 2014 study, authored by Dr. Denise Robertson from the University of Surrey and Van Tulleken, found that eating cooked, chilled, and reheated pasta caused the smallest spike in blood sugar, compared to pasta that was freshly cooked, or cooked then eaten cold.

Another small 2015 study by the University of Indonesia on white rice drew the same conclusion.

Be careful when reheating rice though — in her book "The Science of Nutrition," Lambert recommends cooling and refrigerating within an hour of cooking, reheating thoroughly, and eating within a day to prevent bacterial spores from forming.

Eating more resistant starch could also increase feelings of fullness and satiety, according to a 2015 study.

To boost the resistant starch in bread, Lambert recommends freezing slices and toasting straight from frozen.

"If people are on a body fat loss mission and they're looking at leveling their blood sugar levels, or if they're looking at their productivity and avoiding afternoon slumps, it could be beneficial to try and consume more resistant starch," she said.