One of the biggest problems for people trying to pare off pounds on a calorie-restricted diet is that they’ll get hungry and risk a setback. Predictably, sooner or later, they’ll eat. The solution, according to experts, is to eat healthy foods that trigger fullness.

Years ago, researchers in the biochemistry department at the University of Sydney in Australia studied common foods and scored them based on their ability to quell hunger. That rating system is called the Satiety Index (SI), which is still regarded as a valuable tool to help individuals lose weight.

Foods with a high SI score include hearty fare—appropriately prepared—such as boiled white potatoes, beans and lentils, apples and oranges, whole-grain breads and lean cuts of chicken, beef, fish and other satisfying victuals.

“You can eat an awful lot of popcorn without taking in a lot of calories,” says Susanna Holt, PhD, lead author of the landmark study. “It may not weigh much, but it makes your stomach feel full because it takes up so much space.”