A Physicians Committee study tested a plant-based diet in a group of 64 women. At the start of the study, all of the women were moderately or severely overweight. Participants followed two simple rules: They set aside all animal products and kept oils to a minimum. They lost 13 pounds, on average, in 14 weeks, without calorie counting or exercise. A year later, they’d maintained an 11-pound weight loss. After two years, they were still below their original weight.

Plant-based diets can help you lose weight and keep it off because they are packed with fiber, which helps fill you up, without adding extra calories. Aim for 40 grams of fiber a day, which is easy to do when you move vegetables, fruits, whole grains, and beans to the center of your plate.

By skipping meat, cheese, and eggs and limiting oils, you’re also removing a significant amount of fat from your diet. This helps keep the pounds off, because 1 gram of fat—from beef, fish, or oil—has 9 calories. Compare that to 1 gram of carbohydrate from potatoes, bread, or beans, which has only 4 calories—fewer than half of the calories found in 1 gram of fat.