Any food can cause weight gain if you eat too much of it. But certain foods are more energy dense, meaning they have more calories per gram, which makes them less filling and makes it more likely you'll overeat these foods. It's the amount of food you eat that fills you up, not the number of calories. People who consume diets that are more energy dense are more likely to be obese than those who consume diets lower in energy density, according to a study published in "Diabetes Care" in April 2007.
Fast food tends to be very high in energy density, with a typical meal containing more than twice the energy density of a healthy diet, according to a study published in "Obesity Reviews" in November 2003. Other energy-dense foods are those that are high in sugar, fat or both, such as sugar-sweetened beverages, nuts, avocados, dried fruit, full-fat dairy products, fatty cuts of meat, desserts and many baked goods.
Consume more low-energy-density foods, which are those with a high water or fiber content, including most fruits and vegetables. Fill your plate mainly with these foods and eat them first; then you'll have less room for the more energy-dense foods in your meal. You can also replace half of the amount you'd usually use of an energy-dense food with fruits or vegetables, such as using beans instead of half the meat in your favorite chili recipe.