Some foods that cause a person to gain weight quickly are nuts, bagels, dried fruit and avocados. Calorie-dense, nutritious foods are the healthiest choice for weight gain. Foods that are high in sugar, such as cake and candy, cause weight gain, but are unhealthy.
Calorie-dense foods, such as nuts, have more calories in a single serving than most other foods. An ounce of walnuts has 175 calories, and 2 tablespoons of peanut butter has 188 calories. Nuts are not only calorie-dense, they are also convenient; they have a long shelf life and are easy to carry. Peanuts add calories to a trail-mix, and almond slices enhance the texture and nutritional value of breakfast cereal.
One of the most calorie-dense types of bread is bagels. A single bagel provides about 330 calories. A whole-grain bagel is an enjoyable and healthy breakfast option. Spreading peanut butter or low-fat cream cheese on a bagel provides protein and additional calories.
Another way to add calories to food is to add healthy sources of fat. Fat has more calories per gram than carbohydrates or protein, and it is more healthy than refined carbohydrates, such as corn syrup. Avocados are a high-fat fruit with about 368 calories per cup. They are a healthy and calorie-dense ingredient that add calories to sandwiches, tacos and many other dishes.