Consider Nutrient Content. Many high-calorie foods that can help you gain weight quickly are unhealthy. Examples include high-sugar foods, such as cake, pie and candy, and foods high in saturated fat, such as full-fat cheese, butter, sour cream and fatty meats.Choose nutrient-dense sources of calories to stay healthy as you gain weight.aining weight requires you to consume more calories more than you expend. Knowing which foods are high-calorie can help you meet your goals for calorie consumption and rapid weight gain.