Foods to gain weight quickly and safely People who need to gain weight can often do this by increasing their intake of foods rich in whole carbohydrates, healthy fats, and protein. Like include whole grains, dried fruit, potatoes, avocados, oily fish, eggs, and dairy products. A doctor may recommend that people with a low body weight try to gain weight. According to the Centers for Disease Control and Prevention (CDC) , about 1.6% of people aged 20 years and older in the United States are underweight. The most sustainable way to gain weight is to do so slowly. Methods of rapid weight gain may be hard to maintain. People who wish to gain weight quickly should speak with a doctor first. In some cases, difficulty gaining weight or unexplained weight loss can signal a serious underlying health condition that needs medical treatment. What exercise make you gain weight ? Exercises that help you gain weight include squats, pushups, pull-ups, deadlifts and many other s...