The best way to gain weight quickly and healthily is by increasing calorie intake, perform resistance exercises and limiting cardiovascular training. A realistic goal for weight gain is 2 pounds per month, as this is approximately the limit for muscle gains in a month.
Track calorie intake by logging everything eaten and drank in a week. Increase calorie intake by 500 per day. Eat at least 150 grams of protein per day, as this is necessary for muscle growth. Healthy fat sources should encompass at least 20 percent of the diet or more if necessary. The remainder of the calories can come from healthy carbohydrate sources, such as fruits and vegetables.
To gain muscle, perform resistance training consistently. Attempt to consistently increase the weight lifted, as this builds muscle. Since cardiovascular training burns calories, limit it to three to four times per week, with each workout only taking 20 to 30 minutes. If a person leads an active lifestyle or plays sports, cardiovascular exercise may not be necessary.
Some people may gain a larger than average amount of weight during the first two weeks of increased calorie intake, as the body holds more water. Weight gain stabilizes after those first two weeks. After those first two weeks, adjust calorie intake as necessary depending on how much weight is gained or lost.