“Typically, one to two pounds per week is the maximum amount of weight gain indicated,” says Dr. Kroll. “Rapid weight gain can put excessive stress on the cardiovascular system, leading to cardiac output problems.”
“This can cause blood pressure issues, fluid buildup in the lungs and lower limbs, and can also be toxic to the liver,” he adds. “Also, rapid weight gain can cause increases in adipose tissue.”
Before gaining weight, it’s best to check with your doctor, adds Mary Wirtz, registered dietitian, certified specialist in sports dietetics, and consultant for Fit Healthy Momma.
“Each individual is really very different in terms of appropriate weight gain goals, and weight gain recommendations depend on a number of factors, including age, physical activity level, medical history, medications, and more,” says Wirtz.
Atkinson adds that if it’s difficult for you to gain weight, you might want to “consider going just above a healthy body fat percentage.” [the percent of total body weight that is composed of body fat in proportion to lean mass, organs, tissues and water]because when you go back into maintenance mode, you will likely lose some body fat naturally.
Increase your calorie intake
Gaining weight requires a caloric surplus, and that means eating more calories than you burn each day, says Atkinson. Experts also suggest that gaining lean body mass generally requires a protein intake of at least 1.5 to 2.2 grams per kilogram of body weight per day.
Because every underweight individual has different nutritional needs, Atkinson also recommends going to a doctor who can evaluate CBC results to check for vitamin B or iron deficiencies.
“Underweight patients often have individual B vitamin deficiencies, such as low levels of thiamine, folate, and cyanocobalamin,” says Dr. Kroll. “They also have low levels of iron and can have resultant anemia.”
If you discover that you have nutritional deficiencies, you and your doctor can discuss whether it might be beneficial for you to start taking a supplement.
How many extra calories do you need to gain weight?
Aim to add 300 to 500 calories per day above your maintenance caloric intake to gain weight in a slow, healthy way, advise Dr. Kroll and Wirtz.
Slowly increasing calories allows the body to adjust to caloric demand and thus provide the energy needed for safe weight gain, says Chiariello, but the quality of those calories is still important. “Processed foods that are high in fat and calories are not a healthy choice and can lead to unwanted fat gain,” she says.
Focus on a healthy diet
For healthy weight gain, focus on healthy foods, says Chiariello. These include:
- Whole grains, such as oats and quinoa, which provide essential vitamins, minerals, carbohydrates and fiber.
- fresh fruits and vegetables, such as spinach, broccoli and apples, which provide essential vitamins, minerals and fiber.
- lean protein, like chicken and fish, which provide amino acids for muscle development.
- unsaturated fats such as olive oil and avocado, which are excellent for heart health.
- Adequate fluid intakespecifically water, necessary for hydration and intestinal regularity.
Overloading on unhealthy fats and sugars isn’t a good idea, even when trying to gain weight, as these food groups can lead to health problems, including high blood pressure and diabetes. “Fried foods, with added sugar and/or salt or without nutritional density should be limited”, says Chiariello. “Reading food labels is valuable and also provides information about ingredients.”
Throughout the weight gain process, be sure to monitor your cholesterol and lipid profile with regular blood tests to ensure your levels are healthy, says Atkinson. He also advises using a glucometer to check your fasting blood sugar level to make sure it’s not too high.
Increase your protein intake
To build muscle mass, people need about 2 grams of protein per pound of body weight, says Atkinson. “So if we were to calculate that for someone who weighs 170 pounds, or 77 kilograms, they would consume 108 to 154 grams of protein per day,” he says.
Additionally, high-protein diets have been shown to promote muscle mass, prevent muscle loss, and decrease the amount of muscle lost with aging, says Oluseun Olufade, MD, an athletic physician who works with several professional sports organizations and teams, including Emory. University, Atlanta Hawks and US Soccer. “Protein can be consumed every three to five hours to help maintain muscle mass,” he says. “Foods that contain 10 grams of protein include 40 grams of skinless cooked chicken, 50 grams of canned tuna, 120 grams of tofu, 60 grams of nuts and 40 grams of cooked lean beef, pork or lamb.”
To increase your protein intake, consider adding animal protein sources such as poultry, fish, red meat, eggs, Greek yogurt and cottage cheese, plant sources such as beans and lentils, nuts, seeds, tofu, whole grains and, in smaller amounts, fruits and vegetables, says Wirtz. Protein powders, shakes and bars are also easy sources of protein on the go.
A healthcare professional can help you assess the correct amount of protein you need to gain weight based on your body type and needs.