bmi body mass index illustration
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First, Make Sure You’re Underweight

Your body mass index (BMI) is a measure of your body fat. It uses your weight, height, and age to give you a healthy range. In general, if your BMI is less than 18.5, you’re underweight. Talk with your doctor about what your weight should be and how you can safely reach your goals. 

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six panel healthy meals
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Eat More Often

If you eat five or six smaller meals a day instead of three big ones, you may be able to get more calories in, and that can help you gain weight. This is especially true if you don’t have much of an appetite or you get full quickly, which can lead to your being underweight.

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pouring glass of milk
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Drink Your Calories

Instead of beverages like diet sodas, coffee, and tea, reach for milk, juice, or a smoothie with full-fat dairy and fresh fruit or vegetables. They’ll give you calories and nutrition those other drinks don’t have. 

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bowl of potato chips
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Stay Away From Junk Food

Too many “empty” calories with added salt, sugar, and unhealthy fats can be bad for you, no matter what you weigh. Nutritious foods like fruit, dairy, meat, beans, and certain vegetables can help you gain weight in a more healthy way.

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mango potato salmon triptych
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Choose the Right Healthy Foods

Not all fruits and vegetables are low in calories. Take dense fruits like mangoes or avocadoes, for example, or starchy vegetables like potatoes and corn. And fatty fish, like salmon, is a great way to get healthy protein into your diet.

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loaded baked potato soup
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Top Your Soups

Think bacon bits, sour cream, yogurt, cheese, and even powdered milk: They can add calories as well as flavor. Not only will you get more per bite, you might like it so much that you eat more, too.

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avocado and quinoa salad
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Dress Up Your Salads

Don’t drop nutrition-rich foods like salads from the menu just because you think they’re low in calories. You can pump them up with healthy fats like olive oil and add-ons like avocado, cheese, nuts, and seeds. Or try fruit like apples, pears, and berries for a little zip.  

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grilled cheese sandwich close up
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Be Cheesy

It’s rich in calories, has vitamins and nutrients your body needs, and is good on burgers, sandwiches, potatoes, eggs, casseroles, and lots of other things. Just watch the saturated fat, which can add up and cause health problems if you have too much.

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celery and peanut butter
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Go Nuts With Snacks

Nuts, peanut butter, almond butter, and other nut butters are a great way to pack in nutritious calories. If you like carrot sticks and celery stalks, dip them in a nut butter or cream cheese first. Dried fruit and seeds also make good calorie-rich snacks.

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woman writing in food journal
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Keep Track

Old habits are hard to shake, and it can be tough to remember everything you eat from day to day. A food journal can show you areas you might need to work on and help your dietitian make sure you’re getting the right nutrients.

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woman pouring smoothie with timer
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Drink at the Right Time

If you have something to drink right before a meal, you might be less hungry. It may be better to sip on something high in calories while you eat or wait 30 minutes afterward to have a beverage. Try different approaches, and keep track of them in your food journal.

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man lifting hand weight in gym
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Exercise to Build Muscle

This includes yoga, push-ups, pull-ups, weight training, and other activities that can help you add weight. They do burn calories, but that can make you hungrier so you eat more. Talk to your doctor about the best way to exercise for weight gain, especially if you have health conditions that make it hard for you.

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hand cutting white chocolate cheese cake
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Indulge Once in a While

They lack nutrition, but pies, cakes, and cookies can add extra calories. Just don’t overdo it. And remember that you can satisfy a sweet tooth with some foods that have nutrients and calories, too. Yogurt, fruit, and granola are good choices.

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smoked trout fillet
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Know Your Fats

It’s a great source of calories, but not all fat is created equal. Look for “good” polyunsaturated and monounsaturated fats, like the ones in trout, salmon, avocados, walnuts, and olive, safflower, and canola oils. Stay away from trans fat. It's bad for your heart.

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Sources | Medically Reviewed on 1/3/2018 1 Reviewed by Melinda Ratini, DO, MS on January 03, 2018

IMAGES PROVIDED BY:

1) Evan Oto / Science Source

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SOURCES:

Academy of Nutrition and Dietetics: “Healthy Weight Gain.”

CDC: “Body Mass Index (BMI),” “Improving Your Eating Habits.”

Food and Nutrition Research: “Milk and dairy products: good or bad for human health? An assessment of the totality of scientific evidence.”

International Journal on Obesity: “Effects of food form on appetite and energy intake in lean and obese young adults.”

Familydoctor.org: “Healthy Ways to Gain Weight If You’re Underweight.”

Mayo Clinic: “What's a good way to gain weight if you're underweight?”

Reviewed by Melinda Ratini, DO, MS on January 03, 2018

This tool does not provide medical advice. See additional information.

THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for general informational purposes only and does not address individual circumstances. It is not a substitute for professional medical advice, diagnosis or treatment and should not be relied on to make decisions about your health. Never ignore professional medical advice in seeking treatment because of something you have read on the WebMD Site. If you think you may have a medical emergency, immediately call your doctor or dial 911.