It’s common to hear about the health risks of having obesity and overweight, but being underweight can cause health problems, too. Underweight means you have a body mass index (BMI) below 18.5, and it can lead to infertility, a weakened immune system and sleep issues.

It can also be a vicious cycle: Certain medical conditions like cancer, Type 1 diabetes and hyperthyroidism can cause you to burn more calories than you consume, which leads to weight loss. But then, being underweight is a risk factor for additional health concerns.

Some lifestyle habits and circumstances can lead you to need high-calorie snack ideas as well, like if you lost weight during a long hospital stay, or if you burn a lot of active calories at your job or through frequent workouts. And sometimes, it’s just genetics: Some people were born with a high metabolism rate.

“Whatever the case, if your healthcare provider is concerned that you’re underweight, they may recommend a high-calorie, high-protein diet to help you add extra pounds,” says registered dietitian Julia Zumpano, RD, LD.

Healthy, high-calorie foods

Let’s start off by talking about what not to do when you’re trying to gain weight. Namely, don’t turn to a bunch of junk food. Eating chips, sugary sodas, donuts and candy will add pounds, but it won’t be the source of a healthy weight gain.

“This weight will mostly end up around your belly, which puts you at a higher risk for diabetes and heart disease,” Zumpano warns. “Instead, eat protein-rich foods that build muscle.”

The main concept of gaining weight is that you have to eat more calories than the amount your body burns.

“It’s better for your body to gain weight slowly than to put on weight quickly,” Zumpano notes, “so to gain weight slowly, eat an extra 300 to 500 calories per day.” She also recommends eating small meals every three to five hours and snacks throughout the day to help you consume more without feeling overly full.

But what exactly should you be snacking on? Let’s take a look at some of the foods that can help you gain weight.

Nuts

Nuts are high in protein and healthy vitamins and minerals, among other health benefits. Two major health studies found that people who ate 5 ounces or more of nuts each week lowered their risk of heart disease by as much as 50%.

The monounsaturated fat in nuts is the “good” kind that can help you manage your cholesterol, and a 1-ounce serving alone has about 160 to 200 calories. This makes nuts — including almonds, pistachios and walnuts — a good (and tasty) choice when you’re trying to gain weight, whether you snack on nuts alone, add them to a salad or combine them with dried fruit into a trail mix.

“To make sure you’re not increasing your intake of extra sugar and sodium, stick to plain, unsalted nuts, or make your own spice blend for them,” Zumpano suggests.

Recipes to try:

Nut butters

Don’t forget about nut butters! They have many of the same health benefits as nuts themselves, but they’re a super-versatile ingredient in a variety of dishes and snacks.

“Just be on the lookout for added sugars and oils,” Zumpano warns. “All you need in a nut or seed butter is the nuts or seeds themselves.”

One of the quickest, easiest snacks in the book is to add spread 2 tablespoons of natural peanut butter (or other nut butter) atop a sliced apple or banana. Yum! And an English muffin with a tablespoon of your choice of natural nut butter will typically add around 250 calories to your diet.

Recipes to try:

Greek yogurt

Greek yogurt is strained to create a rich, creamy texture. It has about twice as much protein as traditional yogurt, and far more calories. It’s also a great source of calcium (for strong bones) and probiotics (for a healthy gut).

“Greek yogurt makes for a great base, especially when you’re trying to gain weight,” Zumpano says. “Be sure to use whole-milk Greek yogurt for extra calories and fat.”

Recipes to try:

• Start your day or grab a snack with a sweet banana smoothie.
• Half a cup of Greek yogurt with 1 tablespoon of honey and 1 tablespoon of chopped nuts, seeds, dried fruit, or chia or flax seeds will run you about 300 calories.
• Looking for a delicious dip? Greek yogurt is the perfect base for creamy faves like spinach and artichoke dip.

Eggs

One egg gives you 78 calories and 6 grams of protein. They’re also relatively inexpensive and accessible. “Eggs can be a great source of high-quality protein and a variety of nutrients,” Zumpano says.

Egg whites are safe to eat as often as you’d like, but when eaten in excess, eggs yolks can raise your LDL (“bad”) cholesterol levels. If you have cardiovascular disease or high cholesterol, it’s best to limit your egg yolk consumption to just four per week. Check with a healthcare provider to see what’s best for you.

Recipes to try:

• Creamy curried egg salad lends classic Indian flavors to a favorite American snack — and this recipe also teaches you a handy trick for making hard-boiled eggs that are easy to peel!
• When you’ve got a little bit of time to cook up a snack, scrambled eggs are a great go-to, especially when you add in chopped tomatoes, fresh herbs and creamy goat cheese.
• Deviled eggs aren’t just a party food. Make and snack on your own with this version that includes minced dill pickles. 

Protein powder

“Protein powder doesn’t offer the same kind of nutritional value that whole foods do, but it can help boost your protein intake and add extra calories,” Zumpano states.

Whey, hemp, rice or pea are all good protein powder options. Just be sure to look for a version that isn’t loaded with artificial sweeteners and other additives.

Recipes to try:

Cottage cheese

Cottage cheese has a mild flavor and serious health benefits. It’s high in protein and calcium, which is great for your bones, and it’s an extremely versatile food: Use it as a dip, put some on top of toast or bake it into pancakes and muffins to make them extra fluffy.

Cottage cheese comes in nonfat, low fat (1% or 2%) or whole fat varieties, and full-fat cottage has 1.5 grams more of saturated fat than 2% cottage cheese does.

“For people trying to lose weight, a lower-fat cottage cheese is a great choice, but when you’re trying to gain weight, aim for whole-fat cottage cheese,” Zumpano advises.

Recipes to try:

• Did you know that you can even put cottage cheese in smoothies?! This berry banana smoothie also includes milk, fruit and a little vanilla extract for extra flavor.
• Most muffins are low in nutrients, but these cranberry orange muffins are high in protein while still super-moist. When you’re trying to gain weight, swap out low-fat cottage cheese for the regular version.
• Make your own miniature spinach-filled spanakopita with a cottage cheese/feta blend and frozen phyllo dough.

Avocado

Guac is definitely extra — extra healthy fats, that is! About three-quarters of the calories in avocados are from monounsaturated fats, and they’re full of vitamins and nutrients. 

This fruit (did you know that avocadoes aren’t vegetables?!) is so versatile that it can easily be incorporated in everything from snacks and salads to smoothies and sweets.

“You can use avocado to replace other fats, you can enjoy the flavor and nutrients and also cut down on saturated fats,” Zumpano says.

Recipes to try:

• Keep it classic: Half an avocado on a slice toast will add about 250 calories, or you can elevate it a bit with this version with radish, cucumber and dill.
• Skip store-bought guacamole and make your own instead, using it as a dip for tortilla chips or veggies.
• Avocados for dessert?! Try avocado brownie bites for a rich, decadent and surprisingly healthy snack. They’re about 165 calories apiece.

‘Extras’

Looking for an easy way to add calories to your meals? “Add condiments that are high in healthy fats,” Zumpano suggests. Examples include:

You can also add natural sweeteners like dried fruit, honey or maple syrup. Just be careful not to veer into ultra-processed territory, adding condiments that are loaded with additives like colorings and preservatives.

“They add calories, yes, but they can also cause inflammation in the body,” Zumpano cautions. “If weight gain is your goal, give each meal and snack a boost by adding an ‘extra’ to the meal.” You can:

• Drizzle EVOO over steamed veggies or add it to soup or hummus.
• Throw chopped nuts or seeds into your oatmeal, salad, rice dish or veggies.
• Dip veggies, whole-grain crackers or pita wedges with hummus and/or cheese.
• Slice avocado over eggs, toast, crackers, salad or soups.

Other tips for gaining weight the healthy way

Zumpano shares some additional snack and diet tips for when you’re trying you put on weight the healthy way:

• Go for full-fat dairy products: Instead of using nonfat or low-fat milk, use whole milk or cream in scrambled eggs, soups, gravies and baked goods. If you’re lactose intolerant, turn to alternative milks.
• Choose higher fat meats: Steak, pot roast, ribs, pork chops and chicken or turkey thighs and legs have a higher fat content than leaner cuts of meat.
• Don’t fill up on fluids: Avoid drinking water or other beverages 30 minutes before you eat, as they can fill you up and cause you to eat less. “You can add calories through drinks, though, like by adding whole milk to your coffee and drinking 100% fruit juices, shakes or smoothies,” Zumpano says.

Healthcare providers typically advise scaling back on foods that are high in fats, so if you’ve ever tried to lose weight in the past, some of these tips will feel counterintuitive. But remember that you won’t be following them forever — just while you’re trying to get to a healthy weight.

“From there, your doctor or dietitian can help you modify your diet again to something that’s healthy and sustainable for the long-term,” Zumpano says.