7 healthy ways to gain weight and build muscle fast, according to dietitians

© Oscar Wong/Getty Images 7 healthy ways to gain weight and build muscle fast, according to dietitians

• If you want to gain weight quickly, eat an additional 500 calories a day.
• To gain weight, eat high-calorie, yet nutritious foods like nuts, raisins, and peanut butter.
• If you are gaining weight, add strength training to ensure the added pounds are muscle and not fat.

Being overweight is a more common issue for Americans than being underweight, but that doesn't make being underweight any less unhealthy.

In fact, being underweight - a BMI of 18.5 or lower - can lead to health complications like a weakened immune system or fragile bones.

Many different factors can contribute to being underweight, like genetics, taking certain medications, not eating enough, or recovering from a serious illness.

If you need to gain weight or want to for aesthetic purposes, it's important to do so in a way that ensures you're getting proper nutrition. Here are seven tips for gaining weight in a healthy way.

1. Eat more calories

To gain weight, you'll need to eat more calories than you burn. On average, you'll need an additional 3,550 calories to safely gain one pound of body weight. If you're looking to put on a pound a week, that's about 500 additional calories a day.

Weight gain goals will differ by person and should be discussed with your doctor or a registered dietitian, but in general, a weight gain of about half to one pound a week is considered safe, says Jaime Gnau, RDN a biomedical sciences clinical instructor at Missouri State University's dietetics program.

Here is a breakdown:

Weight gain per week	Additional calories needed per day
0.5 lb	250
1 lb	500
2 lbs	1,000

Your metabolism also plays a role. If you have a fast metabolism, your body burns more calories at rest, which can make gaining weight difficult.

2. Choose high-calorie fruits and vegetables

Whether you're trying to gain, lose, or maintain your weight, eating a well-rounded diet of fruits, vegetables, protein, and grains is key to getting adequate amounts of vitamins and minerals.

An easy way to meet your daily fruit and vegetable requirements is to opt for high calorie produce like:

• Dates (66 calories per date)
• Raisins (120 calories in 1/4 cup)
• Black beans (220 calories in 1/2 cup)
• Bananas (112 calories per fruit)

3. Eat energy-dense foods

One way to consume more calories without feeling overly full is to eat energy-dense foods, Gnau says, which have more calories per gram.

Energy-dense foods include:

• Avocados (240 calories per fruit)
• Nuts, like almonds (180 calories in a ¼ cup)
• Olive oil (120 calories in one tablespoon)
• Dried fruit, like apricots (90 calories for about five pieces)

Important: Even if you're trying to gain weight, it's important to consume mostly nutritious foods. Baked goods, like pie, cake, and cookies are also high in calories and fine to consume in moderation, Gnau says. But these foods contain added sugars, which can increase your risk of heart disease, so it's best to limit your intake.

4. Drink your calories

Beverages like smoothies or protein-packed shakes can also help add calories to your daily intake. Some examples of high-calorie beverages include:

• Smoothies with peanut butter, chia seeds, fruit, yogurt, and whole milk.
• 100% fruit juice which has more calories than whole fruit. Healthy people can include a serving of 100% juice each day as one of their fruit servings.
• Unsweetened protein powder, which can be added to drinks, oatmeal, or yogurt.

5. Add extras like condiments, sauces, and toppings

Adding sauces and toppings to foods can help bump up your calorie intake, Gnau says. Some condiments and toppings to add to meals include:

• Topping chili with shredded cheese (about 110 calories per ¼ cup).
• Spreading peanut butter (about 190 calories for two tablespoons) or almond butter (about 190 calories for two tablespoons) on toast or pancakes.
• Preparing roasted vegetables with olive oil (120 calories per tablespoon).
• Topping salads with sunflower seeds (85 calories per tablespoon) and shredded cheese (about 110 calories per ¼ cup).

General advice: Adding extras can help boost calorie intake, but be aware of added sugars, sodium, and saturated fat, in sauces and condiments.

6. Increase protein intake

Muscles are made of protein, so eating more protein while strength training ensures those extra calories go toward building muscle and not fat.

What the research says: A small 2012 study examined the effects of low, moderate, and high protein diets on weight gain. Participants ate a caloric surplus for eight weeks, with one group receiving a 5% protein diet, another a 15% protein diet, and another a 25% protein diet. Individuals in the highest protein diet group gained about 14 pounds, while those in the lowest group gained about seven pounds. Body fat composition was the same across all groups.

In general 0.5 to 0.8 grams of protein per pound of body weight has been shown to help with weight gain.

Examples of high-protein foods include:

• Salmon (29 grams of protein in five ounces)
• Eggs (6 grams of protein per egg)
• Beans (6 grams of protein per ½ cup of black beans)
• Nuts (6 grams of protein her ¼ cup)

Excess protein can increase the chance of dehydration so be sure you're drinking plenty of water when increasing protein intake. Gnau recommends limiting your protein intake to no more than 35% of your daily calories. It's also a good idea to talk with your doctor or a registered dietitian to develop an individualized plan.

7. Start lifting weights

Strength training can help you gain weight by building muscle, says Jenna Coker-Jones a health and fitness coach with her own private practice.

General advice: Jones recommends weight training at least three to four days a week and lifting heavy enough weights that you can only do six to eight reps at a time.

Try to avoid intense cardio, like running, because it could burn the additional calories you're eating and prohibit weight gain. Instead, opt for low-impact cardio like walking.

"Walking is such an important resource that many don't use it for training," Jones says. "You get the benefits of being outside and it's a great addition to strength work if you want to do less cardio and more gaining."

Insider's takeaway

If you need to put on weight safely and healthily, focus on eating more nutritious energy-dense foods, increasing your protein intake, and lifting weights. Everyone's goals will be different, but in general, a healthy range for weight gain is about 0.5 to 1 pound per week, Gnau says.

Always check in with your doctor before changing your diet and workout routine. A registered dietitian can also help develop a plan to help you meet your goals.

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