The 4 Best Protein Bars for Weight Gain, According to a Dietitian

Whether you're trying to gain weight in the form of muscle mass or looking to add a few pounds for health reasons, taking in adequate calories can sometimes be tricky. Enter protein weight-gain bars, a convenient snack that can supplement your diet with extra calories.

First, the basics: If weight gain is your goal, you'll need to eat more calories than you burn, according to the Cleveland Clinic. As a result, you want to pick a protein bar that's high in calories.

But make sure that the protein bar you pick is full of nutritious calories from natural sources of protein (like nuts and seeds), rather than non-beneficial calories from artificial sweeteners, says Isabel Smith, RD, CDN, a New York City-based registered dietitian.

To help you get started, here are four of the best protein bars for weight gain, according to a dietitian.

Here are Smith's recommendations for protein bars to gain weight:

Clif Builders are packed with nutrient-dense calories (290 calories per bar) and a whopping 20 grams of plant protein, Smith says. Even better, these bars don't contain any artificial sweeteners and instead get their delicious flavor from ingredients like peanut and cocoa butter.

Try flavors like peanut butter, chocolate mint and vanilla almond to pick the best bar for your taste.

Load up on a Perfect Bar, which packs 350 calories and as many as 16 grams of protein per serving. Smith says these bars also contain minimal added ingredients — and no artificial sweeteners — which makes them a nutritious alternative to more highly processed products.

Shop flavors like dark chocolate chip peanut butter, snickerdoodle and salted caramel for a high-calorie, protein-rich treat for your weight-gain diet.

Get your fill of vitamins, minerals and protein (15 grams, to be exact) by tucking into a Sans Bar. These bars clock in at 390 calories per serving and contain no added sugars or artificial sweeteners — instead, they get their flavor from natural ingredients like dates, coconut, spices and nuts.

As an added bonus, these bars are dairy-, gluten- and soy-free, making them the perfect option if you have certain dietary restrictions.

Get plant-based protein aplenty (up to 12 grams per serving) by munching on a ProBar, a gluten- and soy-free protein snack that also packs in nutritious fiber from ingredients like chia and flax seeds.

The bars come in fruity, nutty and dessert-like flavors like wholeberry blast, peanut butter and chocolate coconut, and contain up to 390 calories per bar.

The ingredients and nutritional value of weight-gain protein bars depends on which product you buy. But in general, here's what to look for on the label:

• ​Calories:​ Smith recommends picking a bar that contains at least 300 calories. She says there are some options that contain as many as 700 calories, but these dense snacks may cause stomach upset.
• ​Protein:​ A bar should have at least 8 grams of protein, per the Columbia University Irving Medical Center (CUIMC).
• ​Fat:​ A bar should also contain at least 5 grams of fat, per the CUIMC, ideally a beneficial source of the nutrient like nuts, nut butters or flaxseed oil.
• ​Complex carbohydrates:​ Complex carbs provide sustained energy, so look for sources of the macro from whole grains like brown rice, oats or quinoa, per the Cleveland Clinic.

On the flip side, beware of bars that say they're sugar-free but contain sugar alcohols. These ingredients may cause digestive symptoms like bloating, gas and diarrhea, according to the Mayo Clinic.

The same goes for weight-gainer protein bars that contain refined sugars — these are not only void of nutrition, but they can also lead to blood sugar spikes and subsequent crashes, per the Harvard T.H. Chan School of Public Health.

According to the Mayo Clinic, types of added sugars to steer clear of include:

• Fructose
• Glucose
• Maltose
• Dextrose
• High-fructose corn syrup
• Cane juice or syrup
• Malt

You'll also want to read the label to check that your weight-gain bars are free of trans fats, which can contribute to high cholesterol levels, per the U.S. National Library of Medicine.

Natural foods are the best source of nutrition for your body, Smith says. That's why it's best to get most of your protein from lean meats, legumes and vegetables.

While protein bars are convenient, they may contain added sugars that natural protein sources don't. Additionally, choosing bars over whole foods may cause you to miss out on the essential nutrients and fiber you'd normally get in food.

Accordingly, it may be best to save your weight-gain bars for when you're short on time or out and about, per the CUIMC. Otherwise, opt for protein-dense foods.

Pre-made protein bars may be convenient and fit your calorie needs, but to ensure you're getting one that's exactly right for you, a better option could be to make your own.

Use ingredients like protein powder, whole grains, nuts, seeds, dried fruit and nut butter to make a high-calorie bar at home.