3 Reasons Protein Bars Give You Gas (and 5 Options That Won't)

Protein bars offer a convenient way to get more of the important nutrient. But for some people, they come with uncomfortable tummy issues, like gas and bloating.

In fact, there are many reasons protein bars may give you gas. It could be the protein itself or another added ingredient that's not sitting right with you. Many also contain a lot of fiber, which can take time for your body to adjust to.

If you're eating protein bars and stomach pain follows, it may be time to do some troubleshooting to figure out what the underlying problem is. Otherwise, it may be wise to switch to a different protein bar that doesn't cause gas. We've listed some of our favorites below.

Before we dive into other protein bar options, why do protein bars give you gas? We tapped three registered dietitians to get to the bottom of it.

Gas and flatulence are common complaints when first starting out on a high-protein diet. If you're eating protein bars as part of a high-protein diet, it's possible that you're just getting too much protein in a short period of time and your digestive system is having trouble with it.

Proteins take longer to break down in the stomach than carbs, and milk-based proteins like whey and casein, which are commonly found in protein bars, is one of the slowest digesting proteins of all, according to the International Milk Genomics Consortium.

This is one of the major reasons protein is tied to weight loss: It helps keep you full longer so that you're less likely to overeat.

But taking in a lot of protein in a short period of time — like if you have whey protein powder — can cause gas, bloating and discomfort.

Another reason why your protein bar may be causing gas is that you have an allergy or sensitivity to one of the ingredients in it.

For example, whey protein: "Because it comes from milk, it contains lactose, which is a sugar many people have trouble breaking down," says Katie Tomaschko, RDN, a registered dietitian based in Buffalo, New York. "If you have trouble digesting lactose, products with whey can cause gas."

If you're often gassy after eating a protein bar that's labeled "keto-friendly," "low-carb" or "low-sugar," the likely culprit is artificial sweeteners.

Sugar alcohols, including mannitol, erythritol and xylitol, are known for causing digestive upset, gas and bloating, says Amy Shapiro, RD, registered dietitian and founder of Real Nutrition.

"Much like fiber, sugar alcohols go through our system and the bacteria in our colon to try to break them down," she says. "In the process they release carbon dioxide, which can cause gas, bloating and even diarrhea in people with sensitive stomachs."

Selecting the right protein bar for you will depend on your body and digestive system. You may have to try different options before you find the right one, but the list below, which features quality products from trusted brands, is a good place to start.

These products are all made and sweetened with whole-food ingredients, and many contain protein sources that are easier on your stomach.

• ‌Protein: 10 grams‌

These cookie-dough-flavored protein bars are made with whole-food ingredients and without soy, gluten or artificial additives.

"What makes this bar ideal for digestion is that it's crafted from whole-food ingredients and naturally sweetened," Shapiro says. Plus, each one gives you 10 grams of satiating protein.

• ‌Protein: 11 grams‌

Made with cashew butter, coconut oil and vanilla extract, Bulletproof's Collagen Protein Bar has the texture of a cookie without exorbitant amounts of sugar. "This bar has protein from hydrolyzed collagen, which is a clean form of protein most people can digest," Shapiro says.

Each pack comes with 12 bars, with each bar delivering 11 grams of protein and just 2 grams of sugar. Choose from four cookie- and dessert-inspired flavors.

• ‌Protein: 20 grams‌

A busy day calls for a satiating snack, and these bars are made with whole ingredients, such as organic almonds and honey for a hint of sweetness. Even more, they're an excellent source of fiber and healthy fats. These protein bars also come in a variety of flavors, including unique options like Mint Chocolate Chip and Snickerdoodle.

• ‌Protein: 12 grams‌

This crunchy protein bar comes recommended by Dana Ellis Hunnes, PhD, RD, a senior clinical dietitian at UCLA Medical Center and assistant professor at UCLA's Fielding School of Public Health. "These have easily recognizable whole ingredients and are among the healthiest bars I've seen," she says.

• ‌Protein: 10 grams‌

This plant-based protein bar only contains five ingredients: dates, peanuts, gluten-free oats, almond protein and salt.

These ingredients are easily digestible, Dr. Hunnes says. Each bite is soft and chewy thanks to the mixture of dates and oats.