Do you fart more when you have more protein?

October 18, 2025 •

3 min read

The average person passes gas between 12 and 25 times per day. For those who increase their protein intake, particularly with supplements, a noticeable rise in flatulence often occurs, leading many to ask, "Do you fart more when you have more protein?"

Quick Summary

Limited scientific evidence links protein directly to increased gas volume, though it can cause a stronger odor. Factors like protein powder additives, lactose, fiber intake, and digestion speed are the real culprits behind the change. Simple dietary adjustments and mindful eating can manage symptoms effectively.

Key Points

Protein isn't the main cause: The volume of gas isn't directly increased by protein itself, but rather by other components often consumed alongside it, such as added fibers or supplements.
Sulfur causes the smell: The foul odor often associated with 'protein farts' comes from sulfur-containing amino acids in certain protein-rich foods like meat and eggs.
Supplements contain hidden culprits: Many protein powders and bars contain additives like lactose, sugar alcohols (sorbitol, xylitol), and thickeners that ferment in the gut and produce gas.
Fiber matters: A high-protein diet, especially one rich in plant-based sources, can increase fiber intake, which can lead to gas if the gut isn't accustomed to it.
Digestion speed plays a role: Eating too quickly can cause you to swallow more air, while high-fat protein sources can slow digestion, giving bacteria more time to produce gas.
Consider alternative protein sources: Switching from whey concentrate to whey isolate or a plant-based protein can help if lactose is the issue.

The Surprising Truth: It's Not the Protein Itself

Despite popular belief, scientific evidence suggests that protein itself is not the primary cause of increased flatulence. The myth that you fart more when you have more protein stems from the common dietary changes people make when they increase their protein consumption. The real culprits are often additives in supplements, changes in fiber intake, or difficulties digesting certain components found in high-protein foods.

The Real Culprits Behind the Gas

Additives in Protein Powders: Many protein supplements contain added sweeteners, thickeners, and fillers that are difficult for the body to digest. Sugar alcohols like sorbitol, xylitol, and mannitol are particularly known for causing gas, bloating, and other GI issues.
Lactose in Dairy-Based Protein: Whey and casein protein powders are derived from milk and contain lactose. If you have lactose intolerance—a condition affecting millions—your body lacks the enzyme lactase to properly break down this sugar. Undigested lactose ferments in the large intestine, leading to significant gas production.
High-Fiber Accompaniments: Often, a high-protein diet is paired with an increased intake of fibrous plant-based foods, such as beans, legumes, and certain vegetables. While fiber is crucial for digestive health, a sudden and large increase can overload the gut, causing bacteria to produce more gas during fermentation.
Slowed Digestion from Fatty Proteins: Eating high-fat cuts of meat can slow down the digestive process. The longer food sits in your digestive tract, the more time bacteria have to ferment it, which can contribute to gas.

Why Protein Causes Smellier Farts

While protein doesn't necessarily increase the volume of gas, it can significantly affect its odor. This is due to the presence of sulfur-containing amino acids in certain protein sources.

When sulfur-rich foods are broken down by gut bacteria, a byproduct called hydrogen sulfide is released. This compound is responsible for the classic, foul, rotten-egg smell. High-sulfur protein sources include:

Red meat
Eggs
Dairy products
Whey protein with high cysteine content

Comparison Table: Causes of Protein-Related Gas


Culprit	Mechanism	Effect on Gas Volume	Effect on Gas Odor
Protein Supplements	Additives like sugar alcohols ferment in the gut.	Increases	Can increase
Lactose Intolerance	Undigested lactose ferments in the large intestine.	Increases	Minor effect
Increased Fiber	Sudden increase in fiber leads to bacterial fermentation.	Increases	Can increase
Sulfur-Rich Proteins	Sulfur-containing amino acids produce hydrogen sulfide.	No direct increase	Increases significantly
Eating Too Fast	Swallowing excess air while gulping food or shakes.	Increases	No effect

How to Minimize Protein-Induced Gas

Here are some strategies to manage the gassy side effects of a high-protein diet:

Evaluate your protein source: If you use protein powder, consider switching to a lower-lactose option like whey protein isolate or a plant-based alternative such as pea or hemp protein. Always check the ingredient list for sugar alcohols and other additives.
Increase fiber gradually: If your diet is low in fiber, introduce high-fiber foods slowly to allow your digestive system to adapt. This gives your gut bacteria time to adjust without overwhelming them with a new food source.
Stay hydrated: Drinking plenty of water helps move waste through your digestive system, preventing constipation and fermentation.
Slow down your meals: When you eat too quickly, you swallow more air, which contributes to gas. Chewing your food thoroughly and taking your time with protein shakes can make a difference.
Use digestive aids: Peppermint or ginger tea can help soothe the digestive tract and relieve gas. Digestive enzymes may also aid in the breakdown of difficult-to-digest carbs in plant-based proteins.

Conclusion: Focus on What Comes With the Protein

While the association between increased protein and gas is a common one, the science indicates that protein is rarely the direct cause of increased flatulence. Instead, the effects are usually a result of other factors often associated with a high-protein diet, such as lactose from dairy-based supplements, fermentable fibers, or digestion-slowing additives. By identifying and adjusting these elements, you can continue to enjoy the benefits of a protein-rich diet without the uncomfortable gassy side effects. Addressing these underlying issues, rather than blaming the protein itself, is the key to a happier, healthier gut. Find a primary care physician in your area today to discuss persistent or severe digestive symptoms.

Frequently Asked Questions

The unpleasant odor is primarily caused by sulfur-containing amino acids found in protein sources like red meat and eggs. When gut bacteria break down these compounds, they produce foul-smelling hydrogen sulfide gas.

Yes, but it's usually not the protein itself. Many protein powders contain additives like sugar alcohols (e.g., sorbitol, xylitol) and fillers, or are dairy-based (whey, casein) which can cause gas in individuals with lactose intolerance.

Whey protein concentrate contains more lactose, which can cause gas and bloating for lactose-intolerant individuals. Whey protein isolate is more filtered and contains significantly less lactose, making it easier to digest for many.

Yes, incorporating sufficient fiber can help. It promotes smoother, more regular digestion, preventing undigested food from fermenting excessively in the gut. However, increase fiber intake gradually to avoid an initial spike in gas.

Plant-based proteins, particularly legumes and beans, contain indigestible carbohydrates (oligosaccharides) and high amounts of fiber. These are fermented by gut bacteria, which can lead to increased gas, especially when you first start consuming them.

Yes, it's common for your digestive system to go through an adjustment period when you significantly increase your protein and fiber intake. Symptoms like increased gas and bloating should typically subside within a few weeks as your body adapts.

To reduce gas from protein shakes, consider using a lower-lactose or plant-based protein powder, drink it slowly to avoid swallowing excess air, and check for gas-causing additives like sugar alcohols.