9 Signs You Aren’t Digesting Fats and What To Do About It

signs you aren't digesting fatsIf you’re on a high-fat ketogenic diet and running on a fat-based metabolism, you need access to fat. Some of it comes from your own body, but not all. A good portion of your body’s fuel will come from dietary fat, or the fat you eat. Especially if you are eating more fat than you’re accustomed to, you need to be able to absorb and then digest the fat you eat and turn it into useable energy. If  you aren’t digesting fats, you may be in for some discomfort.

What are the signs and symptoms of poor fat digestion?

Signs You Aren’t Digesting Fats: What Does Fat Malabsorption Look Like?

Running a fat-based metabolism just doesn’t work if you can’t digest fats. Here’s what it looks and feels like:

Abdominal Pain and Discomfort After Fat-rich Meals

What happens to fat—or anything, really—that goes down the “wrong pipe”? When you consume fat but aren’t able to effectively digest it, that fat has to go somewhere. That fat goes where it isn’t supposed to be, and sometimes that causes pain and pressure.

Greasy Stool

Some misbegotten fat loss plans involve the active inhibition of fat digestion, either by consuming artificial fat-like substances that feel and taste like fat without providing any calories or taking lipase inhibitors which deactivate the intestinal enzymes that digest and absorb dietary fat. In both cases, the fat or “fat” is excreted when you go to the bathroom. Yeah. That’s not a good look, but it is a sure sign that you aren’t digesting fats.

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Floating Stool

Fat is buoyant. If your poop is festooned with the fat you ate but didn’t digest, it will float more readily.


Passive leakage into your underwear is another common sign you aren’t digesting your fat. One of the most infamous processed “food” disasters was a line of “WOW” branded snacks that contained an indigestible fat substitute, which caused people to leak stool without warning. Same mechanism.

Productive Flatulence

Apologies for the visual, but there’s no easy way to say it. People with poor fat digestion will often produce tangible, lasting results when they fart.

Unexpected Weight Loss

Not absorbing or digesting dietary fat will reduce your calorie absorption, and it may very well cause weight loss. But if you don’t have weight to lose, or if the weight loss comes with unwanted side effects (one study found that Orlistat users indeed lost weight, but they also lost more lean mass), you may want to pay attention.

Low Energy Levels

Trying to run on fat without actually being able to access dietary fat is a miserable exercise in futility. The boundless energy, the steady even keel, the ability to go for hours without eating or crashing—all the promises of fat-adaptation will elude you if you can’t digest the fat you eat.

Oxalate Accumulation

Orlistat users are at an increased risk of oxalate-induced kidney damage.1 Normally, oxalates bind to calcium to form calcium oxalate, which we excrete in the stool. With impaired fat digestion, the undigested fat binds with calcium, leaving oxalate adrift and more readily absorbed and accumulated. Less lipase, less fat digestion, more oxalate accumulation, more kidney danger.

Read Next: The Definitive Guide to the Carnivore Diet

Fat-soluble Vitamin Deficiencies

This isn’t an easy “sign” to watch for. You can’t really “feel” it. But if you were to go to a lab and get tested for vitamin D, vitamin E, vitamin K, and vitamin A, having low levels despite a steady intake could indicate a problem with your fat digestion. Orlistat research confirms this.2

But it’s a real issue. You absorb fat-soluble vitamins alongside the dietary fat you eat. If you’re not absorbing the fat, you’re missing out on the nutrients. All those studies which find that eating fat-soluble vitamins like vitamin E and vitamin K2 alongside dietary fat improves nutrient bioavailability assumes that you’re able to digest the fat. If you can’t digest the fat very well, you’re missing out on the rest of the stuff you eat.

Not all of these are individual markers of poor fat digestion. It’s normal to have some floaty stool now and again. You aren’t always going to digest every bit of fat you consume. Everyone can name a time they felt bloated and had a stomach ache after eating. There are many other reasons why you could be losing weight without trying. But if they are co-incident, you might be dealing with poor fat digestion.

And you should probably do something about it.

How to Improve Your Fat Digestion

Okay, so any, some, or all of those symptoms are signs of poor fat absorption and digestion. It’s always a good idea to rule out larger health problems with your doctor. Until then, what can you do about it?

Chew your Food Thoroughly

Most fat digestion occurs in the GI tract, but it starts in the mouth with something called lingual lipase, the oral form of the major fat-digesting enzyme. To produce lingual lipase, however, you have to chew. The simple presence of fat in the mouth isn’t enough—you have to get those teeth and that tongue going. In one study, eating almonds and coconut triggered the release of lingual lipase, while eating almond butter (the same amount of fat) did not.3 The only difference was chewing. Chew more to give your digestion a head start and improve your fat absorption, even if the food you’re eating doesn’t seem to require chewing. Do your best.

Check Your Gall Bladder

The primary role of the gall bladder is to collect bile from the liver, concentrate it into potent super-bile (my term), and release the concentrated bile to break up incoming dietary fat into smaller molecules that lipase (see above) can attack and digest.

If you gall bladder isn’t working properly, you still have bile—as that’s produced in the liver—but it’s not the concentrated stuff that’s really good at breaking up fat. You have “lesser” bile, bile that isn’t as strong or effective. Your dietary fat tolerance will drop unless you fix the gall bladder issue.

Address Your Gut Health

The gut is linked to just about everything in the body, and fat digestion is no exception. If you have an excessive amount of bacteria in your small intestine (remember, the bulk of your bacteria should reside in the colon), bile doesn’t work right. The bacteria start breaking it down, which inhibits the bile’s ability to break down the fats into the micelles that your lipase can digest.

I recently wrote a guide to fixing your gut health. Read that and employ some or all of the recommendations if they apply.

Take Extra Fat-soluble Vitamins

In studies where subjects have trouble digesting fats, they have to take extra fat-soluble vitamins, including vitamin E, vitamin A, and vitamin D, to avoid deficiency. This is a safe bet for the duration of your problem. I’d even throw in some vitamin K2 just to be safe—it’s really important but doesn’t get enough attention in typical studies.

Try Exogenous Digestive Enzymes and Bile Supplements

You can actually take exogenous lipase and bile supplements (like ox bile or bile salts). These aren’t as effective as the real thing (producing your own in-house), but they can give you a little help in that area.

If you have had your gall bladder removed, supplementing may be crucial to digesting fats. Run it by your doctor to see what he or she thinks.

Have Something Bitter After a Meal

Bitter flavors after a fat-rich meal enhance bile production.4 It doesn’t have to be some arcane bitter herb mix; even an espresso after a meal—that classic Italian custom—can improve fat digestion by increasing gastric acid production.5

Focus on Shorter Chained Fatty Acids

Shorter chained fatty acids like MCT oil and coconut oil are literally shorter and easier to disentangle for digestion. They don’t require as much bile to break apart as longer chained fatty acids. They are easily digested, head straight to the liver for oxidation or ketone generation without dealing with the lymphatic system, and can be utilized by cells for energy without the enzymatic processes needed to utilize longer chain fats.


I’m usually a proponent of listening to your body to tell you when you’re thirsty. “Drink when thirst ensures” works pretty well. But, since about 97% of bile is pure, unadulterated water, and one “silent” cause of fat malabsorption and trouble digesting fats is poor hydration status, this is something to consider. If you don’t have enough water, your bile production, texture, and function will suffer. It’ll be thick and sludgy, no good at all.

Drinking some water (perhaps with electrolytes) is an easy thing to try and it might actually be a missing piece.

Try Taurine

Taurine is a conditionally-essential amino acid. We make it, just not enough. One of the essential roles it plays is as substrate for bile production. Without adequate taurine levels, bile production—and, thus, fat digestion—suffers.6 Luckily, it’s an easy fix. Take a taurine supplement or eat more meat, especially hearts. Chicken, beef, lamb, turkey hearts are all great sources of taurine.

There you have it, folks. 9 signs and symptoms of poor fat digestion and 9 potential solutions to address the issue.

Do you have any problems digesting fat? Have you tried any of these recommendations? Do you have any recommendations of your own that weren’t listed here?


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Purchase Primal Kitchen Extra Virgin Olive Oil here.

About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

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