High fat foods (think: greasy fried foods, burgers, rich buttery pastries, real cream in your coffee, or even one too many spoonfuls of peanut butter) – while tasty, can sometimes be a trigger of irritable bowel symptom (IBS) symptoms such as diarrhea, abdominal pain, loose stools, and upset stomach.
If you can relate, and find yourself running to the bathroom after a rich meal (or even a hearty cup of coffee with full-fat cream), you might potentially have a fat intolerance.
You may be tempted to go straight to a low-fat diet, for symptom management.
However, while a low-fat diet is a popular type of IBS diet prescribed by many gastrointestinal (GI) doctors nowadays, it isn’t the best long-term solution, IMO.
Read on to learn how to know if you have a fat intolerance, signs/symptoms, causes, and what you can do about it long-term from a holistic gut health nutrition perspective.
Disclaimer: This post was written for general educational purposes and may serve to complement/enhance, but NOT replace, medical or nutritional advice from your healthcare team.
Affiliate disclosure: This post contains affiliate links*. I may earn a commission on qualifying purchases made through some of the links in this post (marked with a * symbol), at no extra cost to you!
Table of Contents
Fat intolerance, in a nutshell (pun intended)
A fat intolerance is the inability to digest and absorb fats from foods efficiently in your digestive system.
(You may also hear practitioners refer to this condition as “maldigestion” or “fat malabsorption” in clinical settings.)
Signs and symptoms
When you eat foods that contain fat and your body isn’t able to break the fat molecules down into their elemental components, you may notice some or all of the following tell-tale signs/symptoms of fat malabsorption:
- Diarrhea / loose stools (Type 5, 6, or 7 on the Bristol Stool Chart) following fatty food consumption
- Light-colored stools
- Oily, greasy looking stools
- Floating stools
- Nausea, with or without vomiting (after high-fat meals)
- Sharp abdominal pain/cramping (upper or lower left or right side of abdomen) after a rich meal
- Fat-soluble vitamin deficiencies (vitamins A, D, E, and/or K) per micronutrient testing, even with supplementation
- High levels of steatocrit on a GI MAP test or other type of stool analysis test
- High blood levels of lipase (indicating pancreatic insufficiency)
Note that you may have be able to digest tolerate a certain THRESHOLD of fat in small quantities at one time; it’s not typically an “all-or-nothing” situation.
For example, you may be able to tolerate a few teaspoons of peanut butter but not a typical serving of 2 tablespoons.
Everyone’s oral tolerance to fat will be unique to them.
What causes it?
A fat intolerance won’t just show up out of the blue, for no reason. (PSA: Everything has a cause!)
There are dozens of possible explanations for why you might have developed a fat intolerance.
For example, there may be a defect in a digestive organ that is supposed to produce or release bile (liver/gallbladder), enzymes (pancreas/intestinal brush border), or another issue going on. (1)
Generally, the most common causes of a fat intolerance include (but aren’t limited to):
- Low stomach acid (hypochlorhydria)
- Acute infections
- Pancreatic disease/dysfunction
- Liver disease/dysfunction (i.e. cirrhosis)
- Alcoholism and/or polysubstance abuse (can lead to liver damage)
- Gallstones
- Gallbladder disease/dysfunction
- Gallbladder removal surgery
- Small intestinal bacterial overgrowth (SIBO)
- Celiac disease
- Crohn’s disease
- Colitis
- Diverticulitis
- Bowel cancer
- Radiation damage (from bowel cancer treatments)
- Cystic fibrosis
- Mold exposure & mold sickness (mycotoxins can become a HUGE burden the liver) (2)
- Bile acid diarrhea (3, 4, 5)
- Gut dysbiosis (6)
- Zollinger-Ellison syndrome (7)
- Whipple syndrome
- Certain genetic mutations impairing fat absorption
I also see fat malabsorption among some of my 1-1 clients with adult-onset sucrase-isomaltase deficiency, since it’s a condition which entails intestinal damage caused by SIBO, celiac disease, or inflammatory bowel disease (IBD).
Testing options
Note that it’s possible for you to experience more than one type of underlying condition.
Make sure you explore the etiology (aka underlying root cause) with your treatment team in terms of identifying the cause.
(Ideally I’d recommend a combination of diagnostic and functional testing, so you can address and manage it as holistically as possible!)
Clinical diagnostic testing
While diagnostic testing is outside my scope of practice as a registered dietitian, you can consult with your doctors about clinical testing, such as the following examples (this list is NOT exhaustive!):
- Serum lipase (indicative of pancreatic function)
- Clinical stool analysis
- Stool fat testing
- Liver function tests (LFT’s)
- Celiac blood test
- Intestinal biopsy
- SIBO breath testing
- Calprotectin test (may indicate IBD)
- Colonoscopy
- CT scan (type of X-ray imaging) of liver, gallbladder, stomach, pancreas, etc.
Functional testing
If you’re working with a functional dietitian nutritionist, you may also be able to run the following types of tests to look for patterns and degree of damage, in terms of fat intolerance/fat malabsorption:
- GI MAP, Gut Zoomer, or other type of functional stool analysis test (to assess microbial balance, gut pH, inflammatory markers, gut barrier integrity, gut-associated lymphoid tissue health, digestive sufficiency, presence of blood/mucous, stool color, stool consistency, etc.)
- Micronutrient testing (assess for fat-soluble vitamin deficiencies)
Long-term complications
If a fat intolerance is left unchecked for too long, even if you’re eating a balanced diet, you may potentially develop a fatty acid deficiency which can lead to symptoms and complications such as:
- Feeling hungry all the time
- Blood sugar roller coasters
- Fat-soluble vitamin deficiencies (A, D, E, K)
- Dry, flaking skin
- Unintentional weight loss
- Fatigue, weakness, and low energy
- Night blindness (from vitamin A deficiency)
- Osteopenia/osteoporosis (from deficiencies of vitamin D and/or vitamin K)
- Depression and apathy
- Infertility
- Compromised immune function
- Sluggish thyroid & slow metabolism
- Amenorrhea (if applicable)
- Infertility
Fat intolerance treatment options
Low fat diet
A low-fat diet is a popular go-to nutrition intervention in mainstream conventional medicine and dietetics.
And this may potentially serve you (alongside other dietary modifications/interventions, as needed) in the early stages of symptom management and relief..
However… IMO, I *generally* wouldn’t advise people to stay on a low-fat diet long-term! (Disclaimer: consult with your treatment team for dietary advice.)
Just because your digestive system isn’t correctly processing and tolerating fats from foods, doesn’t necessarily mean that your body doesn’t still need dietary fats!
- We need ~25 to 35% of our total daily calories to come from fat, for optimal health and wellbeing.
- Healthy fats are essential for brain & nervous system health, skin health, hormone balance, fertility, vitamin absorption, satiety, body temperature regulation, blood sugar regulation, and so much more.
Elemental diet
In severe cases of fat malabsorption, some people may benefit from consuming fats in elemental (pre-digested) form, typically alongside other interventions as needed.
These are available as pre-made nutrition shakes and supplements.
This should be done only under clinical guidance and supervision from your healthcare team.
Tube-feeding
When I worked in clinical hospital settings I would sometimes see GI patients receive pre-digested nutrition in liquid form, through a tube that would bypass the part of their gut that was not functioning properly, or post-intestinal resection.
For example, some patients might receive a jejunostomy tube or “J-tube” which delivers elemental nutrition directly into their intestines. However, this is rare and not typical as a stand-alone intervention for a simple fat intolerance but rather a post-op protocol.
Intravenous nutrition
In some cases, patients in clinical settings need to receive lipids and possibly other nutrients intravenously (directly into their blood) in order to bypass the part of their gut that is not currently working.
This is called total parenteral nutrition (TPN).
However, this intervention is generally only seen in extreme acute cases, short-term, and not
All of that said, whenever possible, I encourage my 1-1 clients to lean on supplemental digestive recommended long-term typically.
(We need to continue stimulating our gut (with food) in order to prevent it from atrophying. If we don’t use it, we lose it when it comes to our gut function!)
support to help liberalize their fat intake while optimizing their body’s ability to digest and absorb fats from their diet.
Supplemental digestive support
In my private functional nutrition practice, I work with my 1-1 clients on exploring supplemental digestive support options (as needed) to help aid in proper fat digestion so they can liberalize their fat intake to meet their daily minimum of ~25 to 35% of total calories from fat.
Below are some general examples of what that can look like.
Herbal bitters
Bitter-tasting herbs (such as gentian root), when taken in liquid form, have been shown to help stimulate digestive secretions such as bile and stomach acid, when they make direct contact with our bitter taste buds (located on the very back of our tongue). (8)
Learn more about how to get started with bitter herbs for digestive support here.
- Avoid this route if you have gallstones!
Digestive enzyme replacement therapy
Certain types of digestive enzyme supplements contain lipase (a pancreatic enzyme responsible for aiding in the breakdown fats) and/or certain food-derived constituents (such as beets) or other enzymes that can help reduce the burden on your gut.
TUDCA
TUDCA stands for “tauroursodeoxycholic acid.” (Don’t try to say that 10x fast!) 😉
It’s a special water-soluble bile acid conjugated with taurine, for optimal effectiveness at emulsifying fats.
This is a wonderful functional nutrition ally for anyone with digestive insufficiency, especially pertaining to the liver, gallbladder, or low stomach acid secretions. It’s been a game-changer for me and for many of my clients with gut issues!
It’s even safe during pregnancy (generally speaking).
Ox bile
This is a type of bile extracted from ox, and it’s a popular supplement (or ingredient) in nutraceuticals designed to help people post-gallbladder removal.
Recommended reading
- Expert Guidance on Peanut Butter and IBS
- Butter is Low FODMAP – But Is It IBS-Friendly? (What Else to Consider)
- Is Ghee Low FODMAP? What Else You Need to Know about Ghee and IBS
- Is Avocado Low FODMAP? (How to Navigate the FODMAPs in Avocados)
- High and Low FODMAP Cheeses – List & Guidance
- Low FODMAP Nuts, Seeds, Nut Butter and Peanuts – Oh My!
Final thoughts
Okay, this was a LOT of info about fat intolerance – probably more than you ever wanted to know, and a lot to digest – pun intended. 😀
Ultimately, fat intolerance often co-occurs alongside other types of adverse food reactions and should be identified and addressed sooner rather than later on your health journey.
Generally it’s not an “all or nothing” situation in that you may be able to tolerate smaller-than-normal quantities of fat at one time, but your digestive system is maxing out and hitting a capacity at lower levels of fat intake.
Fat intolerance also often co-occurs alongside other types of adverse food reactions and is a SYMPTOM of a deeper underlying condition.
Fortunately, there are lots of testing and treatment options available when it comes to identifying and treating the root cause of your fat intolerance (so you hopefully won’t get sentenced to a low-fat or fat-free diet for the rest of your life).
Supplemental digestive support such as herbal bitters, enzymes, TUDCA and/or ox bile can be game changers when it comes to improving your oral tolerance to normal and healthy amounts of fat in the diet.
As always, make sure you’re working with healthcare practitioners 1-1 to receive customized recommendations.
Next steps
If you’d like to continue learning more about the many ways you can navigate gut health more holistically, make sure to download my free gut health guide where I reveal 5 common IBS diet mistakes to avoid on your gut-healing journey!
For more customized guidance and support, if you live in the U.S, consider applying for 1-1 services here. (My team and I will review your application to make sure it’s a great mutual fit before we get back to you!)
XX – Jenna
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