People are often told that eating fat causes gallstones or that a low-carbohydrate diet is unsafe for the gallbladder. The physiology tells a more interesting story.
Dietary fat stimulates the gallbladder to contract and release bile. During rapid weight loss, diets that are extremely low in both calories and fat can reduce gallbladder emptying and promote bile stasis. Randomized-trial evidence has found that including more dietary fat during weight loss can reduce gallstone formation compared with very-low-fat regimens.[1,2]
At the same time, eating fat can trigger pain when gallstones already exist. The fat does not suddenly create a stone. It stimulates the gallbladder to squeeze, and a stone obstructing the outlet or bile duct can make that contraction painful.
This distinction matters. Dietary fat helps an unobstructed gallbladder empty, but it can expose an existing obstruction.
What the gallbladder does
The liver continuously produces bile, which helps the body digest and absorb dietary fat and fat-soluble vitamins. The gallbladder stores and concentrates that bile between meals.
When fat and protein reach the small intestine, the digestive system releases cholecystokinin, or CCK. CCK signals the gallbladder to contract and send bile through the bile ducts into the intestine.
When meals contain almost no fat or protein, the gallbladder receives less stimulation and empties less completely. During severe calorie restriction and rapid weight loss, this can combine with changes in bile composition that favor cholesterol-crystal and gallstone formation.[1–3,5,6]
What gallstones are
Gallstones are hardened deposits that form in the gallbladder. Most are made primarily of cholesterol; others are made from bilirubin and are called pigment stones.[5]
Many gallstones cause no symptoms and are discovered incidentally. Problems begin when a stone obstructs the cystic duct or common bile duct.
Data point: Gallstones affect an estimated 10% to 15% of the U.S. population—nearly 25 million people. European clinical guidance estimates that about 80% of people who carry gallstones have no symptoms.[5,6]
Gallstones can lead to:
- Biliary colic: episodic upper-right or upper-middle abdominal pain, often after a meal
- Acute cholecystitis: inflammation of the gallbladder
- Choledocholithiasis: a stone in the common bile duct
- Cholangitis: infection within an obstructed bile-duct system
- Gallstone pancreatitis: inflammation of the pancreas caused by a migrating stone
What increases gallstone risk?
Gallstones do not have one single dietary cause. Risk develops from the interaction of bile chemistry, gallbladder emptying, body weight, metabolic health, hormones, genetics and the rate of weight change.
Important risk factors include:
- Obesity and abdominal adiposity
- Insulin resistance, type 2 diabetes and high triglycerides
- Rapid weight loss
- Very-low-calorie dieting
- Bariatric surgery
- Pregnancy and estrogen exposure
- Increasing age
- Family history and certain genetic backgrounds
- Liver, blood or intestinal diseases that alter bilirubin or bile-acid metabolism
- Diets high in calories and refined carbohydrates and low in fiber[5,6]
Obesity raises gallstone risk, but losing weight very quickly can raise it too. This is why the method and pace of weight loss matter.
Why very-low-fat dieting can be counterproductive
The original Toward Health article centered on three studies showing how very-low-fat, low-calorie diets affect the gallbladder.
Higher fat intake maintained gallbladder emptying during rapid weight loss
In a six-month study of adults with obesity following very-low-calorie diets, one group consumed approximately 3 grams of fat per day and another consumed approximately 12 grams per day during the most calorie-restricted phase. The higher-fat meals produced greater gallbladder emptying. Among participants who completed the study, gallstones developed in 6 of 11 people—54.5%—in the lower-fat group and in none of the 11 people in the higher-fat group.[1]
A meta-analysis found fewer gallstones with higher-fat weight-loss diets
A meta-analysis of 13 randomized trials involving 1,836 participants examined gallstone prevention during diet-induced weight loss or after bariatric surgery. Diets higher in fat reduced gallstone risk compared with lower-fat diets (risk ratio 0.09; 95% CI, 0.01–0.61). Ursodeoxycholic acid, or ursodiol, reduced ultrasound-confirmed gallstones (risk ratio 0.33; 95% CI, 0.18–0.60), with a number needed to treat of 9, and reduced surgery for symptomatic stones (risk ratio 0.20; 95% CI, 0.07–0.53).[2]
Low-calorie meals produced less gallbladder emptying
An earlier physiologic study compared gallbladder emptying after a regular meal and a low-calorie meal in 21 people with obesity and 30 people without obesity. The low-calorie meal produced less gallbladder emptying. In the seven participants with obesity reassessed after 10 days on the low-calorie regimen, fasting gallbladder volume increased, supporting the connection between reduced meal stimulation, bile stasis and stone formation.[3]
The practical conclusion is straightforward: during weight loss, eliminating nearly all dietary fat is not protective for the gallbladder. Adequate dietary fat helps maintain normal gallbladder contraction.
What about carbohydrates?
The original Toward Health article also cited a large prospective study of men that examined carbohydrate intake and symptomatic gallstone disease. Researchers followed 44,525 men for 12 years and documented 1,810 new symptomatic gallstone cases. Compared with the lowest intake group, the highest carbohydrate-intake group had a 59% higher risk, the highest glycemic-load group had a 50% higher risk and the highest glycemic-index group had an 18% higher risk after multivariable adjustment.[4]
Refined-carbohydrate intake also travels with metabolic conditions that contribute to gallstones, including insulin resistance, high triglycerides, abdominal obesity and fatty liver.
A well-formulated low-carbohydrate diet addresses these factors by reducing sugar and refined starch while supplying adequate protein and enough dietary fat to support satiety and gallbladder emptying. A low-carb diet does not require force-feeding fat or eating unusually greasy meals.
Can a low-carb or ketogenic diet cause gallstones?
Carbohydrate restriction itself is not established as a cause of gallstones. The more relevant concerns are:
- Starting with gallstones that were already present
- Losing weight very rapidly
- Eating too little total energy for a prolonged period
- Combining rapid weight loss with extremely low fat intake
- Developing symptoms when a meal stimulates a gallbladder that contains an obstructing stone
People who begin a low-carbohydrate or ketogenic diet and then experience upper-right abdominal pain may assume that dietary fat created a new gallstone. More often, the meal has triggered contraction of a gallbladder containing pre-existing stones or sludge.
This symptom should be evaluated rather than managed by repeatedly removing more foods without a diagnosis.
If you already have gallstones
There is an important difference between preventing stones and managing symptoms after stones have formed.
When stones are present, a fatty meal can provoke a forceful gallbladder contraction and trigger biliary colic. Temporarily reducing the amount of fat eaten at one time may lessen attacks while the person is being evaluated. That does not mean a very-low-fat diet will dissolve the stones or correct an obstruction.
Asymptomatic gallstones often require no treatment. EASL guidance estimates that symptoms develop in about 1% to 4% of people with asymptomatic stones each year, with approximately 20% becoming symptomatic within 20 years. Recurrent pain, gallbladder inflammation, bile-duct stones or gallstone pancreatitis commonly leads to laparoscopic cholecystectomy, the surgical removal of the gallbladder.[5,6]
Ursodiol can dissolve selected small cholesterol stones and can help prevent stones during rapid weight loss, but it is used in specific clinical situations. Treatment decisions depend on symptoms, imaging, anatomy and the risk of complications.[2,5]
Can you follow a low-carb diet without a gallbladder?
Yes. Removing the gallbladder does not stop the liver from making bile and does not automatically require a permanently low-fat diet. After surgery, bile flows more continuously from the liver into the intestine instead of being stored and released in a larger pulse.
Immediately after surgery, smaller meals and a temporary reduction in concentrated fat may be more comfortable while the digestive system adapts. Fat can then be increased gradually according to tolerance and the surgeon’s instructions.
Two clinical studies found no meaningful symptom advantage from routinely prescribing a low-fat diet after laparoscopic cholecystectomy. In a prospective study of 83 patients, more than half reported a change in bowel habits after surgery, but the amount of dietary fat did not influence overall symptom improvement; bowel changes persisted at six months in 23%. A randomized study of 40 patients likewise found no significant symptom benefit from a routine low-fat diet.[7,8] Most people can return to a normal, individualized diet, including a low-carbohydrate diet.
Practical steps after surgery include:
- Start with smaller meals
- Increase dietary fat gradually rather than all at once
- Choose whole-food fat sources
- Avoid forcing added fats beyond appetite
- Adjust individual foods that repeatedly cause diarrhea, urgency or discomfort
- Maintain adequate protein and hydration
Persistent diarrhea after gallbladder removal can result from bile-acid diarrhea and may respond to specific medical treatment. It should not automatically be attributed to every source of dietary fat.
Rapid weight loss deserves a plan
Rapid weight reduction—whether from severe calorie restriction, bariatric surgery or intensive medical weight treatment—can increase gallstone and biliary-disease risk.[2,5,9]
GLP-1 medications deserve specific attention because they may be used at higher doses and for longer periods during weight treatment. A meta-analysis of 76 randomized trials involving 103,371 participants found 37% higher relative risk of gallbladder or biliary disease with GLP-1 receptor agonists overall. The absolute increase was 27 additional cases per 10,000 people treated per year. In the 13 weight-loss trials, the relative risk was 2.29.[10]
That does not mean effective weight loss should be avoided. It means clinicians should recognize the risk, ask about prior gallstones and biliary symptoms, and consider prevention or monitoring when the pace and amount of weight loss are substantial.
A structured plan should aim to:
- Avoid unnecessary starvation-level calorie restriction
- Include enough dietary fat to stimulate gallbladder emptying when the gallbladder is present and unobstructed
- Reduce refined carbohydrates and added sugars
- Preserve adequate protein and lean mass
- Investigate new biliary symptoms promptly
When gallbladder pain needs urgent attention
Typical biliary pain is usually felt in the upper-right or upper-middle abdomen and may spread to the back or right shoulder. It often builds steadily, lasts at least 15 to 30 minutes and may continue for several hours. When gallstones are suspected, abdominal ultrasound is the first-line test and detects gallbladder stones with greater than 95% accuracy.[6]
Seek urgent medical care for:
- Severe or persistent upper-abdominal pain
- Fever or chills
- Yellowing of the skin or eyes
- Dark urine or pale stool
- Repeated vomiting
- Abdominal pain with faintness, confusion or weakness
- Pain accompanied by difficulty breathing or chest symptoms
These signs can indicate acute cholecystitis, bile-duct obstruction, cholangitis, pancreatitis or another urgent condition.[5,6]
The takeaway
Dietary fat does not simply “cause gallstones.” Fat stimulates the gallbladder to do its job. During rapid weight loss, extremely low-fat, very-low-calorie diets can reduce gallbladder emptying and increase the conditions that favor stone formation. Randomized-trial evidence has found that diets containing more fat reduce gallstones compared with very-low-fat weight-loss diets.[1,2]
Once stones are present, however, dietary fat can trigger pain by making the gallbladder contract against an obstruction. That is a reason to seek a diagnosis, not proof that fat originally created the stone.
Low-carbohydrate eating can fit into gallbladder health before or after gallbladder removal. The best approach reduces sugar and refined starch, avoids unnecessary rapid starvation, provides adequate protein and uses dietary fat in amounts that support health, satiety and individual tolerance.
References
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Stokes CS, Gluud LL, Casper M, Lammert F. Ursodeoxycholic acid and diets higher in fat prevent gallbladder stones during weight loss: a meta-analysis of randomized controlled trials. Clin Gastroenterol Hepatol. 2014;12(7):1090–1100.e2. doi: 10.1016/j.cgh.2013.11.031. PubMed
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Tsai CJ, Leitzmann MF, Willett WC, Giovannucci EL. Dietary carbohydrates and glycaemic load and the incidence of symptomatic gallstone disease in men. Gut. 2005;54(6):823–828. doi: 10.1136/gut.2003.031435. PubMed Central
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National Institute of Diabetes and Digestive and Kidney Diseases. Gallstones. NIDDK
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European Association for the Study of the Liver. EASL Clinical Practice Guidelines on the prevention, diagnosis and treatment of gallstones. J Hepatol. 2016;65(1):146–181. doi: 10.1016/j.jhep.2016.03.005. Guideline PDF
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Ribas Blasco Y, Pérez Muñante M, Gómez-Fernández L, Jovell-Fernández E, Oms Bernad LM. Low-fat diet after cholecystectomy: Should it be systematically recommended? Cir Esp (Engl Ed). 2020;98(1):36–42. doi: 10.1016/j.ciresp.2019.05.009. PubMed
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Menezes HL, Fireman PA, Wanderley VE, Menconça AMMC, Bispo RKA, Reis MR. Randomized study for assessment of hypolipidic diet in digestive symptoms immediately following laparoscopic cholecystectomy. Rev Col Bras Cir. 2013;40(3):203–207. doi: 10.1590/S0100-69912013000300007. PubMed
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Yang W, Wu H, Cai X, et al. Weight reduction and the risk of gallbladder and biliary disease: A systematic review and meta-analysis of randomized clinical trials. Obes Rev. 2024;25(6):e13725. doi: 10.1111/obr.13725. PubMed
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He L, Wang J, Ping F, et al. Association of glucagon-like peptide-1 receptor agonist use with risk of gallbladder and biliary diseases: A systematic review and meta-analysis of randomized clinical trials. JAMA Intern Med. 2022;182(5):513–519. doi: 10.1001/jamainternmed.2022.0338. Full text
