Cholecystitis, or inflammation of the gallbladder, is driven by a mix of metabolic, hormonal, dietary, genetic, and situational factors, most of which trace back to one central event: something blocks the gallbladder from draining properly. Gallstones lodged in the gallbladder neck or cystic duct are the trigger in the vast majority of cases, and many of the risk factors below are really risk factors for forming those stones in the first place. But a meaningful minority of cases happen without any stones at all, particularly in critically ill patients, which means the full risk picture is broader than gallstones alone.
How Gallstones Set the Stage
Understanding why cholecystitis develops starts with what happens physically when a stone gets stuck. In acute calculous cholecystitis, a gallstone becomes impacted in the gallbladder neck or cystic duct, trapping bile inside. The gallbladder keeps secreting fluid but cannot empty, so pressure climbs. That rising pressure damages the wall, triggers inflammation, and if left untreated can progress to gangrenous changes, focal wall death, and even perforation.1PubMed. Improving Diagnosis of Acute Cholecystitis with US: New Paradigms Most risk factors for cholecystitis work upstream of this moment, by making gallstone formation more likely. A smaller group of risk factors act on the gallbladder itself, impairing its ability to contract and empty even when no stone is present.
Obesity and Insulin Resistance
Excess body weight is one of the strongest and most consistent risk factors. The connection runs through the liver: central abdominal fat is closely linked to insulin resistance, which in turn increases the amount of cholesterol the liver secretes into bile.2PubMed Central. Obesity and Gallstones When bile becomes oversaturated with cholesterol, crystals form, clump together, and eventually become gallstones. Measures of central fat distribution tend to predict gallstone risk better than overall body weight alone, because visceral fat around the abdomen is the type most tightly linked to the metabolic disruptions that change bile composition.
Insulin resistance does more than just change bile chemistry. Research has shown that it independently impairs gallbladder motility, meaning the gallbladder cannot contract and empty as effectively.3PubMed. Insulin resistance causes human gallbladder dysmotility A sluggish gallbladder lets bile sit longer than it should, giving cholesterol crystals more time to nucleate and grow. This dual mechanism, more cholesterol going in and less bile flowing out, explains why people with metabolic syndrome and type 2 diabetes face elevated risk even when they are not severely overweight.
The Paradox of Rapid Weight Loss
If obesity raises the risk of gallstones, you might expect that losing weight would lower it. In the long run it does, but in the short term, rapid weight loss is itself a potent trigger. When the body burns stored fat quickly, it mobilizes large amounts of cholesterol into bile, and the gallbladder often contracts less frequently because the person is eating far less. Those two changes create prime conditions for stone formation. One prospective study of patients who had gastric bypass surgery found that about a third developed new gallstones within six months, despite having a normal gallbladder scan at the time of their operation.4PubMed. Gallstone formation after rapid weight loss: a prospective study in patients undergoing gastric bypass surgery for treatment of morbid obesity
Rates vary across studies and surgical techniques. A randomized trial comparing different bariatric procedures reported an overall gallstone rate of about one in ten patients afterward, and found that patients who lost excess weight faster were significantly more likely to develop stones.5PubMed. Cholelithiasis after bariatric surgery, incidence, and prophylaxis: randomized controlled trial Broader literature reviews put the range at roughly 10 to 38 percent after bariatric surgery, with a corresponding increase in biliary complications including cholecystitis.6PubMed Central. Prevention of Gallstones After Bariatric Surgery using Ursodeoxycholic Acid: A Narrative Review of Literatures This is why many surgeons prescribe ursodeoxycholic acid for months after weight-loss surgery to thin out the bile and lower the chance of stone formation. Crash diets and very-low-calorie programs carry similar risks even without surgery, though they have been studied less rigorously.
Sex Hormones and the Gender Gap
Women develop gallstones and cholecystitis at significantly higher rates than men, and estrogen appears to be a central reason. Estrogen increases the amount of cholesterol the liver pumps into bile, pushing bile toward supersaturation.7PubMed. Gender and gallstone disease This explains why pregnancy, oral contraceptives, and hormone replacement therapy all amplify gallstone risk. In national surveys, the gender gap in gallstone disease is substantial: among women, total estimates of gallbladder disease are roughly double or more what they are in men of the same age and ethnic background.8PubMed. Prevalence and ethnic differences in gallbladder disease in the United States
The risk is highest during the reproductive years and during periods of hormonal change. Multiple pregnancies compound the effect, because each one means another extended period of elevated estrogen. After menopause, the gender gap narrows somewhat, but women who take hormone replacement therapy maintain the higher risk. Progesterone, the other major sex hormone in pregnancy and certain contraceptives, compounds the problem by slowing gallbladder contractions, giving cholesterol-laden bile more time to form crystals.
Ethnicity and Genetic Susceptibility
Gallstone prevalence varies dramatically across ethnic groups, and genetics explain a meaningful share of that variation. In the United States, a large survey found that Mexican American women had the highest rates of gallbladder disease at roughly 27 percent, compared with about 17 percent for non-Hispanic white women and 14 percent for non-Hispanic Black women.9PubMed. Prevalence and ethnic differences in gallbladder disease in the United States Among men, non-Hispanic Black men had the lowest prevalence at about 5 percent, while white and Mexican American men were similar at around 9 percent. The gender-specific nature of these ethnic differences is striking: among men, the gap between Mexican American and white participants is essentially zero, but among women it is large. That pattern suggests the genetic influence interacts with hormonal factors in ways researchers have not fully untangled.
Globally, Native American and Indigenous populations in the Americas carry the highest burden. Gallstones affect over 15 percent of adults in Europe and 25 to 30 percent of Hispanic populations in Central and South America.10PubMed. Genetics of biliary lithiasis from an ethnic perspective Genetic factors are estimated to account for about a quarter to a third of total gallstone risk in European populations, but in Hispanic populations with Indigenous American ancestry that figure may rise to somewhere between 45 and 65 percent. One well-studied gene variant, in ABCG8, promotes gallstone formation by ramping up the amount of cholesterol the liver secretes into bile while reducing dietary cholesterol absorption.11PubMed Central. Risk of gallstones based on ABCG8 rs11887534 single nucleotide polymorphism among Taiwanese men and women This variant and others like it are more common in the populations where gallstones are most frequent.
Diet, Physical Activity, and Sedentary Behavior
What you eat matters, though the picture is more about dietary patterns than any single food. Diets high in refined sugars, fructose, fast food, and saturated fat, combined with low fiber and low vitamin C intake, consistently track with higher gallstone risk. Diets rich in fiber, olive oil, fish, vegetable protein, fruit, and moderate coffee and alcohol consumption appear protective.12PubMed Central. The Role of Diet in the Pathogenesis of Cholesterol Gallstones The mechanism circles back to bile composition and gallbladder function: high-sugar, high-fat diets promote cholesterol supersaturation of bile, while fiber helps maintain the balance of bile acids that keep cholesterol dissolved.
Physical inactivity is an independent risk factor. Large cohort studies have found that prolonged sitting is associated with increased gallstone risk regardless of how much exercise a person gets separately. People who sat for ten or more hours per day had a roughly 15 percent higher risk of gallstones compared with those who sat fewer than five hours, even after adjusting for other factors.13PubMed Central. Physical activity and risk of cholelithiasis: a narrative review Separately, people who were physically inactive had about a 22 percent higher risk than those who were most active, with a clear dose-response trend.14PubMed. Prolonged sitting increases the risk of gallstone disease regardless of physical activity: a cohort study The likely explanation is that movement stimulates gallbladder contraction and promotes better bile turnover, while sitting allows bile to stagnate.
Medications That Shift the Balance
Several commonly prescribed drugs increase gallstone or sludge risk by altering bile chemistry or gallbladder motility. The most relevant ones include:
- Somatostatin analogs (e.g., octreotide): Used for conditions like acromegaly and neuroendocrine tumors, these drugs impair gallbladder emptying and change bile composition. Roughly a quarter of patients on long-term therapy develop gallstones or sludge within the first 18 months.15PubMed Central. Acute cholangitis: a state-of-the-art review
- Ceftriaxone: This common antibiotic is excreted heavily into bile, where it can form insoluble calcium precipitates that mimic sludge. Biliary sludge has been reported in a large fraction of patients receiving the drug, though the sludge usually resolves after the antibiotic is stopped.16PubMed. Drug-induced gallbladder disease. Incidence, aetiology and management
- Fibrate lipid-lowering drugs: Clofibrate and related drugs like fenofibrate inhibit an enzyme involved in bile acid synthesis, resulting in cholesterol-supersaturated bile.17PubMed Central. Acute cholangitis: a state-of-the-art review
Total parenteral nutrition, or TPN, where all nutrition is delivered intravenously and the gut is bypassed, is another well-documented trigger. When a person is not eating, the gallbladder receives no signal to contract. Bile stagnates inside it, leading to sludge buildup that can progress to stones over time.18PubMed. Does total parenteral nutrition induce gallbladder sludge formation and lithiasis? Animal studies confirmed that this stasis occurs regardless of what caloric source is used in the TPN formula, and that the problem is specifically the lack of gallbladder emptying rather than any change in cholesterol saturation of bile.19PubMed. The effect of intravenous fat and total parenteral nutrition on biliary physiology Patients on TPN can also develop full-blown acalculous cholecystitis.20PubMed Central. Cholecystokinin prophylaxis of parenteral nutrition-induced gallbladder disease
Acalculous Cholecystitis in Critical Illness
About 5 to 10 percent of acute cholecystitis cases occur without any gallstones. This form, called acalculous cholecystitis, disproportionately strikes patients who are already critically ill in intensive care units. The proposed mechanisms center on gallbladder ischemia (reduced blood flow to the gallbladder wall), bile stasis from fasting and sedation, and systemic inflammation from conditions like sepsis or pneumonia.21PubMed Central. Acute acalculous cholecystitis in hospitalized patients in intensive care unit: study of 5 cases Major trauma, burns, prolonged mechanical ventilation, and major non-biliary surgery are all associated with this form. It tends to be more dangerous than the stone-caused variety because it often occurs in already-debilitated patients and can progress to gangrene more quickly.
A study of very elderly patients with acute cholecystitis found that severe disease grading was dramatically associated with death, and that prior history of biliary disease and a high surgical risk score were linked to developing severe cholecystitis in the first place.22PubMed Central. Acute Cholecystitis in Very Elderly Patients: Disease Management, Outcomes, and Risk Factors for Complications This underscores that age, frailty, and cumulative biliary history compound each other. In older adults with previous gallbladder problems, even a relatively minor acute illness can tip into dangerous cholecystitis.
The Gut Microbiome Connection
An expanding body of research points to the community of bacteria in the gut as an underappreciated player in gallstone formation. Animal experiments and human studies have found that certain bacterial populations can shift bile acid chemistry in ways that favor cholesterol crystallization. Bacteria enriched in Desulfovibrionales, for instance, promote gallstone formation through multiple routes: they increase production of secondary bile acids in the gut, influence liver enzymes that regulate bile acid production, and ultimately push more cholesterol into bile.23Nature Communications. Gut microbiota promotes cholesterol gallstone formation by modulating bile acid composition and biliary cholesterol secretion
Other research has identified specific bacterial enzymes called bile salt hydrolases, produced by common gut bacteria like Bacteroides and Lactobacillaceae, that break down cholesterol-solubilizing bile acids too aggressively. In people with gallstone disease, these bacteria are more abundant, and the resulting bile acid profile shifts toward types that are worse at keeping cholesterol dissolved.24PubMed Central. Gut Microbiome Dysbiosis Promotes Gallstone Formation via Bile Acid Metabolic Disorder: A Multiomics Study The gastrointestinal microbiome regulates bile acid metabolism through several overlapping pathways, including direct effects on the liver’s primary bile acid synthesis and indirect effects on intestinal cholesterol absorption.25PubMed Central. Gastrointestinal microbiome and cholelithiasis: Current status and perspectives
This research is still relatively early-stage. Nobody yet has a clear clinical tool for measuring gallstone-related microbiome risk, and there are no proven probiotic interventions that prevent stones. But the microbiome connection helps explain why people with otherwise similar diets and body weights can have very different gallstone experiences. It also opens the possibility that the protective effects of fiber, certain fats, and other dietary factors might work partly through the microbiome rather than only through direct changes in bile chemistry.
Conditions That Predispose to Pigment Stones
Not all gallstones are cholesterol stones. About 20 percent are pigment stones, made largely of calcium bilirubinate, and they have their own set of risk factors. Anything that increases the breakdown of red blood cells raises bilirubin levels in bile, promoting pigment stone formation. Sickle cell disease is one of the most recognized triggers, and prophylactic gallbladder removal is sometimes recommended for these patients because the lifetime risk of symptomatic stones is so high.26PubMed Central. Gallstones Other hemolytic conditions, chronic liver disease (especially cirrhosis), and biliary infections carry similar risk for pigment stones. The underlying pathway is different from cholesterol stones, but the end result, an obstructed gallbladder prone to inflammation, is the same.
Biliary sludge, a thick mixture of cholesterol crystals, calcium salts, and mucus, is generally considered the precursor to both types of gallstones. Conditions that promote sludge formation, such as prolonged fasting, TPN, pregnancy, and certain medications like ceftriaxone, create a stepping stone toward stone formation. In many patients, sludge resolves on its own once the triggering condition is removed. In others, it persists and hardens into a stone that can lodge in the cystic duct and cause cholecystitis.
How Risk Factors Stack Up Together
Cholecystitis risk is cumulative rather than dominated by any single factor. A woman who is overweight, takes oral contraceptives, eats a high-sugar diet, and has a family history of gallstones faces dramatically higher risk than someone with just one of those factors. This stacking effect is clinically important because it means that modifying even one or two risk factors can meaningfully lower overall risk, even when genetic susceptibility cannot be changed.
The factors with the largest individual effect sizes tend to be the ones people can do the least about: ethnicity, sex, and age. But the modifiable factors, body weight, diet quality, physical activity, and awareness of medication-related risk, are collectively potent. For someone who already has silent gallstones, the calculus shifts further: rapid weight loss, prolonged fasting, and certain new medications become acute triggers for cholecystitis rather than gradual contributors to stone formation. In that context, the most practical risk factors to understand are the ones that turn a quiet stone into an emergency.
Age and Prior Biliary Disease
Gallstone prevalence increases steadily with age, and so does cholecystitis risk. Bile becomes more lithogenic over time as the liver’s cholesterol-to-bile-acid ratio shifts, gallbladder motility decreases, and cumulative exposure to other risk factors adds up. By age 60, a large fraction of the population has gallstones, though most remain asymptomatic. A previous episode of biliary colic or known gallbladder sludge significantly raises the probability that cholecystitis will eventually occur, which is why physicians often discuss elective cholecystectomy with patients who have had symptomatic episodes.
In very elderly patients, the consequences of cholecystitis are more severe and the presentation is often atypical, with less pronounced pain and fever. Studies of acute cholecystitis in patients over 80 show that a prior history of biliary disease roughly tripled the odds of presenting with severe-grade cholecystitis.27PubMed Central. Acute Cholecystitis in Very Elderly Patients: Disease Management, Outcomes, and Risk Factors for Complications Diabetes, which is itself more common with age, compounds the problem by worsening gallbladder motility and impairing immune defenses against the infection that can accompany cholecystitis.