What are Gallstones?
Gallstones (choleliths) are solid formations that develop inside the gallbladder — a small organ beneath the liver that stores bile. Bile is a fluid needed to digest fats, but when its composition changes, it can lead to cholesterol supersaturation and crystal precipitation.
Gallstones may be:
- Cholesterol stones (the most common, 80–85%)
- Pigment stones (due to bilirubin)
- Mixed stones (a combination of both)
In most cases, stones do not cause symptoms. However, when they move and obstruct the cystic duct or the common bile duct, they trigger a biliary colic: acute pain in the right upper abdomen.
How Common is Gallstone Disease?
Gallstone disease is one of the most common digestive conditions. In Europe and the U.S., it affects about 10–20% of the population; in Greece it is estimated at around 12–15%.
Women are affected 2–3 times more often, mainly due to estrogen, pregnancy, and use of contraceptives.
Risk Factors
The formation of gallstones is multifactorial. Among the main risk factors:
- Obesity (especially abdominal/visceral obesity)
- Female gender & hormonal changes
- Age over 40 years
- Type 2 diabetes and metabolic syndrome
- Rapid weight loss or fasting
- Family history of gallstone disease
- Diet low in fiber and high in fats
New Evidence: Relative Fat Mass (RFM) and Gallstones
A recent 2025 study published in Scientific Reports (Nature Publishing Group) highlighted for the first time a strong association between the Relative Fat Mass (RFM) and the risk of developing gallstones.
The study analyzed data from 7,978 adults from the U.S. National Health and Nutrition Examination Survey (NHANES, 2017–2020). Of them, 828 had a history of gallstones.
Key findings:
- For each increase of 1 unit in RFM, the odds of gallstones increased by 9%.
- The risk threshold was identified at RFM = 40.99.
- RFM showed better predictive accuracy than BMI — with AUC of 69.7% vs 63.9%.
- The positive association remained across all subgroups (gender, age, diabetes, hypertension).
- Women showed even higher risk increase per RFM unit (OR 1.11).
Pathophysiological Mechanism
The link between obesity and gallstones is not coincidental. Increased fat mass, especially around the abdomen, affects cholesterol metabolism and gallbladder function:
- Bile cholesterol supersaturation: enhanced hepatic lipogenesis leads to overproduction of cholesterol which precipitates.
- Reduced bile acid synthesis: obesity suppresses activity of the enzyme CYP7A1, which converts cholesterol into bile acids.
- Gallbladder dysmotility: insulin resistance impairs release of cholecystokinin (CCK), causing bile stasis.
- Chronic inflammation: increased cytokines (IL‑6, TNF‑α) lead to gallbladder wall inflammation and fibrosis.
- Altered gut microbiota: certain bacteria change bile salt composition and promote stone formation.
Clinical Implications
This study brings a fresh perspective to gallstone diagnosis and prevention. The use of RFM index (based simply on waist circumference and height) allows physicians to identify high-risk individuals early.
For gastroenterologists, RFM may serve as:
- A predictive marker in patients with metabolic syndrome or diabetes
- A criterion for inclusion in preventive ultrasound screening
- Part of a preventive metabolic check-up in patients with abdominal obesity
Prevention & Nutritional Management
Prevention of gallstone disease relies on stable weight control and balanced diet.
Dietary Recommendations
- Avoid fried foods, processed meats, full‑fat dairy.
- Choose foods rich in fiber — fruits, vegetables, whole grains.
- Prefer olive oil over animal fats.
- Have small, frequent meals.
- Avoid skipping meals and don’t follow crash diets.
Lifestyle Recommendations
- Maintain a healthy BMI (18.5–24.9).
- Engage in regular physical activity (≥ 150 minutes per week).
- Control blood sugar, blood pressure, and lipid profile under medical guidance.
- Limit alcohol and smoking.
When to Seek Medical Evaluation
Seek immediate medical advice if you experience:
- Severe right‑sided abdominal pain after a fatty meal
- Nausea, vomiting, or fever
- Yellow discoloration of skin or eyes (jaundice)
- Persistent loss of appetite or bloating
Ultrasound remains the most reliable, painless, and cost‑effective method for diagnosing gallstones.
Frequently Asked Questions (FAQ)
- How do I know if I have gallstones?
Typical signs are right‑side abdominal pain, bloating, nausea or vomiting after fatty meals. Only an ultrasound gives a definitive diagnosis. - Can gallstones pass spontaneously?
Most gallstones do not pass on their own. Symptomatic cases often require cholecystectomy. - Does obesity affect gallstone risk?
Yes. Increased Relative Fat Mass (RFM) significantly raises the risk of gallstone formation. - How can I prevent gallstones?
Maintain healthy weight, follow a balanced diet, and have regular medical check‑ups.
Conclusion
Relative Fat Mass (RFM) emerges as a strong predictive marker for gallstone disease, outperforming the classic BMI in diagnostic accuracy. Maintaining healthy weight, proper nutrition, and timely medical follow‑up are the most effective “tools” to prevent disease complications.
“Gallbladder health reflects our overall metabolic balance.” — Theodoros Argyropoulos, M.D., M.Sc., Ph.D.
