**4. Gut-associated diseases**

Besides fatty liver and pancreatitis (discussed above), obesity is associated with increased risk of cholelithiasis (gall bladder stones) and gastroesophageal reflux disease (GERD).

### **4.1 Cholelithiasis**

About 90% gallstones are cholesterol stones while the rest are made of calcium bilirubinate, calcium complexes, mucin glycoproteins, or unconjugated bilirubin. Obesity and metabolic syndrome are two risk factors for the development of cholelithiasis, other factors being genetics, age, gender, parity, and presence of hepatitis C virus infection and chronic kidney disease [122]. Recent study by Su et al. [123] shows that obesity reduces the age of onset of gallstone formation. Energy-dense food such as increased consumption of refined carbohydrates and saturated fats with decreased intake of fiber, and medicines such as estrogen and progesterone can promote cholelithiasis [124]. Rapid weight loss of more than 1.5 kg/week can also promote gallstone formation [125].
