Under normal physiological conditions, after people consume fatty foods, the duodenum secretes a hormone called cholecystokinin, which causes the gallbladder to contract. Cholecystokinin can cause the gallbladder to contract vigorously in a short period, allowing bile to be expelled from the biliary duct to participate in the digestion of fats. Bile contains bile salts, which can activate lipase to help emulsify fats, making fat droplets smaller and aiding in the digestion and absorption of fats. In patients with chronic cholecystitis or cholelithiasis, the gallbladder is inflamed and highly sensitive to pain. If excessive fat is consumed at this time, more cholecystokinin is secreted, causing the gallbladder to contract strongly and worsening the gallbladder inflammation, leading to more severe edema and congestion. Under the push of gallbladder contraction, stones in the gallbladder can enter the bile duct, causing a blockage that prevents bile from being easily discharged, resulting in severe biliary colic. Therefore, patients with chronic cholecystitis and gallstones should eat less greasy food to avoid acute attacks or pain of cholecystitis and cholelithiasis.