The reasons why the right upper abdomen is bigger than the left upper abdomen include uneven fat accumulation, chronic hepatitis, chronic enteritis, and intestinal space-occupying lesions, etc. The right upper abdomen is bigger than the left upper abdomen. 1. Uneven fat accumulation: lying on the right side immediately after eating, in the long run will lead to uneven fat accumulation on the abdominal wall, the right side of the abdominal accumulation is more serious, there will be a right upper abdomen is slightly larger than the left upper abdomen. 2. Chronic hepatitis: chronic hepatitis caused by cirrhosis in the early stage, the liver is enlarged, full, there will be a right upper abdomen than the left upper abdomen. 3. Chronic enteritis: chronic enteritis can cause abdominal pain, intestinal swelling and gas production, causing the right abdomen to swell, resulting in the right upper abdomen is larger than the left upper abdomen. 4. Intestinal space-occupying lesions: such as intestinal polyps, tumors and so on. It is manifested as a localized mass, which makes the right upper abdomen slightly larger than the left upper abdomen. If the right upper abdomen is enlarged or other uncomfortable symptoms, it is recommended to consult the doctor as soon as possible for regular treatment, so as not to delay the condition.