what is the cause of excess gas after eating a meal?
The meal itself, some meals are more likely to cause more gas than others e.g high fat, protein meals, or those with lots of onions or cabbage. Also if you lack enzymes to digest beans or milk or have gastritis or Gerd or other diseases affecting digestion you might have these issue. Lastly if you are constipated.
Sometimes, they can be tolerated in smaller amounts. For example, three glasses of milk a day may cause an individual excessive gas, but limiting milk to one glass per day may cause no problems. Sometimes tolerance to certain foods can be acquired. Many people complain that adding fiber to the diet causes gas.