Consuming lettuce has little effect on stomach expansion. Leafy green vegetables, such as lettuce and cabbage, contain a carbohydrate called raffinose that produces gas. Some individuals lack the enzymes required to digest this starch. As a result, after eating lettuce, their stomachs may feel distended or bloated.
Within the digestive system, gas expands. As it does so, it might cause discomfort until the body breaks it down or eliminates it. Internal organs are not stretched permanently after consuming gassy foods. Rather, the gas pressure causes organs, such as the stomach, to experience a sensation of being stretched.