Baby food carrots are more concentrated, with 0.7 grams of fiber in 1 ounce, or 5.6 grams in a 1-cup portion. A cup of carrot juice, however, holds only a paltry 1.9 grams of dietary fiber. Continuum Health Partners lists carrots as one of the top 20 high-fiber foods in the American diet.
Abdominal distension refers to the swelling of the abdomen. The distension may be caused by either air (gas) or fluid collection. The accumulated substance causes an outward expansion of the stomach and waist beyond normal proportions.
Stomach hardening (and by that I think you mean distension of the abdomen) can be a serious condition. I would recommend seeing a primary care physician to ensure there is not a serious or life threatening process. As for what can cause the abdominal distension, there are many causes.