It's easy to be confused about what, exactly, makes up a single serving. Just because it fits into one bowl doesn't make it one serving, at least, not according to dietitians. In general, the serving sizes upon which diet recommendations are based are a lot smaller than we tend to think.
Most people serve themselves more than that, so they're really eating more than one serving.
Nutrition experts at UT Southwestern Medical Center at Dallas say restaurants make it even harder for people to judge portion size. At home, you can measure your servings. UT Southwestern nutrition experts say you should practice measuring at home to give yourself a good sense of what a serving really is. If you measure your food at home, you'll get used to how much you should be eating. Then, at a restaurant you can eyeball your plate and decide how much to eat at one time.