If I ate a sandwich at only 176 calories, why do I still feel so fat after eatin!

I get that feeling sometimes myself. A big part of that is actually the carbohydrates. Things high in fiber, protein and carbohydrates usually give you that "full" feeling quicker. A salad has very little (depending on the type of salad) to no carbs and even after eating a large bowl can leave you feeling somewhat hungry. With a salad you are filling up on volume. Depending on the sandwich, it can have a significant amount of fiber, carbs, etc. I can have a single muffin sometimes and get that fat feeling. Especially something like a chocolate muffin with a lot of carbs in it in the form of sugar and starch. There's extensive information on these "diet facts" but hopefully this answered your question!