A low calorie diet can lower your metabolism. Regularly eating fewer calories than your body needs can cause your metabolism to slow down. Several studies show that low-calorie diets can decrease the number of calories the body burns by as much as 23%. So if you are watching your weight, controlling your calorie intake by incorporating low-calorie food is important, but even more important is to choose foods that will fill you up so you are not tempted by hunger and cravings between meals. So considering fibre levels and whether they are a complex carb, should be high up on your list.