A starch is a complex carbohydrate slowly converted to glucose and absorbed into the bloodstream during digestion. Some types of squash, including acorn squash and butternut squash, are high in carbohydrates and are considered starches. Other types of squash are not.
Zucchini and summer squash are some examples of squashes that are not starches. The squashes that are considered vegetable starches have a significant amount of complex carbohydrate calories and a much smaller portion of calories from sugars. Too many starchy vegetables, including starchy squashes, can cause problems for diabetics and people on certain types of low-carb diets, according to SFGate.