They are a good lo-cal treat. As whole, uncooked pieces they go through the GI pretty undigested (as others have said). So the dog enjoys a crunchy treat, but really does not get many calories out of it. The insoluble fiber (cellulose) prevents much starch absorption, so they are lo-cal for dogs. Now, the same is not true for say...rabbits....

Anyway, the vet I work with recommends them all the time for the pudgier canines. She also recommends unbuttered, unsalted, air-popped popcorn. Both are fine in moderation.

Big carrots cut in half are fine as long as they are chewed adequately.