Don't peel. An apple with its peel provides almost twice as much fiber, 50 percent more vitamin A, and 25 percent more potassium as one without it. (Just wash the apple first.)
Peel. Most of the cuke's fiber comes from the seeds, and you won't lose too much potassium, either. That hard-to-wash-off waxy coating is there mainly to slow down ripening.
Peel. The texture of unpeeled carrots can be a turnoff, and peeling won't cost you much potassium, vitamin A, or fiber.
Don't peel. The flesh and the skin are packed with vitamins A and C, potassium, and fiber. If the fuzz is a deal breaker, try nectarines, which have the same nutrients and fiber.