Another way to look at calories is:

140 calories for a small raw jicama (about 12 ounces)
456 calories for a large raw jicama (about 2.6 pounds)

Those numbers are independent of dressings. And the numbers are different if the jicama is cooked.

1 cup, raw has 49.4 calories, 0% fat, 6.4g dietary fiber.

http://www.fitday.com/webfit/nutrition/All_Foods/Vegetables/Jicama_raw.html