1560s, to remove (a nut, etc.) from a shell, from shell (n.). The meaning to bombard with shells is first attested 1856. To shell out disburse (1801) is a figurative use from the image of extracting nuts. Related: Shelled; shelling.
There are 14 calories in 1 cup, slices (3 oz) of Nopales (Cactus Leaf), raw. You'd need to walk 4 minutes to burn 14 calories. Visit CalorieKing to see calorie count and nutrient data for all portion sizes.
It is a vegetable and a cup of cooked nopal has only 22 calories. What more could you ask for given all the nutrients it provides? We can incorporate nopal cactus as part of a healthy eating plan, but it is neither a panacea or the ultimate solution to your weight problem, let alone going is it going to cure diabetes. It is wise to consult with your doctor, especially before purchasing and consuming any type of supplements.