Depending on where you buy a milkshake from, you may be consuming about 500 calories, 330 mg of sodium and 70 grams of sugar in a small-size cup (12 fl. oz.). A milkshake mix – dry, not chocolate – has about 330 calories, 50 grams of sugar and 780 mg of sodium. Mentally prepare to spend about an hour running on a treadmill to burn the calories.