You stop by your favorite organic coffeehouse, craving a deliciously hot latte or cappuccino. So, what’s the real difference between ordering a regular vs. a nonfat drink?

If you opt for a small size, made with nonfat milk instead of low-fat milk (the standard at many coffee bars), you’re looking at a difference of 20 to 30 calories, says Karen Collins, a registered dietitian in private practice and nutrition adviser to the American Institute for Cancer Research in Washington, DC. Buy a large latte or cappuccino, and there’s a 40- to 50-calorie difference.

“Fat content changes by about 3 to 5 grams,” she says. “Your choice of portion size actually has far more impact. Without changing the type of milk used, changing from small to large in portion size adds from 70 to 140 calories per serving, and ordering super-large sizes available at some places adds even more.

“The other big factor is whether you turn this coffee beverage into a dessert by adding goodies like mocha, whipped cream or caramel syrup,” Collins continues. “Making it a ‘dessert coffee’ adds 50 to 150 calories to a small, or 130 to 230 calories to a larger, drink. If you splurge on one of these drinks once a week or so, none of these differences is really significant. But if you drink one daily, these details can really add up and affect weight control and overall health.”