If you want a cold, milky coffee drink, I would suggest an iced coffee with milk. Request nonfat milk. Also make sure to request no classic syrup (this comes with iced coffees and teas) you can replace it with a sugar free syrup!
Of course skinny lattes are good ideas too, but just mentioning the Iced coffee because it has less milk and therefore less calories.
(I work at starbucks!
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