Is it good to drink milk or banana milkshake after workout ? does it make you fat ?

Go cheap: The best post work-out drink is plain, old chocolate milk. No need to buy the expensive milk-like supplements (you can look it up.) as for milkshakes of any flavor, they will be high in fat and calories, and will be counterproductive, especially if you're working out to lose weight. But, i personally think some milk each day will generally be beneficial. Good luck.