Is it possible to lose weight but eat still junk food?
You can loose weight by eating fewer calories. If you get all your calories from potato chips and ice cream but consume fewer than you burn you will loose weight.
Your goal should be to get healthier, not just loose weight. If better health is your goal than you should eat healthier foods as well.
If you eat it in small amounts and find healthier versions. Baked chips are better for you than fried, dark chocolate is full of antioxidants, and sugar-free cranberry juice is very good for purifying blood fat.