Read the ingredients on those foods and you'll probably won't be able to pronounce them all. That fat free yogurt probably is loaded with sugar.
Eating fat does not make you fat, if you stay away from the saturated fats especially when they are combined with sugars, eating a little more fats from nuts and oils will not cause you to be fat. Your body needs fats to function properly
Have an apple and a few raw almonds for a snack. or some carrots and a little hummous.,
An orange, a banana, some strawberries, some sliced tomato and a little fresh mozzerella.
Stay away from the stuff that comes in a bag and is made at a processing plant.
If you eat real food, it's almost impossible to eat too much.