Will I lose weight if start eating this way...?

Weight gain is caused by consuming more Calories than you burn off during the day. So theoretically, the only way to lose weight is to consume less and burn off more. What you eat is only really relevant because some foods metabolize faster than others, and for general health and energy. You may not lose weight by eating unprocessed foods, but you'll be a hell of a lot healthier. If you're sedentary, then your body is going to get used to running on zero energy. So you have to stay active. Eat fish and chicken (of the non-fried variety), and exercise.