Want to decrease my calorie intake to 1200 a day, with exercise, and eat mostly whole and natural foods, will a diet pill accelerate my weight loss?

Exercise. There is no basis for thinking a pill will accelerate weight loss in a healthful way. You are on the right track with eating natural and whole foods, emphasizing a balance and avoiding saturated fats. Resistance, weights and exercise are a healthy way to lose weight while eating lighter.