Yes. Of course it is better if you don't consume too much sugar. The effect of losing weight comes primarily from depleting your glucose stores and letting the body change to fat burning during the fasting periods. Certainly, you can optimize and accelerate your progress if you renounce sugar and ready made fast food largely. Doing physical exercise on a regular basis is also heavily recommended. The optional weekly challenges in the BodyFast app help you to live healthy and to reach your goals.