If I drink anything other than water I do not get the same results, but I do not fast for weight loss. It may be good if your purpose is just for losing weight. I do not really know. I fast for health reasons and I can tell that my results are much better with plain water. I also fast for spiritual reasons and to hear from God in which case I have found that God will answer if I am doing the best I can in seeking Him with prayer and fasting which may not always be a strict water fast. Hope this helps.
Rainy