happyhormones
No, because things like artificial sweeteners upset the endocrine system which is the system which controls weight. Being overweight means that your endocrine system is profoundly out of balance, and things that cause the endocrine system to become unbalanced are refined
Sugar and refined carbohydrates; artificial sweeteners, alcohol, heated fats; and all medications to a greater or lesser extent may upset this delicate system. Therefore if you want to fast, you may only want to lose weight, but if by losing weight you continue to interfere with your endocrine system, you are not going to achieve a lasting benefit, as you need to balance this system above all in order to achieve a lasting healthy weight. So ditch the sweetener! If you feel you must use something to sweeten your tea, then raw unheated honey in small quantities is not so bad, and fructose in small quantities, while it is a refined product (so should be used in moderation) does not have a detrimental affect on the blood
Sugar so can be used without too much concern. But really sweeteners should not be used under any circumstances. Good luck!