I have been fasting 23 hours a day for almost a year now for weight loss purposes. I know not to do this during shabbat, chagim, and rosh chodesh but was wondering whether it is problematic during Ramadan? Should I bedavka shift my hour of eating to a time during the day during Ramadan to avoid mirat ayin and the like?
Also, would it be appropriate to try to elevate this weight loss method into further kedusha by not drinking either on Mondays and Thursdays and accepting onto myself a voluntary fast?
You are not fasting because of Ramadan, rather because of your own health reasons. It should not be an issue of maris ayin, because by fasting you are not doing anything, but only abstaining from eating, and it isn’t because of the Muslum practices.
Regarding the Monday and Thursday aspect, you don’t have to, but if you would like to, and you will indeed make sure that you don’t mistakeny eat, I don’t see why you shouldn’t. There is just one drawback with doing this. Whenever someone does something that others are not doing, he has to be careful that this practice doesn’t subtly make him feel that he is better than everyone else, and cause him haughtiness. If indeed you do decide to do this, make sure that when you start fasting that you make sure to say that it is bli neder. One other point, accepting a volentary fast has to specifically be done befoire mincha the day before the fast.