Thats Normal.
As an athlete we see that frequently in the Gym. Ladies feeling faint/fainting and Muslim men during Ramadan also. Low blood sugar I guess.
If you wish to loose weight stop the carbs. White bread,rice,potatoes, French fries...eat meat and salads.etc.It will just melt off you.You are producing to much estrogene....males breasts soon
Good Luck.
In my opinion your medical should not have been pulled until the FAA or whoever received three agreed opinions one of which should of been a dietitians report.It sounds like you were starving yourself and coupled with stress your bodies reaction was fainting.
Currently it should be regulated that it takes more than one opinion three at least to invalidate a medical(grounding a pilot/end of income).That is a very ,very serious action.The power of these decisions leans to far over to the medical side and some doctors,not all, do make mistakes and at the end of the day ,are only human.Many will disagree ,but there are plenty of doctors who should have there licenses revoked as well and have.It is a debate we should have.Of course there are obvious reasons for invalidation,but some are dubious.