Honey, if you are referring to a boyfriend or a husband.....honestly, do you really want someone long-term who is going to be this judgmental and demanding? Don't you want someone who loves you for you? And is supportive?
I mean, not only should you NOT be doing this because someone else is demanding it....but why would you want to be with someone who would even do this in the first place? And it would be, I'd imagine, a horrible environment to be in to be trying to do a weight loss plan in.
Generally speaking, severe restrictions result in lowered metabolism, increased difficulty losing weight and ultimate gaining of even more weight.
Instead of fasting, why don't you check out some of the eating plans, like low-carb/Atkins, where you are not deprived of adequate calories but can still lose weight pretty darn fast?
Do this for you, not him. I say "ditch him"....and get someone who deserves to be with you.
deena