Is it true that for obese men, doctors will recommend a strict 800 calorie diet but wont with obese women? if so, why?

I don't think so: The key to weight loss for men or women is reducing calories long-term. Men usually burn more calories per day than women, assuming similar levels of activity and similar body mass. Every individual's daily calorie needs are different, but to lose weight, one must keep reducing calories until the weight starts coming off. If weight is stable, it means the body still has enough calories to keep it.

Depends on Doctor.: It's not a universal fact that doctors prescribe 800 calorie daily meal plans for men or women trying to lose weight. Personally, I think that's too few calories, and I'd always rather people eat some more healthy calories and exercise in order to lose weight.