The World Health organisation states:
Health is a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity.
According to that definition I'd guess we're unhealthy
I think if you are okay to conceive but you aren't as healthy/fit/good weight as you should be it could delay conception a bit but judging by the horrid people i see at work who smoke crack, eat a bad diet and do not take care of themselves - they seems to be very fertile!!!