Grains

I've met quite a few health professionals who avoid grains.  I can't say that I completely understand this. 

I must admit that I've noticed that when people are trying to lose weight, heal inflammation in the body or get rid of the flu (or any upper respiratory illness); eating sugars or any carbohydrates are always counter-productive.  If I'm sick, I stay far away from all grains and sugars.  When I am in good health, however, I do eat grains as long as they are organic whole grains (and I don't mean in bread) and I will sweeten things with maple syrup (the REAL stuff, NOT the Mrs. Butterworth imitation junk), honey (raw) or fresh pressed organic fruit juice. 

I've always advised against white flour and white sugar though.  I've avoided them for years since they have no health benefits at all.  Both tend to make me ill anyway.

I welcome any commentary on why people have this belief that grains are so bad.  I'm genuinely curious and open to the fact that there may be something that I don't know.