Is there any dissymetry of lift in the forward flight of the helicopter after applying the cyclic control?

Dear friends,

I was curious about the time varying loads on the helicopter blades in the forward flight. After reaching lots of books and documents, I came to know that some control (cyclic) is applied to take care of the dissymetry of lift in the forward flight. My question is, if the dissymetry of lift is eliminated by applying the cyclic control or by blade flapping (whatever), then why the load should vary with time for the 90 and 270 position of the blade? Can anybody explain this? Please let me know the justification. I am really curious about it. 

Thanks

Pratik