I smoke the new growth on my vegging plants. Fan leaves can be smoked but it isn't recommended. Better to consume (eat, juice, cook with) them than to smoke them. New growth (top 2 inches of the growing shoot) will have a serious effect depending on your tolerance level. If you have no THC in your system you will know what I'm talking about. If you are accustomed to smoking lots of bud then you will not notice any effect.
M.