For 16 days. I seem to have lost my appetite and overwhelming tiredness. Is this normal??
Yep, I have that. 
Along with nausea, diarrhea, anxiety, depression and lethargy. I keep hearing it gets better, but I'm 23 days in and so far, it's not better.
Same as Lynda basically - I'm almost 5 weeks in, currently on 100mg and with little to no appetite, waves of anxiety and depression, nausea etc.
From what I have seen in a lot of places, sertraline can take longer to work than other ssris.
I've begun to see little signs of brightness finally 
Well that gives me some hope then I'm not even at four weeks yet.