I'm 3 weeks post op and am down 21 lbs, which I'm thrilled about. But this week I'm really feeling fatigued and my weight loss has completely stalled, is this normal?

Yes.

I think most of us have stalled at 3 weeks. Your weight loss so far has been very good. I will loose a little weight each day & then won't loose any for 2 or 3 days. My weight will even got up a pound but then comes right back down. Hang in there. I think "stalls" are just the nature of the beast.

I lost count........relax.....they come and go and you will continue to lose...

Completely normal. Stay the course and it'lll come off little by little.

Take your measurements. Every time I stall I lose a lot of inches. It's like your body is rebalancing your weight. It will kick back in. Protein and water. Keep focused!