6 weeks and losing weight?!

Priscilla
So I've lost 5lbs in a little over a week. I usually struggle to lose any weight so this is rest surprising to me. I drink tonnes of water all the time so I don't think it's hydration, but I've had a bit of a decreased appetite but surely that would account for 5 whole pounds...
Should I be concerned? I'm just 6 weeks along now.