the infamous three-week stall, right on time! Almost all of us experience that - if you do a search on it on this site, you will find over 17,000 posts on it (and no, I am NOT kidding).
Just stick to your program and stay off the scale for a few days if you have to. It WILL break - it always does. They typically last 1-3 weeks. And just so you know, you're likely to hit a few of these along your journey. Just hold tight and stick to your plan...
