I am puzzled as to why the scale has not budged for three weeks. I have been faithful in logging, and have had a calorie deficit of between 500 and 800 each day (protein about 27%, carbs below 15%); have been exercising 4-6 hours per week; drinking water - but staying stubbornly stuck at 165 lbs. The same regimen was producing 1-2 lbs of loss per week. The only difference is that for the last 4 weeks I have been exercising early in the morning instead of mid-morning. Can sleep changes really make that big a difference? And if so, will my body get used to this and start losing again?