If weight loss is purely determined by calories in vs calories out, then what explains mathematically impossible results? For example, I'm pretty sure I only had about a 4,000 calorie deficit this week, which is a little over 1 pound lost. However, the scale said almost 4 pounds lost. It's not like I'm complaining, but I'm pretty sure that if I ate one really big meal, all those extra unexplained pounds would pile right back on. What gives?