For me, when I start a new diet or exercise plan my body decides I have obviously gotten into some hostile situation where food is no longer available. Instead of burning stored fat, it clings to each molecule because OMG WE MAY NEVER BE FED AGAIN. It can take a week or two for my body and metabolism to chill out and realize that yes, we can burn fat and get skinny. All systems go!
According to MIT, a normal range of weight loss is 2 to 3 pounds per week. Maybe you lost more than that. Awesome but remember you shouldn't keep up that rate for too long. Maybe you lost less than 2 pounds. That's fine! Dieting can really confuse your body. Eventually, if you stick with your plan, you'll see results.
This week's leaders aren't necessarily next week's. A bad first week doesn't equal long term failure. Now grab a carrot and head out for a run!