Dieting, exercising, losing weight but pants are fitting tighter?

I have cut out sugar and white flour. I'm eating nothing with any artificial ingredients. I've cut coffee and started with green tea. I have been doing this for about a month. I have been riding a stationary bike, boxing, and doing pilates. My has gotten higher and shapelier, so I don't know if that would explain my pants fitting the same as before. I have lost weight. On the scale, and in the mirror, I have definitely lost weight, especially around my waist, but I'm getting muffin tops in pants that fit me fine before I ever started all this. That doesn't make much sense to me. Can the muscular backside do that? Please help? This is really discouraging.