How to fix it: A healthy amount of weight loss is a pound to two pounds per week. Research shows that people who lose a lot of weight very quickly are more likely to gain it back. (Just as you may have seen in the "Where Are They Now?" episodes of those weight loss shows.)
It's important to be patient and see each lost pound to be a huge achievement along the way. And remember to have ways other than the number on the scale to measure your progress, such as how your clothes are fitting or the number of inches you've lost. Think about all the other healthy improvements and benefits of running that you're seeing, including reduced stress, improved sleep, increased energy, and reduced risk of many diseases.