I have gained 20 pounds in 4 months, all in my waist. My waist expanded 6 inches in those 4 months. I went from 240 pounds to 140 pounds over the course of 6 years by diet and exercise. I maintained 140 pounds for almost a year. I had a partial hysterectomy last year, and still maintained the 140 pounds. This current weight gain has been very rapid. I am still excercising (running, biking, strength training) every day but continue to see my waistline expanding. I have been tested for thyroid problems, had cortisol level drawn and even tried phentermine. I keep gaining. I only sleep 4 hours per night because I work two jobs. This is fairly recent. Could lack of sleep alone cause me to regain my weight? Anybody experience this? Please help! I worked way too hard to lose those 100 pounds.