It is realistic, but I really doubt that it is a healthy thing to lose that much weight in such a short period of time, and that it would be a long lasting results. After all, when losing weight it is best to be gradual in order to let the body accomodate to the new weight, and make those results more long lasting. I have personally lost 25-30 pounds in 4 weeks with minor tweeks in my diet, so it is well plausible to lose 37 pounds with a very restrictive diet.