6 pounds in one week without trying

Weighing in at the pool on January 10, the scale said 421lbs. a loss of 4lbs in 23 days. On the low end but a good start considering I did no swimming since December 18. But the bigger surprise came this Monday January 17 at my weigh in…416lbs another 5 pounds in one week! This seems too good to be true, but my girlfriend says this is normal considering I have improved my lunch and dinners the past week (by my standards). Will the big weight loss continue? My mom says my father could loose 20lbs a month with just eating healthy, so I could also be doing that with my new diet. We will see, but with this one idea I have had for years, 20lbs/month could be very realistic for a few months at least (don't count your eggs before they hatch).