Perhaps, but since he did low carb, guaranteed 10-15lbs of that was water weight. I lost over 15lbs in my first week doing low carb, but almost all of it was water. About 4 days in starting the diet I was literally pissing every hour, and taking pretty much pure liquid shits every 2-3 hours for two days straight. My body was dumping huge amounts of excess water. I was way less puffy.
So he probably lost an actual 25-30lbs of fat instead of 40, which is an ok amount if morbidly obese, but not a rate that is sustainable for a long period of time.
Ive been averaging a loss of 2lbs/week for the past 10 months. I think I will be able to sustain it for another 2 or 3 months, but then will need to lower down to 1.5 as right now I can only eat 1700 cals on non workout days which is difficult. Most days I go over but I also dont eat back exercise calories.