He lost 65lbs (starting from 240lbs looking at the indiegogo page) on a very high caloric deficit diet of 1000kcal/day, loosing an increasing 10%+ of his body w

He lost 65lbs (starting from 240lbs looking at the indiegogo page) on a very high caloric deficit diet of 1000kcal/day, loosing an increasing 10%+ of his body weight every month. Way higher than the usual 1,5-2% recommended to maintain most of your muscle mass. But I'm not even sure if the math makes sense here, using the bro-science 3500kcal/lb of fat ratio we get a required 2500kcal daily deficit. This kind of deficit seems really hard to reach (even factoring for some water/muscle loss that would reduce the required daily deficit), considering that no additional physical activities where added (again, recommended to maintain muscle mass when you are loosing weight). Need more details.