Confused! Depending on % lost, eat certain % less?

I apologize in advance if this sounds slightly stupid, but I was watching HBO's Weight of the Nation, and this part was kind of confusing to me:

http://www.youtube.com/watch?v=e26JKMpSNSo&feature=player_embedded


Here's the transcript of it if y'all don't want to watch the video:

"Individuals losing weight are not metabolically the same as they were before they lost weight. Consider two individuals, same gender, same age, exactly the same body weight, one of whom is at that body weight as a result of, let’s say, a 10 or 15 percent weight reduction, and the other who has been at that weight for their entire adult life. The weight-reduced individual will be requiring about 20% less calories per day, relative to what somebody of that weight who has never lost weight would eat, or eat 10% less and increase their physical activity by 10% in order to keep at that body weight.

If that reduced individual goes out to lunch with their friend, and they both order the same meal, that will represent a 20% overeating for the weight reduced individual; quite normal for the individual who is not in that state. 20% may sound as a little but 20% excess caloric intake a year will account for the inexorable weight regain. As far as we know, this phenomenon does not go away, so being successful for a year or two doesn’t mean that you are going to be able to go back to eating at the rate that would be appropriate for a person who had never lost weight."


So basically what they're saying is that if you lose 10-15% of your body weight, you'll require 20% calories less per day than someone of the same height and maintenance weight in order to maintain that weight. This doesn't make sense to me. How do they come up with these numbers?

I guess don't really believe in the set point theory. You see people on MFP who have lost 100+ lbs, some even 50% of their bodyweight and are maintaining it. Does that mean that these people are eating ≥50% less (since for a 10-15% loss they were saying someone needs to eat 20% less) than someone of their same height, build, and maintenance weight who has been that weight their entire adult life? Perhaps, but I don't think so looking at people's food diaries on MFP for example (since people try to be at or above 1,200 kcal at minimum, and many people eat more than that at their maintenance weight trying to match their TDEE). I'm just so confused by this.

Also, I think weight training could modify this, but that effect wouldn't be significant enough to off-set it, since we're not all body builders and don't necessarily gain a significant amount of muscle. This is also directly contradicting the "eat more to lose weight" idea that people follow.

I can't even wrap my brain around it, and honestly this set point theory is the most frustrating to me because they make people like me think that they're destined to be a certain weight now even if they haven't been overweight for the majority of their lives. Sorry, I'm ranting, and I'm sure there's some truth to the above, but I just can't reconcile that with how things actually seem to be (if you look at people who have lost weight and are keeping it off). People aren't eating 20-60% less in calories than someone of the same height and weight who has never been overweight, even if they've lost that percentage of weight. I also refuse to believe that the body can't change or adapt over time. For example, if you maintain for 10 years, I'm sure your setpoint does reset to a certain degree.

What do y'all think? Do we have any experts in the house who can give us some opinions? Does anyone speak from personal experience? All opinions welcome, just be nice and polite to everyone! Thanks!