I can not put any science behind it. You'd think a pound of fat is a pound of fat and all stored fat, regardless of how long it's been on the body, would burn or be consumed for energy at the same rate.
What I've observed is that you can take 2 people. One who put-on 50 pounds over the last couple years, and another person who has been fat all their lives. For reasons that elude my explanation and to which I can not reference any science to explain, the person who put the weight on over the last couple years will shed their fat faster...while the fatty-4-life will have a much MUCH tougher time. I'll ask my nutritionist about this when next I see him.
I do burn a LOT of calories, I can average 15-18 hours of exercise per week sometimes. I have lost fat at approx. .7 -1 pound per week. I've also stacked-on a heap of muscle. I'm not in starvation mode; you don't build muscle while you're starving.
The trainer to which I'm referring to (Peter) instructs a senior swim-ercise class...he works with the old-folks crowd. I met him about 5 months ago, he's about 45 and looked like a pear. Every week that guy looked slimmer & trimmer. With just moderate cardio and a reduction in his bread/beer, he dropped some 37 pounds in 1/3 the time it took me to lose the same amount. He is not muscular, not in the least....he's got a jello-build, okay...maybe pudding, but it's not firm or muscular.
I'm 5' 8" and my body-fat% is digital-caliper measured by a certified nutritionist (and author of the article Wrangell made reference to) at 11.8%...which would suggest I'm rather lean; yet I weigh 225 frickin' pounds. In the words of Bruce Willis, in the awesome movie The 5th Element..."I am a meat popsicle". Look it up