I'm not disputing that the obese need both diet and exercise to reach a healthy weight (that's pretty easy to see, just by looking at the Harris Benedict equation), I'm just making you aware of evidence that exercise on it's own does work for weight loss.
As for whether 11lbs of fat loss is significant or not, I guess that's mainly a question of where you draw the line for "significant". If you want to label anything less than 20lbs in 6 months "not terribly significant", be my guest.
Also, jogging 4x/week (what the paper described as "high intensity") is not a "large exercise load".
On the other hand, it takes 15 minutes to lose 100 carbs on a treadmill, and about 3 seconds to get them back at McDonalds.
I lost about 15 pounds earlier this year and it was entirely by changing my diet (and by changing my diet I mainly just cut out beer and pizza on the weekends which were a staple of my friday & saturday nights, and switched in sushi for the nights when i didn't want to cook and ate microwave food, that's it)
Now I'm going to the gym for 4 weeks, and I feel great. I have put on a little bit of muscle but I just plain feel better. But I'm working my ass off in the gym and my weight hasn't gone down 0.1 lbf, while I burned off 15 by just changing my diet and never stepping foot in a gym.
It might be significant if we could just assume that's a linear progression and you'll keep losing that every six months, but that's not a conclusion you can make. The bar for proving exercise works as a weight loss method in the literature is low, because it can't get over any higher bar than maybe ten pounds with a fairly large exercise load.
("But you're just citing your own anecdotal evidence!" In this case, only as a tidbit to show how unimpressed by that study I am, not because I consider it proof. Proof I'm leaving to others who have done it better.)