These types of studies are so discouraging!
They make a person not even want to try to lose weight. It was hard for me to overlook those studies, or when a "well meaning friend" told me that only 2% of people who lose weight keep it off. At the other extreme is another "friend" who told me sternly that "there's no reason why you can't be one of those 2% who keep the weight off!" That was equally frightening, to be under that kind of pressure. And you should read the depressing statistics about gaining weight back for women over 40...my age group.
The key for me is to ignore these studies and just concentrate on consistently exercising (walking, going to the gym, bicycling). I try to exercise for at least an hour every weekday...yes, that's 5 days a week without fail (I take weekends off to save my sanity and let my muscles recover). It's the only thing that works for me. Hard to do at my age (48), but I have gone from 201 pounds to 175. No special diet, just cutting back on portions a bit.
To be truthful, I do worry if I will be able to keep this pace up. What if I am injured or become ill? If I can't exercise, I am not sure if I could keep up the long term weight loss. But, it's a risk I am willing to take, as I am enjoying the process and the benefits of exercise.
So, at least for me, exercise is the key.

Kathryn