I used to think some people were "carb senstitive" but I'm not sure anymore. I think most of these people actually just don't need very much protein, they could eat more carbs if they cut their protein way back...
i was overweight/obese most of my childhood. tried the low fat thing in the 90's. switched to the low carb thing in the 2000's. this year i am eating less protein and more carbs and i am leaner for it. there may be some other things going on as well. i did add in some tabata type aerobics 3x a week. but am not doing the 2+ hours of aerobics i used to do during the week.