As someone who spent most of my life as the chubby kid believing that I was never going to change, I'll throw in my 2 cents on this topic:
First of all, I've lifted for many years. I was relatively big, but never cut. Body fat probably hovered in the mid to high teens. Like most people, I believed that the issue was just a lack of cardio. So I'd do more cardio, lose a bit of fat, but then if I ever got off the routine it'd all come rushing back. It wasn't until the beginning of this year, after 13 years of lifting, that I realized it ALL comes down to diet. I'm not just talking about "eating clean," which I normally tried to do, I'm talking about being scientific about it and tracking your precise macro-nutrients daily.
So, starting at the beginning of this year, I began using the MyFitnessPal app on my phone daily. It told me I needed 1900 calories a day for my weight loss goals. I began the journey at 215 lbs. At that point, I would do at least 20 minutes of cardio 6 days per week, even on lifting days of course. And the weight started coming off quickly. All the while I kept gaining strength as well. Everything went along swimmingly until I got down to 195 or so. I was still making strength gains, but the fat loss stopped, so I figured I needed to retool things.
What I eventually came to realize is that (at least for me), finding foods that I could get the most quantity for the lowest number of calories was important, thus I eat a significant amount of cottage cheese and egg whites, as well as lots of veggies, good protein sources, etc etc. Also, the carb intake doesn't matter nearly so much as keeping your simple sugar intake as low as possible. The only way to accurately track all this is by being diligent with a website like My Fitness Pal.
Anyway, I switched things up, did more HIIT, and the weight slowly kept coming off. As you work your way towards the single digit bodyfat percentages though, you end up hitting the top of the bell curve. Your strength gains stop, your body is operating at full efficiency, and weight all of a sudden just wants to start dropping off. It's a double edged sword though b/c it also becomes easy to lose muscle. For me, that is the point it has got to now, so again I have to restructure things for strength gains.
Through this whole adventure I learned a few things. First, if you aren't losing weight, track your calories, and keep lowering them until you see the results you want. Don't worry about what your caloric intake "should" be; everyone is different. Also, sugar is the worst thing you can have in your diet -- keep that out of your diet, and you'll have a huge advantage. Further, tons of cardio isn't the answer. Your priorities should be (1) your diet, and (2) intense lifting. This in turn will kick up your metabolism to levels that you didn't believe were possible. As BMCJames pointed out in his awesome photo log (and I agree), you should think of cardio purely in terms of exercise for your lungs and heart. I now only do 10 minutes of intense cardio every other lifting day and like I said, I have to keep ramping up my calories to prevent excessive weight loss. On two non-lifting days, I have now switched to doing 90 minute hot yoga sessions, which is a new experience, but one that I would encourage other bodybuilders to try. It really emphasizes weak points and will make you drop weight like there is no tomorrow.
Anyway, as I said, that's just my 2 cents. These are the things I've picked up having dropped 35 pounds in the last 6 months and being into single digit body fat for the first time in my life, so hopefully it's worth something!
