Bodybuilders know a lot about diet, especially in the context of controlling the body fat percentage - mostly because in their case, the diet must work, or else they lose the competition. They can't rely on the latest fad on Oprah's that may or may not actually work. So the stuff they do tends to have a solid reality-based backing.
Any bodybuilder will tell you that low-fat diets are bullshit. Carbs are probably more aggressive fat-builders than fat per se, mostly because carbs are absorbed quickly, while fats are absorbed more slowly.
It's interesting to see the convergence from various sources. E.g., some diets recommended by weightlifters for "maintenance" (only to preserve a certain physique), and the diet recommended by Ray Kurzweil on health and longevity grounds, are similar in that the recommended daily intake of macronutrients is 33% carbs, 33% fat, and 33% protein as percentage of calories, or roughly 2:1:2 in weight.
As a comparison, that's slightly more protein that most people normally eat, a heck of a lot less carbs than the average intake, and a fairly average level of fat intake. I actually did this; reducing carbs was hard at first, but I got used to it after a while. It's amazing just how high you can raise the total caloric intake, if you keep the macronutrients at 33/33/33 relative ratios, without starting to gain fat. I was eating over 3200 cal / day, with 3 hours of lifting weights / week as my only exercise, and I was neither gaining nor losing fat (but I was gaining muscle).
In my mind, there's no doubt: By far the easiest way (in terms of effort spent, hours in the gym spent, etc.) to lose fat is to reduce the total calories by reducing the carbs intake (don't bother with tweaking the fat intake), and lift weights either 2 or 3 times a week, between 30 and 60 minutes each. 2 x 30 is the minimum that produces results, 3 x 60 is the maximum that allows you to keep it up a long time without burning out.
Don't eat carbs below 25% of your daily caloric intake, or you'll start to feel pretty weak. In other words, reduce carbs, but don't be a carbs nazi.
EDIT: This message was edited several times.