"It doesn't matter where your calories come from, as long as you're eating less..."While this may be true, it's important to note that in the study all subjects ate "heart healthy" diets based around whole grains, fruits, vegetables, nuts, healthy vegetable oils, and decent amounts of protein. Also, every one of the obese participants were encouraged to exercise at least 90 minutes a week. So they all ate a pretty healthy diet -- low in simple sugars and saturated fats -- and exercised.
When you take an obese person -- used to sitting on the couch and eating junk food -- and give them a low-sugar diet and regular exercise, that person is going to lose significant amounts of fat over 6 months (the period of the study) no matter what!
So yes, the "best" diet for weight loss is definitely one low in processed foods, high in "good" carbs and healthy fats, with plenty of protein included. Over time anyone will lose weight on that kind of diet, mainly because you're replacing bad calories with good calories... and you're almost definitely eating fewer calories with much more fiber.
But what about the best diet for fast fat loss?
In order to lose body fat as quickly as possible, you need to take a slightly different approach. First of all, you must avoid ALL simple sugars, even fruit juices. Second, you should avoid most starchy carbohydrates, even whole grains and white potatoes. These foods all contain lots of concentrated calories and the kinds of carbohydrates that can spike blood sugar levels and cause your body to pump out insulin, the "deadly combo" that stops fat loss in its tracks.
For fast weight loss, you should eat almost nothing but the following:
-- lean proteins (especially lean meats)
-- whole eggs and egg whites
-- vegetables and raw whole fruits
-- beans and legumes
-- nuts and seads
-- healthy, minimally-processed fats (e.g. virgin olive oil and coconut oil, natural peanut butter, etc.)
You should combine the above foods in healthy, balanced ratios for every meal and snack you eat. You should try to eat 5-6 small meals and snacks instead of 2-3 big meals. You should always focus on eating lean protein, high-fiber carbs, and good fats in order to control appetite and avoid food cravings. These things will all boost your metabolism and speed up the fat loss process.
That's it. You won't find a better diet for losing pounds of body fat quickly and in a healthy, safe manner!