Yesterday I read a great article from Dr. Mercola called:

Finally Science Confirms the Secret Key to Weight Loss.

I want to expand on this article. Basically researchers in Boston compared A low–glycemic load (40% carbohydrate and 35% fat) vs low-fat (55% carbohydrate and 20% fat) diet. They found that reducing the glycemic load may be especially important to achieving weight loss among individuals with high insulin secretion. They also stated that regardless of insulin secretion, a low–glycemic load diet has beneficial effects on high-density lipoprotein cholesterol and triglyceride concentrations but not on low-density lipoprotein cholesterol concentration. You can check out this study by following the link:
http://jama.ama-assn.org/cgi/content/abstract/297/...

The researchers did state that the results of clinical trials involving diet in the treatment of obesity have been inconsistent, possibly due to inherent physiological differences among study participants, which makes sense considering our biochemical individuality or different diet needs.

But I believe the value of this research is in the importance of those overweight to be aware of their insulin levels (your GP can test it) and reducing them through a diet consisting of less sugar and processed carbohydrates empahasising lean meat, fibrous carbohydrates (above ground vegetables), low GI starches (brown rice, sweet potatoes), and good fats and oils (fish oils, coconut, olive).