Dr. McDougall’s latest news flash answers the question. You should read the whole article by Dr. McDougall, but here’s the central point: A healthy diet for humans should consist mostly of complex carbohydrates. Both saturated fats and simple carbohydrates can be unhealthy. Both should be reduced as much as possible or entirely eliminated from your diet.
As a reminder of how natural a carb=centered diet is, McDougall says:
“Starches have fueled the engines of human civilizations for at least the past 14,000 years. Carbohydrates (starches), such as rice in Asia, corn in Central America, potatoes in South America, and barley and wheat in Europe, have provided the bulk of the calories for almost all human diets.”
Now, go read the whole thing here: http://www.drmcdougall.com/misc/2010other/news/weil.htm