In 1987, Dr. Israel Ramirez, a researcher at the Monell Chemical Senses Institute, whose research led to the theory behind the Shangri-La Diet, questioned the prevailing assumption that sugar causes obesity in humans. Rat experiments did not support such a simple idea, he pointed out.
The most recent issue of the American Journal of Clinical Nutrition has a review article that agrees with Ramirez (but, alas, does not cite him). Now there is clinical evidence that Ramirez was right. From the abstract:
Numerous clinical studies have shown that sugar-containing liquids, when consumed in place of usual meals, can lead to a significant and sustained weight loss