-by Stephan Guyenet

The controlled human studies once again suggest that sugar and fructose are not inherently fattening, but that refined sugar can cause body fat accumulation when it’s used to increase the palatability, reward value and energy density of food and beverages. However, excessive consumption of refined sugar can promote elements of the metabolic syndrome, and this is due specifically to its fructose content.

Conclusions:Here are the take-home points from this post:

1. Sugar, including fructose, is not inherently fattening relative to other calorie sources, and unrefined sugar is compatible with fat loss in the context of simple whole food diets.
2. Sugar can be fattening in certain contexts, specifically if it is added to foods and beverages to increase their palatability, reward value and energy density.
3.Sugar-sweetened beverages are probably one of the most fattening elements of the modern diet.
4.Fruit is not fattening, and it may actually be slimming.
5.In excess, refined sugar can cause body fat to redistribute from the subcutaneous depot (under the skin, where you want it) to the visceral depots and the liver (where you don’t want it). It can also cause insulin resistance in the liver and increase blood pressure, all components of the ‘metabolic syndrome’. This is caused specifically by the fructose portion of the sugar.

Here are the implications:
1. Avoiding sugar-sweetened foods, and particularly sugar-sweetened beverages (soda, punch, sweetened coffee, cocktails, maybe fruit juice as well?) can prevent and to some extent reverse fat gain and metabolic dysfunction.
2.I see no reason to believe that refined and unrefined sugars, used in the same context (e.g. muffins baked with white vs. brown sugar), would have different effects on body fatness. However, unrefined sugars may be less harmful to other aspects of health, because they contain other substances that may be protective. Mark Sisson discussed this idea in a recent post on honey (38).
3.Eating fruit does not contribute to fat gain in most people, but instead probably favors leanness. Fruit is a whole food with a low energy density and a moderate palatability and reward value.

This is just a snippet. Go to the Source: Whole Health Source: Is Sugar Fattening?