50 grams of sugar more fattening than 50 grams of rice?

Apparently it makes no difference in body comp.
http://www.simplyshredded.com/the-science-of-nutrition-is-a-carb-a-carb.html

http://www.ncbi.nlm.nih.gov/pubmed/11093293
http://www.ncbi.nlm.nih.gov/pubmed/15277154

If you take a look at some of the references provided, namely some of the one's he bases most of his argument on, there are some big problems with the studies. Either poor science or poor reporting.

For example, in that first link to the Carmen study, look at the results:
"Body weight loss in the low-fat high simple carbohydrate and low-fat high complex carbohydrate groups was 0.9 kg (P < 0.05) and 1.8 kg (P < 0.001), while the control diet and seasonal control groups gained weight (0.8 and 0.1 kg, NS). Fat mass changed by -1.3kg (P< 0.01), -1.8kg (P< 0.001) and +0.6kg (NS) in the low-fat high simple carbohydrate, low-fat high complex carbohydrate and control diet groups, respectively. Changes in blood lipids did not differ significantly between the dietary treatment groups."

A great example of where statistics and p-values can be used to mislead people. Number one, we know next to nothing about the actual composition of these diets. They only cause us to think based on stereotypes of what a simple sugar and a complex sugar are, and cause us to make conclusions on assumptions. The sample was 300-some obese subjects, and we aren't told total caloric intake. Simply having varied these treatment's caloric intake could account for the change, especially when they are obese to begin with. The mean loss/gain in weight for the groups was less than two pounds for every group when we know the human body can vary in weight by that much throughout a given day. So the p-values, despite being statistically significant still do not make that valuable information, let alone the fact that we aren't even sure what was being measured or what it was being measured against (a null hypothesis of no difference between the diets or that there would be no weightloss at all). Its just not insightful in the least.

What did the typical american diet interventions look like? What did these control diets look like in comparison of fat intakes. What were the sources of fat? How was daily activity controlled for?

The fact is there are just too many things to take into account, and this is one of those studies that tries to lead you to an assumption that it isn't actually capable of leading you to. With weight loss, similar to hair loss, there are so many variables to can contribute, that completely controlling for them is nearly impossible. Take these ones with a grain of salt, especially when the person citing them in their simplyshredded article proclaims himself an academic.

Yeah there are many variables but still interesting

Also, one has to take into account the effect of digestion: digestion does not come for free energy-wise.
Digesting grains (and other complex carbs) will yield far less in net energy after digestion.
Also, by design, some of the starches will simply always be non-available, more so with glutenous grains, and more so with fiber.
On the other hand, fructose will yield more thermo-genesis than glucose.