It is not that simple, simply because you cannot calculate the amount or rate of absorption. Your intestinal bacteria acts and reacts to changing foodstuffs. For example if your eating a consistent diet of the same foods regularly, your intestinal bacteria will become more efficient at breaking down the food over time. If you suddenly switch foods, it can become less efficient. That could be the case in this study.
Counting calories isn't an exact science (yet), but it is simple and objectively effective for weight loss. Even if not exact, you really only need to be "close enough" with a good margin for error built in.
I get frustrated when people complicate weight loss when explaining methods to people who are interested in losing weight, rather than just boiling it down to the fundamentals (intake less calories/energy than you burn). All the competing fad methods are based around this fundamental with their own spin (and usually tie in a product that the user becomes dependent on to maintain weightless).
http://blogs.scientificamerican.com/brainwaves/the-food-figh...