Possibly all of the above as these types of "studies" using a very loose definition of what constitutes low carb have been commonplace over the past 15 years of so. Started with Atkins and now seems to be continuing today. Of course, the term "low carb" is relative and if not rigorously applied as below 50 grams per day. Therefore, the study's design is disingenuous to say the least. Relative to those eating SAD means they can peg low carb at 44% and still be correct. Important to read between the lines, as you're doing, but most don't.