This started out as a comment on my last post, but got a bit lengthy so I decided to make it a full post. I also addressed some issues with this study in another post those only interested in this study might have missed based on the non-descript title. Let me start by saying that I did a fair amount of updating on my last post after reading the supplemental materials, and as a result I have some new criticisms of this article, and most of my original concerns remain. So we're all on the same page, here's the study, and here's the Supplemental PDF.
Many are treating the results of this study as if it were conducted in a metabolic ward. This is not true, it was a free-living study except for 3-day hospitalizations for analyses. Now it wasn't your usual free-living study in many ways: Participants were paid and had all food prepared for them for the duration of the study (added all up, a little over 7 months!). Monday through Friday they ate one meal a day at the facility. Daily diaries were filled out documenting any "cheats" or foods left uneaten. They received counseling if they had difficulty complying with the diet. It is unclear, but it seems they were weighed daily, at least during the various 4-week weight stablizing/stable legs. Body composition by DEXA was only assessed before and after the weight loss phase. TEE (by doubly labeled water method) was assessed over the last two weeks of the 4-week pre-weight loss and test maintenance diet legs, activity was assessed by accelerometer for 7 days (it is unclear which week, I'm guessing the 4th week) for each test maintenance diet. REE was measured by indirect calorimetry. Intake was ramped up during the first 4 days of the stabilizing phase and subjects were weighed daily and caloric intake adjusted accordingly. Here's an important little piece of information in this regard from the supplemental materials: "We allowed the duration of the run-in phase to vary among participants, to account for individual differences in the rate of weight loss." And: "The energy intake required for weight stabilization at the end of the run-in phase was established as the energy intake for the entire test phase, with no further adjustments regardless of any weight fluctuation with the test diets."
Read more »
