I recently received an email from a nutrition researcher who works behind the The Ivy Wall. He offered to give me occasional insider information about how nutrition research is conducted, but on the condition that I not reveal his name. He suggested I refer to him in my posts as “Fat Throat.” (As Dave Barry would say, I am not making this up.) He also asked that I not reveal the organization that employs him and said to refer to it as The Committee to Re-Erect The Pyramid, a.k.a. CREEP. (He is making that up.)
Last week, I wrote about the two-year study that compared low-fat and low-carb diets. Low-carb won the comparison as far as raising HDL, but other than that, the results were the same — at least according to the researchers. I noticed right away that the Atkins dieters essentially went on a maintenance program within the first year, but it was Fat Throat who confirmed that the researchers included the drop-outs in their final numbers to even up the weight-loss score for the low-fat diet.
Fat Throat also believes the researchers included the drop-outs in their calculations to help even up the cardiovascular scores. As he told me, “Follow the triglycerides.” (Okay, he didn’t use those exact words, but the meaning is the same.)
Here’s what he’s talking about. At the beginning of the study, these were the average triglyceride levels:
Low Fat: 124
Low Carb: 113
Now look at the change in triglycerides over the course of the study:
|Diet Group||3 Mos.||6 Mos.||12 Mos.||24 Mos.|
Within three months, the low-carb group had reduced their triglycerides by a whopping 40 points. That result held up at six months. At the one-year mark, the low-carb group was backsliding but still had a much more impressive reduction in triglycerides. And then, wouldn’t you know it, by the time the study ended, the low-fat group actually had an edge — because the reduction in triglycerides for the low-carb group had dwindled from 40 points to just 12 points.
As Fat Throat explained during a follow-up phone call, it’s highly unlikely a group of people sticking to a low-carb diet would experience a 20-point rise in triglycerides in the last year of the study, and even less likely they’d end up with a smaller drop in triglycerides than low-fat dieters over the course of two years. I believe his words were something like, “It’s not biochemically plausible.”
In my own experience, triglycerides are remarkably stable on low-carb diet. I’m not on a zero-carb diet by any means, but I probably keep my carb intake below 60 grams on most days. Every time I’ve had a checkup in the past three years, my triglycerides were right around 70. The people in the Atkins group reached that level, then averaged nearly 30 points higher by the two-year mark.
So I’m guessing either they weren’t on much of a low-carb diet by the end of the study, or we’re seeing the results of creative calculations performed on the estimated end-points for the drop-outs. Perhaps a bit of both.
If we could just take a peek at the actual food intake for both groups of dieters, we could clear up this mystery. That would also address my suspicion that the low-carb dieters reached maintenance level within the first year. But as I noted in the previous post, the full text of the study (slipped to me by Fat Throat in a plain manilla email) doesn’t list any food-intake figures.
This weekend, I received another email from Fat Throat to explain why: There aren’t any food-intake figures. The researchers didn’t track or record anyone’s actual diet. Yes, you read that correctly. Their reasoning apparently goes like this: food journals are often inaccurate, so we won’t ask the study subjects to keep them. Instead, we’ll just counsel them regularly about the importance of sticking to their diets, then assume both groups stayed within their fat-and-calorie or carbohydrate limits … then estimate data for the drop-outs.
In a two-year, $4 million study with “weight loss” listed as the primary outcome, there’s no recorded information about food intake … and yet I’m supposed to believe this study actually tells us something?
I’m starting to wonder if this group of researchers — all with long histories of praising low-fat diets in their previous works — didn’t track the data for fat, calories and carbohydrates because they were afraid they wouldn’t like the results. Perhaps they didn’t want us to see that the low-carb dieters — with no restrictions on calories — would only regain weight after increasing their carb intake to, say, half of what the government recommends. (This was a government-funded study, by the way.)
Or perhaps they intended to test the results of dietary advice instead of actual diets. If so, those Low-Fat, Low-Calorie Diets Equally Effective For Weight Loss headlines are looking pretty shaky.
All I know is, something doesn’t pass the smell test here. Fat Throat probably has an opinion on that, but he didn’t say. Next time, I may offer to meet him in an underground garage so I can ask more questions.