New Study: Low-Carb Vs. Low-Fat

This new study is making rounds today:
Effects Of Low-Carbohydrate And Low-Fat Diets: A Randomized Trial, Annals of Internal Medicine, 2 September 2014

It was a small study, 148 men and women. It pitted low-carb against “low-fat.” After 1 year:

Conclusion: The low-carbohydrate diet was more effective for weight loss and cardiovascular risk factor reduction than the low-fat diet.

The goal for the “low-fat” group was less than 30% of calories from fat. Does anyone know what amount of fat they actually ate? Or anything else about their actual diet? Since they consumed cholesterol, they were eating animal food.

30% of calories from fat is not “low-fat.”

In times past, and in many countries still today, 30% is considered high-fat:

Update 1: Dr. Katz weighed in: Diet Research, Stuck in the Stone Age.
Dr. Katz in not a proponent of vegan diets or low-fat diets per se. He advocates eating whole foods, rich in plant foods such as whole grains, vegetables, fruits, nuts, seeds, beans, and lentils, and if that ends up being low-fat, so be it. About this study, he said the “low-fat” group didn’t change their diet much (trimmed ~5% from baseline fat) but the low-carb group did (cut carbs by 75%). And:

And finally, the low-carb diet, since it was actually low-carb, obviously was much more restrictive than the low-fat diet, which wasn’t actually low-fat. That had the predictable result: those on the low-carb assignment took in many fewer calories (this information in summarized in Table 2 in the article). … And so, the results were a foregone conclusion. Over the span of a year, obese people who ate less, lost more weight. And those who lost more weight had more improvement in their cardiac risk measures- which were mostly a mess in the first place due to obesity.

He was quite critical in the end:

I am an advocate of research that is fair, unbiased, and relevant in the real world. As the head of a clinical research lab, and the author of textbooks on research methods- I am an advocate of sound answers to sensible questions. This is a defense of sense, and good science. Neither of which was on display in this study. As best I can tell, neither was fairness – nor even honesty. The researchers themselves called their interventions “low fat” and “low carbohydrate,” and must have known from the start they were cooking those definitions over very different fires.

[This study] is both prehistoric, and propaganda. It was a comparison of a quite restricted, lower-calorie, low-fiber diet; to a less restricted, higher calorie, equally low-fiber diet. The first worked better for weight loss. Ignored in the mix? Was the diet sustainable when the intervention ended? Could families join in? Would the diet reliably improve health and prevent disease across a lifespan?

Update 2: Stephan Guyenet (who will be debating Dr. McDougall this Saturday in, “Is The Paleo Diet Right For You?”) weighed in: Low-Carbohydrate Vs. Low-Fat Diets For Weight Loss: New Evidence.
He says there was a 20% drop-out rate in both groups, which is not small. He says both groups received a daily prepared replacement meal which likely upped adherence to their respective eating plans. And this:

Interestingly, there were no differences in fasting glucose or insulin between groups, and if anything there was a trend for both to be lower in the low-fat group.

Update 3: Dr. Barnard weighed in: Low-Carb Beats ‘Low-Fat?’ Take a Closer Look.
Barnard says the “low-fat” group wasn’t low-fat:

The study’s biggest downfall is its definition of a “low-fat” diet as one in which no more than 30 percent of calories consumed daily come from fat — with no more than seven percent of calories from saturated fat. What might such a diet look like?

Someone following this definition could consume a McDonald’s fruit-and-yogurt parfait with granola and a strawberry banana smoothie for breakfast, a grilled-chicken ranch BLT sandwich and a large Coke for lunch, and a double cheeseburger with a large Coke for dinner. In fact, one could consume nearly double the total amount of fat in all of these foods and still stay within what this study calls a “low-fat” diet.

Only in America could this way of eating be considered low-fat. This study’s authors allowed their research to be skewed by our ultra-high-fat culture in which diets full of fast food, meat, dairy, and processed junk are the norm.

Update 4: I have my answer about how much fat the low-fat group was eating … 27.5% at 3 months, 27.9% at 6 months, 29.8% at 12 months.


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