Low Carb Crock Pot Chili

Low Carb, Low Fat, Low Value Argument

The intense popular fascination with low carb diets and speculation that they are metabolically superior to low fat diets has long been a little tired. Admittedly, low fat everything in the 1980s — with a little sugar thrown in to make up for lousy flavor — was probably not such a good idea. But a hamburger wrapped in a lettuce leaf? Was that serious?

Anyway, Kevin Hall and colleagues have done us a favor and settled a couple of questions about the metabolic differences between these diet plans. In a very carefully controlled experiment, he has demonstrated that in fact, a low fat diet causes more fat loss in the short term than a low carb diet. They did see a slightly, but clinically insignificantly, greater weight loss in the low carb group. Still, the bottom line is that speculation about a metabolic advantage of a low carb diet for fat loss doesn’t hold up to close scrutiny.  The study was just published in Cell Metabolism.

And here’s where we need to jump back to reality. The truth is that these comparisons — as useful as they are for understanding metabolic effects of these diets — may not matter. Because this study is so tightly controlled, the investigators say, “translation of our results to real-world weight-loss diets for treatment of obesity is limited.”

As a practical issue, what really matters is a healthy pattern of eating you can follow — and enjoy — for the rest of your life. So if you’re still quietly enjoying a low fat diet that you worked out for yourself in the 1980s, keep it up.

And tell that smarty pants who’s been bugging you about low carb diets to stuff it.

Click here to read more in the Washington Post. Click here to read the study and here to read a companion editorial.

Low Carb Crock Pot Chili, photograph © rpavich / flickr

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August 18, 2015

4 Responses to “Low Carb, Low Fat, Low Value Argument”

  1. August 18, 2015 at 8:35 am, Kevin Hall said:

    Hi Ted,

    Actually, the study showed that the reduced fat diet led to less weight loss but more fat loss compared to the reduced carb diet. Also, the point of the study was not to recommend one diet over another. Rather, we wanted to know whether selectively cutting carbs from the diet, and thereby reducing insulin secretion, offers a metabolic advantage for fat loss compared to an isocaloric diet with selectively reduced fat that did not affect insulin secretion. The main message here was that there was no such metabolic advantage if carb restriction and maybe a slight statistically significant, although clinically insignificant, disadvantage compared to fat restriction.

    Best wishes,


    • August 18, 2015 at 9:00 am, Ted said:

      Thanks Kevin, for taking time to clarify. You’ve also uncovered evidence that my thinking, now clarified, is not so sharp as yours at 1:30am.

  2. August 18, 2015 at 1:52 pm, Karl J. Kaiyala, Ph.D said:

    Ted – The Hall et al. study really is first rate research. I think it’s worth mentioning that the study design was profitably informed by superb mathematical modeling performed in recent years by Kevin and Juen Guo.

    As a related aside, an unfortunate feature of most of the contemporary discussion regarding the role of carbohydrate-induced insulin secretion in fat storage is a failure to acknowledge the very complex role of insulin in the overall regulation of energy balance. Insulin tends to be viewed solely in terms of its ability to promote cellular fuel uptake in peripheral tissues.

    In fact, a large body of evidence indicates that insulin secreted by the endocrine pancreas enters the brain and acts on key neuronal populations as a feedback signal to limit caloric intake. Insulin also promotes the synthesis by fat cells of leptin, a critical negative feedback regulator of fat storage.

    Dr. Stephan Guyenet has delineated the serious theoretical and empirical flaws of the carbohydrate-insulin model of obesity (search on: The Carbohydrate Hypothesis of Obesity: a Critical Examination).

    • August 18, 2015 at 4:38 pm, Ted said:

      Thanks, Karl, for the added insight.