Low Fat diets … will not rule the roost for long

August 3, 2010

Low fat diets poitless?

One more turning point in the demise of low fat diets came this week. The Annals of Internal Medicine released the results of a two-year study examining the comparative effectiveness of a low carbohydrate diet in direct comparison to a low fat diet. Unlike many other studies, this one was comparatively long-term (two years) and explicitly factored ‘in’ education and lifestyle changes (counseling and exercise).

My buddy Jimmy Moore on the Livin’ la Vida Low Carb blog has a great breakdown of the study (he really dug deep and included lots of references), so I won’t do an exhaustive recap here, but will include a few of the highlights:

  • The low carb diet included no calorie restriction.
  • The low fat diet prescribed a limit of 1,800 calories per day
  • Both diets resulted in comparable weight loss
  • The low carb group wound up with more favorable cardiac risk factors (higher HDL, lower triglycerides, lower VLDL). The study concludes

For my part, it’s another in what I expect to be many more data points on the path to the demise of the entire low fat premise. I’ve read a number of articles about this study and remain surprised to find that the non-calorie-restricted element of the low carb diet is not emphasized more (even among those who would be inclined to point this out). Maybe it’s so well understood that many don’t think it bears repeating, but I do. This study compared one ‘diet’ that essentially asks you to be HUNGRY basically ALL THE TIME to a diet that says ‘each as much as you want until you’re sated – then stop.’ It just boggles my mind that this distinction continues to receive so little emphasis. Which one of of those two options are you likely to continue doing over a lifetime? For my part, I don’t like being hungry if I have a choice. This is the main reason why I’m convinced low fat diets will begin to wane as we come out of this phase of dietary orthodoxy. Why starve if you can accomplish the same ends via other means.

One more thing, while I’m at it. It’s not so much about this particular study, but about the metrics used for diet studies all together. As I write this, my body fat is down to about 12%, I have a 32-inch waist. Solely based on BMI calculations, I’m bordering on obese. What’s the point? The point is weight, while relevant, is not the most relevant factor to be measured. The very most important factor is abdominal (omental) fat. Failing the ability to directly measure abdominal fat, tracking overall body fat has to be a better factor to track than weight. Why are there no studies that track *fat loss* between competing diet regimens. Is it really that hard?! Would you care if you cut you body fat percentage by a 1/4 but remained at the same weight? Seems so simple, I must be missing something.

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2 Responses to “Low Fat diets … will not rule the roost for long”

  1. qualia Says:

    while i agree with most of what you said, the 20g carbs a day of the low carb group certainly can also be seen as “a restriction” from a conventional stand point. both diets were restricted; the one moderately in calories (it’s still 1800kcal after all), and the other severely in carbs (at least for the first 12 weeks). to say the low-carb diet was not restricted is technically wrong. the described process of “increasing the carb intake after the 12 weeks to meet the target weight” (or so) further illustrates this.

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    • KMT Says:

      Thanks for your comment. Good point. Well said. Thanks for giving me the opportunity to clarify.

      Yes – significantly limiting carbohydrate intake is a restriction in comparison to today’s conventional diet. That said, my perspective on the long-term dietary approach is more closely aligned with that described in Westman, Volek and Phinney’s “New Atkins” book than the low-carb diet in the study. You’ll find that the ‘maintenance’ phase of that approach in terms of ‘gross’ carbs (i.e. not accounting for dietary fiber) is not that far away from the norm.

      To the question about ‘restriction’ any sensible lifelong dietary approach will severely restrict sugars of all types in comparison to today’s convention. It’s staggering how much of our total carbohydrate intake is in the form of sugars. While I’m a very vocal proponent of a low-carb/high-fat dietary approach, I’m convinced that just eliminating the sugars would take us so far down the road that the low-carb/low-fat issue would be very close to moot.

      Where it *does* matter, though is along the satiety dimension – and that’s where I differ with you. A low-carb/high-fat diet in no way ‘restricts’ satiety, while a calorie-restricted low-fat/high-carb diet most certainly does.

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