Low-Carb Diets and Metabolism

I’ve been seeing reasoned debate about the effect of long-term low-carb diets for a while now, but this last week, things kind of exploded into a yelling fest.

Within what I can only describe a mean-spirited and pointlessly rude blog post from Matt Stone, there’s one interesting nugget of possible truth:

“…remember that prolonged dieting (this one, low-fat, low-calorie, or a combination) tends to shut down thyroid function. This is usually not a problem with the thyroid gland (therefore blood tests are likely to be normal) but with the liver, which fails to convert T4 into the more active thyroid principle, T3. The diagnosis is made on clinical ground with the presence of fatigue, sluggishness, dry skin, coarse or falling hair, an elevation in cholesterol, or a low body temperature. I ask my patients to take four temperature readings daily before the three meals and near bedtime. If the average of all these temperatures, taken for at least three days, is below 97.8 degrees F (36.5 C), that is usually low enough to point to this form of thyroid problem; lower readings than that are even more convincing. It may be appropriate for those of you who fit these criteria to be prescribed thyroid by your doctor, and if so, a natural form of the hormone, which contains T3, is far superior to the most popular form of prescription thyroid, synthetic T4.”

-Robert C. Atkins

Google books says it comes from The Complete Dr. Atkins. Since I don’t own that, and I’ve never read it, that would explain why I’ve never seen this quote.

Jimmy Moore responded in the comment section of Matt’s site as well as on one of his blogs. Richard Nikoley of Free The Animal leapt to Jimmy’s defense. Matt has also previously said disparaging things about Richard.

My concern about all of this is that vital information might be missed. A lot of former low carbers or current paleo dieters *do* seem to have thyroid or metabolic issues of some kind.

Jenny, who runs diabetes update, talked about why low-carb stopped working for her. The whole piece is worth reading, but here’s the introduction:

The enthusiasm for the low carb diet as a weight loss diet arises in the first few weeks and months when most people experience dramatic weight loss.

What rarely gets mentioned–especially in the miracle weight loss books–is that very few low carb dieters ever get to their weight loss goal, especially those who start out with a lot of weight to lose.

I am enthusiastic about the power of carb restriction to lower blood sugar to normal or near normal levels. I am not as enthusiastic about low carbohydrate dieting as the solution to tough weight loss problems.

Because even the online low carb community tends to believe that people who stall out are “not doing the diet right” and respond to stall posts with that assumption, most people who do stall out long term leave the discussion boards, leaving only those who have succeeded to greet the newbies.

I’d like to point out that “not doing it right” is *exactly* what the purveyors of conventional wisdom spew at fat people trying to lose weight. If eating less and exercise is not working, then clearly, you aren’t doing it right. Or you’re lying about what you’re eating and your workout schedule. I think these amount to the same thing, but “you aren’t doing it right” is a lot nicer than “you’re a liar”.

I’ve seen many of the same complaints on BBSes like Low Carb Friends and Active Low-Carbers and even on Atkins Diet Bulletin Board. People will complain (almost exclusively women, though this may be a function of the boards themselves rather than an indication that all the people having the problem are women) that they can’t lose weight unless they cut calories to 1,400 or even lower, and generally, they do this by eating very low carb because they aren’t (as) hungry that way. This does not seem to get them anywhere either, and most low carb books I’ve read (and I’ve read a lot of them) indicate that counting calories is a bad idea. While they admit that it’s possible to eat too much, they recommend you don’t count calories, but because almost everyone tracks their carbs in something like Fitday, they always know what the calorie count is.

Atkins says that if you have a lot of weight to lose, it’s OK to stay on induction a long time. So, people stay on induction a long time because, in their minds, they have a lot of weight to lose. At some point, their weight loss becomes negligible. They either add a lot of cardio at this point, or get very strict about what they are eating. The Atkins book says that after induction, you should be adding carbs back at the rate of 5g per week until you don’t lose weight any more, then back off a little. There’s a “carb ladder” that indicates the order. The ADBB folks who have made goal by following the instructions in the book always push for this, but I think it scares people to think they will stop losing weight, gain weight or even go on a carb binge, so they don’t do it.

In Lyle McDonald’s The Ketogenic Diet he has a section on hypothyroid and euthyroid stress syndrome that contains this sentence: “The decrease in T3 due to hypothyroidism must be contrasted to the decrease seen during dieting or carbohydrate restriction.” Basically, that the decrease in T3 is a known issue with ketogenic diets (Atkins is a ketogenic diet).

Any diet of sufficient length and restriction will slow the metabolism. It seems to take longer on a low-carb diet than a straight-up low-calorie diet, and it’s possible that alternate day diets or calorie cycling might be an even better option, but I think what a lot of low-carbers (Atkins and lwo-carb Paleo Dieters alike) are experiencing is an evolutionary adaptation that makes complete sense once you see it from the right angle. I think that it handily explains the idea of the Atkins “One Golden Shot”.

In my next blog post, I’ll try to give the right angle.