Monday, December 10, 2007

Low-Carb, Too Much Stress on the Body? Say It Isn't So!

After seeing the article Low carb diets may stress body too much, studies find, on Carol Bardelli's blog, discussion about it on Active Low-Carber Forum, and receiving emails asking me about my thoughts on it, I decided perhaps it's time to add a post here about it.

The article includes one important paragraph that I'll focus on:

The ASU researchers Carol Johnston and Pamela Swan, along with collaborators Sherrie Tjonn and Andrea White, both registered dieticians, and Barry Sears, of the Inflammation Research Foundation and creator of the Zone diet, have published three papers during the last two years, appearing in Osteoporosis International, The American Journal of Clinical Nutrition and most recently in the Journal of the American Dietetic Association.

From the publications above, it's claimed that researchers have found:

1. With these studies, their research uncovered that the ketogenic diet may increase bone loss because of an increase in acid in the body and not enough intake of alkalizing minerals like potassium to neutralize this effect. In addition, a higher percentage of calcium was found in the urine of those on the KLC diet, leading the researchers to believe that the bones are “leaching” calcium.

This would be the finding from the unpublished data included in a Letter to the Editor published in Osteoporosis. It was from a cohort following a low-carb diet or non-ketogenic low-carb diet for two weeks.

Two weeks?

Haven't longer studies reached a different conclusion? The link I just provided is also in the journal Osteoporosis, but it's from a three month study and in it, the researchers concluded, "Although the patients on the low-carbohydrate diet did lose significantly more weight than the controls did, the diet did not increase bone turnover markers compared with controls at any time point. Further, there was no significant change in the bone turnover ratio compared with controls."

2. Another study by these researchers looked at the metabolic advantage of one diet over the other. They found that the reduction in fat loss and weight loss was about the same for both diets over a six-week trial. In addition, body mass index was significantly lower after six weeks in both diet groups. However, those following the KLC diet experienced a greater increase in LDL cholesterol than those following the NLC diet. HDL cholesterol did not seem to be impacted significantly.

This would be from a six week trial comparing the effect of a ketogenic low-carb diet and a non-ketogenic low-carb diet, where the researchers finding was as stated above.

Interesting little problem can be seen, however, when you go to the full-text of the paper - I'm very curious about what they fed (or recommended) those following the ketogenic diet - they managed to get 15g of fiber in them, yet failed to reach recommended intake for folate, vitamin E, iron, magnesium and potassium.

What were they feeding/recommending to these people?

Yes, this is a study I have serious questions about - because it is virtually impossible to miss folate if one is eating non-starchy vegetables as the majority source of carbohydrate, just as it is virtually impossible to miss vitamin E for the same reason. Add to this, failing to meet iron is next to impossible with the combination of meat and leafy greens when one is following a low-carb diet properly, and even magnesium and potassium should come in at levels at least above 80% of recommended intakes.

I even emailed Dr. Sears shortly after the paper was published, asking specifically, "I'm reading through your paper published in the AJCN this month and wondering what was on the menu for both groups? I see the macronutrient and micronutrient values, but am having some difficulty understanding what was provided for meals since some of the nutrient values are quite disparate (like the carbohydrate, cholesterol and polyunsaturated fats). Would it be possible to send me a day's menu of each diet so I can better understand the types of foods the subjects ate during the study?"

Oddly, I received no reply - usually Dr. Sears replies when I email him a question, but with this request for information, he did not. Of course, my request remains open for him or any of his researchers to email me and until such questions are answered about actual food consumed on both diets, the data remains suspect in my opinion since we don't know what was eaten to influence such a nutrient deficiency, which indeed may have influenced the outcomes seen!

3. They also noted that dieters on the NLC diet versus the KLC diet experienced more energy. Their most recent article published in October explains that the body needs carbohydrates for energy so if you are taking in an extremely low amount of carbohydrates and only receiving energy from protein, intense exercise is actually harming your body more than helping it. Without adequate amounts of carbohydrate stores, or glycogen, muscles rapidly fatigue during sustained exercise.

This is from a two-week trial. What's with this two week data offered up as proof these days?

Folks, this one is just a no-brainer. Dr. Steve Phinney has found, and published that time to adapt to a ketogenic diet is required, and once adapted endurance returns to pre-diet levels. That the cohort reported being more fatigued in two weeks is not surprising - in fact, it's expected. "Impaired physical performance is a common but not obligate result of a low carbohydrate diet. Lessons from traditional Inuit culture indicate that time for adaptation, optimized sodium and potassium nutriture, and constraint of protein to 15–25 % of daily energy expenditure allow unimpaired endurance performance despite nutritional ketosis."


  1. The term "stress" is often bandied about in an arbitrary fashion. We should restrict the meaning of "stress" to its technical meaning, which is activation of the hypothalamic-pituitary-adrenal (HPA) axis. Eating carbs raises insulin, which turn activates the HPA axis. The more insulin, the more stress. This point is routinely ignored. Instead we have situation seen here, where researchers are overly focused on the effect of micronutrients, completely missing the big picture.

  2. Anonymous4:05 PM

    Barry Sears has always been an Atkins basher and has seemed to me to be jealous of the success of low carb diets. I remember some pretty bitter comments when his diet lost out in that diet comparison trial.

  3. I have a lot of respect for Dr. Sears - and on the diet trial comments he made, I actually thought he was justified in making the comments he did and said so here:

    With the study I mentioned in this post regarding my asking for details on the menus of those participating - it is the only email I've ever sent that Dr. Sears did not reply.....I remain very curious about what the subjects ate for both diets because the nutrient intakes (micronutrients) don't seem to mesh with what one would consume on either protocol.....seeing what they ate might shed light on why the groups had the outcomes they did, and actually help us all better understand the micronutrient impacts on both types of diets.

  4. In the mass of papers I have collected, I have a copy of a report about a study done in 2005 at Connecticut University (Clinical Endocrinology and Metabolism 90: 26-31, 2005) showing that the calcium that is excreted by people eating more protein does not come from the bones. The percentage of calcium in the urine that came from bone actually went down. The extra calcium was the result of excess calcium being absorbed from the intestines.

    Two other studies, one done on children (American Journal of Clinical Nutrition 82: 1107-1114, 2005), and one on over a thousand elderly women (American Journal of Clinical Nutrition, Vol. 81, No.6, 1423-1428, June 2005.), showed that higher protein consumption resulted in greater bone density.

    Judy Barnes Baker
    "Carb Wars; Sugar is the New Fat"

  5. I'm willing to give the whole acid/base thing the benefit of the doubt and eat a little more spinach. If you look at the bone density of children, though, it's pretty clear hormones trump acid/base almost every time.
    Gotta wonder about the vitamin d status of the people in the study.
    If all we had to argue about was whether to eat 100 to 125 grams of carbs or to eat less than that, we'd all be skinny as Europeans. (Europeans in the sixties, anyway...)

  6. Thanks for blogging about this study.

  7. Anonymous6:00 AM

    Just a quick note, apologies if this has already been mentioned:

    Starchy carbs will generally increase the acid load on the body so I would find low carb/high carb irrelevant to acid/base load questions.

  8. Those of us who have been eating low carb for years find that we have more stamina, and that during those times that we eat higher levels of carbs, (vacations, holidays, etc.), we tend to have less energy, but after we get back to our low carb routine, the energy returns, the stamina returns. If this is stress on the body, I'll take it any day of the week.

    Someone needs to do a long-term study, using people who are dedicated to eating low carb, and keep track of their health markers over a period of months or years. I'm sure there are a lot of us willing to be guinea pigs to prove, once and for all, that a controlled carbohydrate approach is the healthiest way to eat.

  9. I am 56, been low carb for 5 years(about 40 grams a day) have lost 140 lbs. 2 months ago my bone density was checked and it is perfect. I can't believe these people who come out with this stuff. So intent on making the evidence say what they want it to, they can't see the forest for the trees.

  10. Carol is a bit miffed. I'm just surprised that she would post a study and not make any comment regarding it which implies that she fully agrees with the study. Maybe that is why she may have received some nasty comments or comments asking what her thoughts were on the study.
    I knew the study was full of inaccuracies and am glad it was discussed on your blog Regina. I do agree that you need more carbs for body-building but not all of us are into it.

  11. "Their most recent article published in October explains that the body needs carbohydrates for energy..."

    I thought that was the whole POINT of a ketogenic diet -- that the body became able to make its own energy using its fat storage as source, rather than incoming carbs.

    (On another topic sort of, I'm a little confused on why the fat is needed to be so high for sufficient energy, and how this jives with people always saying if you eat too much fat your body will use that for energy rather than your own fat defeating the whole purpose. If someday you could write something my little brain cells could understand about this, I'd appreciate it!)

  12. PJ - here's my best guess on the dietary fat question. If you have excess body-fat, it is due to insulin being to high, because the insulin "locks away" the fat so it isn't used for energy.

    Once you stop eating carbohydrates and your insulin drops, the fat begins to flow out of the fat cells. That you have this extra energy source available should serve to curb your appetite. The amount of fat you eat will likely be what's required to make up the difference. Just be sure to "listen to your body", and only eat when you're hungry (but definitely eat when you are hungry - no need for starvation!)

    That's been my experience, at least. For example, if I have a large meal (say, 16 oz. of steak with some sort of buttery sauce, veggies, and sugar-free ice cream), I typically am not hungry for the next meal or two. So I don't eat.

  13. Have you heard back from Dr Sears?

  14. Anonymous1:22 PM

    Actually you see more calcium in urine because calcium is used when metabolizing carbs, no carbs, no need for the extra calcium, so you body gets rid of it.

  15. There are certainly some risks when it comes to ketogenic/low carb type of nutrition, but it has effectively been used to treat various conditions, even epilepsy, so this should also be considered.