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This would be the finding from the unpublished data included in a Letter to the Editor published in Osteoporosis.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.
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."