Low-carb diet trumps low-fat diet, yet again
Moonrise, Jackson Hole (click to enlarge) photo by Daniel Eades
A study published in the current edition of the New England Journal of Medicine demonstrates once again that the low-carbohydrate diet is better than the low-fat diet in bringing about both weight loss and an improvement in lipid profiles. This study, as published, is not without its flaws, which we will get to in a due course. What I find amazing – or maybe I don’t – has been the press reaction.
First came the television reports (here, here and here), all of which reported the study as the Atkins diet triumphing over the low-fat diet and the beloved Mediterranean diet. TV was made for sound bites and sensationalism, so this report fits right in. Although numerous studies have shown the same superiority of the low-carb diet, the TV media seems to treat these studies in one of two ways: it ignores them or it treats them as a man-bites-dog kind of story. The print media has had a little time to reflect on the situation and is reporting the study in a different way.
Two of the primary press sources that many newspapers rely on for press releases are HealthDay and Reuters. Both of these reported this study incorrectly. The headline of the Reuters report is:
Similar weight loss on 3 different, popular diets
HealthDay weighs in with
Diet Plans Produce Similar Results
And follows up with the subtitle
Study finds Mediterranean and low-carb diets work just as well as low-fat ones
If you ever harbored illusions that the print media never lies, these two reports should cure you. And if these aren’t enough to persuade you, take a look at this dog’s breakfast of a coverage by Tara Parker Pope of the New York Times.
You can read the full-text of the actual study yourself and come to your own conclusions. And you can wonder why HealthDay and Reuters decided to run the story the way they did. Most newspapers that subscribe to these services will tend to report the study the same way. In fact, most will print the story verbatim from whichever agency they get it from. And many readers will simply glance at these headlines and figure they know the contents of the story. Or the headline will set their expectations for the story and will give them the take-home lesson.
As you can read, the study shows that the subjects in the group following the low-carb diet had a statistically significantly greater weight loss and improvement in lipid profiles as compared to those subjects following the low-fat diet and the Mediterranean diet. A number of other health parameters changed for the better with all the diets, but did not reach statistical significance between the diets.
I have a few comments to make on this study, but I want to let everyone know up front to take everything I say with a grain of salt. When it comes to reading medical studies I am severely handicapped if I have to read them online. I like to make notes, underline, and otherwise write all over the hard copies of studies that I review. I can’t do this online and so always don’t feel that I’ve really read the thing thoroughly if I read it online only. And I’m still here in Jackson Hole, where I have no access to a printer.
Having covered myself with the above caveat, I have found a couple of problems with this study. First, it would have been nice to have known the caloric intake of the subjects at the beginning of the study. Table 2 lists the caloric change from baseline from the beginning of the study, but not the actual baseline caloric intake, which makes it impossible with the data presented to tell what the actual caloric intake of the three groups were at the various points of the study. Consequently, it’s impossible to tell if the weight-loss changes came about simply because those on the low-carb arm consumed fewer calories or if something else is a foot.
Second, I would liked to have seen the data points for all the subjects, which is pretty easy to represent in a couple of different ways. This would allow is to see if the changes came about in pretty much the same way across the group of subjects or if it came about because there was a large weight loss in a few subjects that skewed the averages. It’s always nice to see all the data.
Third, I haven’t a clue why the researchers who ran this study decided to encourage those on the low-carb arm to
choose vegetarian sources of fat and protein and to avoid trans fat.
Say what? The avoiding trans fat I can understand, but if it’s the Atkins diet (or Protein Power, for that matter) that’s being tested, why on earth would the subjects be counseled to go vegetarian for their fat and protein? It beggars belief. One of the results of this bizarre recommendation is that the anti-low-carb-diet crowd can disavow the results of this study by claiming that the diet isn’t really an Atkins-style diet. You don’t think they would do that? Think again. Read all about it in today’s New York Times. Why didn’t the researchers just give the subjects the instruction to restrict carbs and be done with it? Your guess is as good as mine.
Finally, I can’t understand why the instructions to the low-carb group were to increase carbs to 120 grams per day after the initial two month induction. We don’t know how many carbs the subjects in this study were actually consuming because the data shows carbohydrate intake only as the percent of total energy intake, but without showing what total energy intake is. If we assume that the subjects were eating about 120 grams per day, we know that they were right on the cusp of having any advantage from the low-carbohydrate diet other than the spontaneous caloric restriction it brings about. Our bodies need about 200 grams of glucose per day for all the tissues requiring sugar for proper function. Under conditions of zero carb intake, the body replaces about 70 grams of this glucose with ketone bodies, leaving about 130 grams that the liver must produce, which it does via the process called gluconeogenesis. Consuming zero carbs puts the body into the metabolic status that drives gluconeogenesis. If we are consuming 120 grams per day of carb, as the subjects in this study apparently were, then we are riding on the edge in terms of driving gluconeogenesis. We probably are making a little sugar to bridge the gap, but probably aren’t in the metabolic status most of the day that gives the low-carb diet its real advantage. It’s interesting to note that the data from this study show that only about 8 percent of those in the low-carb diet arm were spilling ketones in their urine, which leads me to believe that most were probably not gaining the full metabolic advantage that a low-carb diet offers.
Despite the instruction to increase carbs to 120 grams per day, I believe these subjects had a long-term benefit from the two months of rigid low-carb dieting (20 grams per day) with which they started the study. Why do I believe that? There is a terrific study in Nutrition & Metabolism showing that subjects with diabetes who underwent a strictly supervised low-carb diet for six months, and who lost weight, improved blood sugar control and lipid parameters, were still showing the positive effects of this intervention 44 months later. These impressive findings seem to indicate that there is some sort of rejuvenation that takes place in people after they have spent a period of time on an honest-to-God low-carb diet that carries over for several years. Maybe this is the phenomenon we’re seeing in the subjects in this NEJM study. The two months of rigid low-carb carries over for the rest of the study despite the subjects cranking their carbs up to non-low-carb levels.
It’s really too bad that the researchers didn’t check all the lab parameters and measure weight loss after the two month induction period. And it’s too bad they made the silly recommendation to go vegetarian low-carb. And it’s too bad they encouraged the subjects in the low-carb arm to increase their carbs to 120 grams per day. But despite all these missteps, the low-carb dieters were still triumphant over the other diets. It just goes to show what a powerful metabolic strategy restricting carbs is.
In Germany’s Tagesspiegel, they reported Atkins and Med as being equal to, “maybe even better than!” low-fat, with the reporter giving the edge to the Med diet.
http://www.tagesspiegel.de/zeitung/Sonntags;art7761,2575164
He states that low-fat and Med women were limited to 1500 calories, whereas the men got 1800. The Atkins people (and I say ‘Atkins’ because a different article said they were limited to 20g carbs/day) were not restricted in calories.
Did everyone read the same study?
Here’s a link to Fox News reporting on this. They interview a spokesperson from Health.com who says the study was a “suprise” since the low carb diet won. Then she offers the all too predictable warning against “evil saturated fats,” and says you should eat “good fats” if you go low carb. Still though…all-in-all I’m pleased to see this kind of exposure for the low carb lifestyle.
http://cosmos.bcst.yahoo.com/up/player/popup/index.php?cl=8932341
To LeenaS et al with regards to “vegetarian atkins”:
Regina Wilshire pretty much has it:
I received an email today from a friend who asked one of the researchers about the reference to plant-based (vegetable) fats and proteins. Dr. Shai assured him that the low carbohydrate group was not advised to consume a vegetarian low-carb diet, nor were they specifically restricted from eggs, cheese, red meat, poultry or fish. Due to dietary restriction (religious) the group would not, for instance have a cheeseburger or butter on top of their steak. Olive oil featured prominently. The participants did read the Atkins diet book. And the examples provided of the types of meals was “For example, a plate could include : fish or fried/not bread coated chicken/or red meet, broccoli and mushrooms coated with eggs, roasted eggplants, vegetable salad (peppers, cucumber, green leaves, notlettuce) with olive oil dressing.”
I read somewhere else that the emailer in question is Dr Eric Westman, but I cannot relocate the exchange right now. Suffice it to say that the Israeli low-carbers got lots of animal fat and protein. Only the question remains: Why does the study claim to have urges the low-carb group to eat vegetarian stuff?
Here is a more detailed account of the Westman/Shai correspondance:
Eric Westman:
In reponse to the queries about what was eaten on the “low-carb” arm of
the study published this week in NEJM, I asked Dr. Shai to clarify what
kind of foods were eaten, because the sentence in the methods section
(page 231), “participants were counseled to choose vegetarian sources of
fat and protein,” has been interpreted to mean that this was a
“vegetarian low-carb diet.”
—————————
“Hello Eric,
This is kind of funny that some could think of a “vegetarian low-carb”
diet. Is it a new suggested strategy? could be interesting idea but this
wasn’t the case here. Our low-carb diet was based on Atkins, the
participants read the book and the recipes were more or less comparable
to what you know in the states. Beef is the main red meat. What could be
different? People here would not mix in the same meal meat and butter, a
salad is considered a very rich one and not a lettuce based, and the
main dressing is olive oil. As for beverages, same industry that makes
money everywhere.
For example, a plate could include : fish or fried/not bread coated
chicken/or red meet, broccoli and mushrooms coated with eggs, roasted
eggplants, vegetable salad (peppers, cucumber, green leaves, not
lettuce) with olive oil dressing. I understand that some of the
low-fat people find it hard to believe that such a low-carb diet was
tremendously favorable within 2 years in a well designed study, but
these are the facts and the science of tomorrow, with the next long term
studies in the pipeline, may confirm or not these findings.
Best regards, Iris [Shai]”
This from http://www.lipidus.org/node/1742
Maybe someone with Westman access could verify this, so a lid could be put on the discussion?
I have Westman access and the response is verified.
Dear Dr. Eades;
Sorry for sending this through here, as I’m just not sure you received my previous email. I truly understand if you can’t respond to all messages, but I’m just trying to make sure you received it at all.
The question in reference was about translating your book.
Rabbi Hirsch Meisels
Jewish Friends With Diabetes International
http://www.FriendsWithDiabetes.org
I didn’t see it, but I asked my wife, who goes through all the emails we get, and she said she remembered seeing it. She (and we) are woefully behind in all our correspondence.
But it probably won’t be possible for you to do a translation because the book publisher owns all the rights to all languages. Protein Power is already translated into Hebrew and is sold in Israel. The others haven’t been. When an entity – typically a foreign publisher – wants to translate one of our books, that entity contacts our publisher and arranges to pay an advance to the publisher for the rights to translate and sell in that language. We don’t have the ability or the legal right to make those decisions; only our publisher does.
what’s the name of the book in Hebrew? do you have a link where I can buy it?
I can’t read the name of the book because it is in Hebrew, and I can’t read Hebrew. I assume it’s the Hebrew for Protein Power, but it’s in three words.
The book is published by:
Triwaks Enterprises / Matar Publishing House
P.O. Box 17467
Tel-Aviv 61774
Maybe you could contact these people to get more information.
Best–
MRE
I went on the Atkins diet 6 years ago and lost 200 pounds. I have remained on a low carb diet regimen and exercise program and have maintained my weight ever since. I feel so much better when I stay low carb. I have known that this diet worked. I find it funny that the “experts” are just realizing that it works. If you will recall, the Stillman Water diet of the early 70′s was also a low carb diet and many people lost a lot of weight on it. The biggest complaint that I have heard is that people will gain their weight back after going off the diet. Well, duh.
Duh, indeed!