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The official website of Drs. Michael and Mary Dan Eades, low carb pioneers and authors of Protein Power.

Do men lose more weight than women on low-carb diets?

Men and women dining

MD and I just got back from Low-Carb Denver 2020 where I made a presentation that will ultimately make its way to YouTube.  Preparing for the presentation occupied most of my time before the meeting–I’m a chronic slide-making procrastinator–so I abandoned blogging for  a bit.

Fortunately, the organizers put me on just about first on Friday morning, the first day of the conference, which put me under undo pressure, but ended up great for me.  Since I am such a procrastinator, I’m usually making slides right up to the moment I go on stage.  If my talk is the 2nd or 3rd day, I miss a lot of the conference, because I’m locked away in my hotel room cranking out slides.  This time, since I was almost the first presenter, I was forced to get my frigging slides finished early and was able to attend and enjoy the rest of the conference.

I didn’t know until almost the very last minute whether the conference was even going to happen or not.  In fact, I was texting the organizers just as I was boarding the flight to Denver.  As it ended up, about a third of the presenters did not attend due to their institutional travel bans.  Consequently, I missed hanging out with a lot of good friends who didn’t make it to Denver.

Over the next few weeks, I’ll post on some of the presentations I thought would be of interest and informative to readers of this blog.

Today I’ll post on a presentation by Dr. Lucia Aronica from Stanford about a subject I’ve had my own suspicions about for ages.  But had no data other than my own pondering.

Back in 2018 a study done at Stanford and published in JAMA showed that men and women lost equal amounts of weight on either  a healthy* low-carb or healthy low-fat diet.

Here’s the set up.

609 overweight men and women average age 40 were randomized into two groups.  305 followed a healthy* low-fat diet while the other 304 went on a healthy* low-carb diet. Both groups had extensive counseling, dietary instruction, and hand holding for the one year duration of the study. Along with weight loss, the study authors were looking to see if genotype or insulin secretion had any bearing on outcomes.

As the conclusion reports:

In this 12-month weight loss diet study, there was no significant difference in weight change between a healthy low-fat diet vs a healthy low-carbohydrate diet, and neither genotype pattern nor baseline insulin secretion was associated with the dietary effects on weight loss. In the context of these 2 common weight loss diet approaches, neither of the 2 hypothesized predisposing factors was helpful in identifying which diet was better for whom.

The New York Times positively chortled with glee as it appeared that the low-carb diet was held to a draw by the low-fat diet.  Since both the low-carb and low-fat diets were healthy,*i.e., they were whole food diets devoid of refined carbs and sugar, it appeared that the difference between the weight-loss potential of the two diets disappeared when whole foods were used.

“The key to weight loss is diet quality, not quantity, a new study finds” screamed the headline above the NY Times article. Those nasty low-carb diets work no better than the low-fat ones as long as the low-fatters avoid sugar and refined carbohydrates.

But not so fast.

That was before the team took a new look at the old data.

Normally, I’m suspicious when research teams start slicing and dicing the same published data in an effort to generate yet another paper. But in this case, I believe the extra work was valid.

Dr. Aronica reported on how the study team re-evaluated the data by comparing how men and women responded to the two diets.  Did they respond differently to the two diets, or the same?

Before she revealed the outcome, she made the point that there is a difference between sex and gender.

Sex is basically the hardware and it is binary.  Gender is the software and is much more fluid than sex, the hardware.  She started by making an interesting point.  She asked us to take a look around at the other members of the audience.  She said odds are that the women are better dressed than the men.  She was right.  She pointed out a number of other differences between men and women besides dress in terms of likes and dislikes.

These are all generalizations, of course, as some little girls play with trucks while some little boys play with dolls.  But in general it goes the other way. Same with tastes in food and a host of other things.  Her point is that since there are many obvious differences between the sexes and genders, maybe there are differences in response to drugs and even diets as a function of both gender and sex.

So, with that jumping off point, the researches re-evaulated the data in terms of sex and type of diet.  What they found was most interesting.

The average weight loss over a year for the groups (composed of both men and women) was an average of 11.7 pounds (5.3 kg) by those in the low-fat group and 13.2 pounds (6.0 kg) by those in the low-carb group.  (The weight loss was more in the low-carb group, but it wasn’t a statistically significant difference.) Thus the New York Times article linked above.

When the team looked at the study outcomes by sex instead of by groups containing both sexes, a difference became apparent.

Accounting for baseline differences in body weight, men following the low-carb diet lost the most weight, while men on the low-fat diet and women on both the low-fat and low-carb diets all lost about the same.  Below is a photo from the slide:

What Dr. Aronica is talking about in her title, i.e., The Sex Round is that when looked at strictly from the perspective of sex, this is the outcome.

But what about gender? How does behavior and likes and dislikes fit into the picture?

That’s where it gets interesting.

The dietary goal of the low-carb group was to keep net carbohydrate intake below 20 g/day.  The other group–the low fat arm–was instructed to eat no more than 20g of fat per day.  Members of both groups deviated from those fairly rigid dietary limits.

But who deviated the most?  And from which diet?

During the year over which the study took place, the researchers spent a lot of time analyzing the dietary adherence to the above goals and measured compliance.  They were able to calculate a deviation score, which is a measure of compliance to the diet. As Dr. Aronica said in her talk:

A positive score indicated a higher than average deviation from the diet (lower compliance), and a negative score indicates a lower than average deviation from the diet (higher compliance).

According to Dr. Aronica, whereas the simple weight loss measurement is a function of sex (men lost more than women), the deviation score was more a measure of gender. Compliance is more a result of likes and dislikes and personal preferences or societal molding.

Turns out that men were more compliant on low-carb diets than they were on low-fat diets.  And were more compliant on the low-carb diet than were women on either the low-carb or the low-fat diet.

Women were more compliant on the low-fat diet than they were on the low-carb diet.  Here is the slide showing the compliance scores. Remember the positive direction indicates lower compliance.

Compliance men vs women low-carb vs low-fat

It’s difficult to tell from the slide above, but the men were similarly compliant on both the low-fat and the low-carb diets.  It looks like there is a big difference, but it wasn’t statistically significant.  What the graphic tells us is that men lost significantly more weight and body fat on the low-carb diet than they did on the low-fat one, despite being similarly compliant on both diets.  For men, low-carb was the big winner.

Dr. Aronica pointed out that

the women lost similar amounts of weight and body fat on low-carb and on low-fat despite being significantly less compliant to low-carb than to low-fat.

Which, of course, tells us that those women would have doubtless lost much more on the low-carb diet had they been compliant, just like the men did.

Dr. Aronica points to gender differences in fear of fat as a reason for the lack of compliance to the low-carb diet.  She says that typically men don’t have a problem with steak and other fatty foods, whereas there is

an extensive body of research indicat[ing] that fear of fat is greater in women than in men.

If this is true or not, I don’t know.  I make no claims to have anything but limited knowledge of that research.

What I can say is that I doubt that female readers of this blog have a fear of fat. Or otherwise they probably wouldn’t be here. But these women were recruited for the study from the general population around Stanford and randomized into each of the diet groups. They didn’t self select.

So, if there is a generalized fear of fat among women, then it would be expected that those on the low-carb diet would be less compliant. Especially if coming from the Bay Area where every dish is served with a handful of sprouts.

In the final analysis, data from this study shows the superiority of the low-carb diet as compared to the low-fat diet for weight loss, assuming good compliance to either diet.  If you take a group of men and women with similar compliance, and if they all started with a baseline weight of 100 kg (220 lbs), Dr. Aronica points out that women

lost 7 kg (15.4 lbs) on low-fat and 9 kg (19.8 lbs) on low-carb , whereas the gentlemen lost 8kg (17.6 lbs) on low-fat and 10kg (22 lbs) on low-carb.

(The difference between the men and women when all are considered at the same baseline weight is that for any given weight men generally have a larger muscle mass than women.)

Similar wt loss for men & women with similar compliance

 

The take home message is that if women are as compliant as men on low-carb diets, that’s the best way for them to lose weight and body fat.


*The word healthy when applied to diet is one of those grammatical things that drives me berserk.  Healthy is a state of being.  You can be healthy;  I can be healthy; your dog can be healthy. But food isn’t healthy; it is healthful. Steak is healthful; junk food isn’t. So  JAMA should be calling these healthful low-carb diets and healthful low-fat diets.  Not healthy.  At least the New York Times put “healthy” in quotes as it applied to the diets, letting those in the know that the editors at The Grey Lady knew better.  I should have done the same, but I put an asterisk instead. I fear I’m fighting a losing battle on this one. I just couldn’t post it the way they wrote it without at least a mention.

 

 

 

 

 

 

 

29 Comments

  1. Lauren Romeo, MD on March 23, 2020 at 5:58 pm

    Great breakdown. I look forward to your youtube talk.

  2. cavenewt on March 23, 2020 at 6:05 pm

    “*The word healthy when applied to diet is one of those grammatical things that drives me berserk. Healthy is a state of being. You can be healthy; I can be healthy; your dog can be healthy. But food isn’t healthy; it is healthful. Steak is healthful; junk food isn’t. So JAMA should be calling these healthful low-carb diets and healthful low-fat diets.”

    I have a different quibble with using the word “healthy”, because it is such a loaded value-judgment word. Usually when you see that word in a newspaper article having to do with nutrition, they’re talking about low fat. In this case, at least the authors went to the trouble of describing what they meant by “healthy”, but given my current focus on the type of fat in one’s diet, my first thought is “What were they counseled about eating polyunsaturated fats?” Which could’ve been another confounding factor, especially since women would probably be more inclined to be *good* and eat more polyunsaturated fats than men would.

  3. JR on March 23, 2020 at 6:15 pm

    Dr. Eades
    The original Gardner study did not find big differencess inbetween the diets, and Dr. Gardner seemed a bit disappointed, while there did no appear to be a suitable diet for “insulin sensitive” vs. “insulin resistant” people.

    Nice that further analysis finds interesting differences. Of course the diets were diluted by gradually letting more and more restrictec items back in it.

    Prof. McLauhglin found also something very interesting; the fat cell size was markedly different, hi-carb group developed much bigger cells. Like the capacity is being met much faster with carbs… I just saw a summary of a presentation, maybe there is something published.

    JR

  4. Dr. Laura on March 23, 2020 at 6:28 pm

    I think it is true that women fear being fat more than men. It’s definitely true for my husband and me.
    II think an extra 3 pounds is too much. Contrast that to my husband, who thinks an extra 15-20 pounds is no big deal. Possibly because we (women) lose our shapes faster with extra weight (especially when it shows up in our waistlines) and our clothes are more form fitting. Not so for men, whose clothes will hide a multitude of sins.
    I think the other reason is because men don’t judge other men on their looks. For that matter, women don’t judge men on the extra weight they carry. We women are more forgiving of men, but not of each other (or of ourselves). I don’t think that’s a bad thing, either.

    • Mia on March 26, 2020 at 4:51 pm

      I don’t think this is quite the fat he’s talking about. Think dietary fat.

  5. David on March 23, 2020 at 7:04 pm

    The claim is made of a distinction between sex and gender however the results are between men and women. Attitudes towards food is not an indicator of some putative gender – sex difference (there is none) but more a result of years of being told “fat is bad”, as well as a serious lack of understanding of physiology. It’s a problem of mental programming.

  6. Gretchen on March 23, 2020 at 7:14 pm
    • Michael Eades on March 23, 2020 at 9:13 pm

      I agree, but I can’t give up without a little fight.

      • Molly on March 24, 2020 at 10:11 am

        As a middle aged woman I also care about how my diet will redlect on my skin as well as my body. And I have always had high teiglycerides and cholesterol eventhough im healthy weight. So that my gender sex age all fighting the question of which way do I go! For sure men are less likely to feel an extra 3 but for women my age it can be a huge problem because at my age visceral fat becomes harder to work off. I wonder if post menapause is more like being a dude and low carb is better cause I need more fat for my skin hair nerves. Right. Id love to add age to her study. Great information for a personal trainor. Awesome article. Looking forward to more.

      • IBikeNYC on March 24, 2020 at 3:01 pm

        Hear; hear!

  7. Richard Feinman on March 23, 2020 at 7:17 pm

    As Cavenewt points out “healthy,” like “evidence-based,” “precision” and others that don’t come to mind immediately, is a value judgement but this is, after all, nutritional research, where value judgements can be used as facts. And where “diet” is a biologic variable even though everybody in the study is doing something different and where you present the manipulated data before the raw data. (check out the error bars on the data). The outcome of a diet experiment is not an average. Nobody loses an average amount of weight. At least they recognize la diférence between some subjects. What you want to know is the each persons change in weight as a function of some independent variable like, you know, how much carbohydrate they actually ate.

    For example, in Gardner’s original A-Z study he compared different “diets” and showed different effect on weight loss. Since carbohydrate was the key question and fat change (TAG: triacylglycerol), I plotted carbohydrate versus TAG. (Similar to your suggestion in dealing with Krauss’s misleading data on CVD risk factors). The results are at https://bit.ly/33IwPI5 (Gardners original on the left, my figure on the right) where you can see that carbohydrate is the controlling variable.

    It is amusing, however, after years of telling us that low-carb will kill us, the lipophobes are exulting in coming in even. In boxing title fights, a draw means the champion keeps his title. I don’t remember the exact middleweight fight (Sugar Ray Leonard – Thomas Hearns ?) where there was a questionable decision of a draw. Muhammad Ali said about it that if you want to defeat the champion you really have to tear him apart. Of course, there is still the question as to how low-fat got the title.

  8. Janice on March 23, 2020 at 9:04 pm

    The software aspect of the brain and mental attitudes makes sense.The software aspect applies to so many things including culture as well.

    So speaking of software, I grew up in Asia. Fatty foods are delicious, there is no fear. Back in 1996 when I started LC, it was easy for me to enjoy the convenience and portability of a small stack of Fiber Rye Wasa (which for a time was <6 net carbs, IIRC) topped with Brie and Salami. It was a daily habit. It made a quick portable brunch with tea. For the second and last meal of the day, I ate sit down, home cooked, low-carb meals in the evening. Losing weight, losing migraines, gaining better sleep and feeling stronger happened so quickly.

    Fear of fat would have made my progress slower.

    Not a very nuanced review here, but my experiences with Asian way of eating counts as software here too. Far East Asians generally do not have hard coded breakfast foods. Any time of day is good for pckled veggies, left-over beef and cabbage stir-fry, low carb hot-pot with fatty meat,red braised trotters, and so on. My 'software' made my LC initiation so easy. I had no second thoughts or worries over eating fatty food. And yep, I am a woman, and was not affected by westernized perceptions and limitations.

    On the world "Healthy" as applied to foods and ways of eating… Oh boy, I do have that same reaction of wariness. Most always, upon examination, that label as applied, is an indication of outdated propaganda.

  9. Sandra on March 23, 2020 at 9:41 pm

    I look forward to you resuming your blog.

  10. Stuart on March 23, 2020 at 10:33 pm

    Were the groups balanced with equal numbers of men and women? If I’m reading the graphs above correctly, if we assume equal numbers in each category and average the low-fat (LF) and low-carb (LC) we get 9.5kg weightloss for men and 7.5kg for women. A difference of 2kg or 26% which is surely significant . So how do they get an average of 6kg for LC and 5.3 for LF? Looks like the LC group had a much higher proportion of women than the LF group. It would also be instructive if they analysed the data by gender and compliance.

    (OK, just realised those numbers are for 100kg individuals but I think the point is valid, the need to compare like with like rather than a generalised average)

    Also the figures for loss of lean mass look odd. Why would the men on the LC diet lose double the mass of those on the LF diet? I would expect those on the LC arm to be eating more protein and lose less muscle rather than more.

    • Michael Eades on March 24, 2020 at 12:07 am

      There were 263 males and 346 females enrolled in the study.

      As to your question about lean mass loss…

      Lean mass loss usually accompanies any substantial amount of weight loss simply because less muscle is required to support and motate about a lesser amount of body weight. I have in my files a study in which the researchers put the subjects participating in a weight loss study in vests they wore at all times except while sleeping. These vests contained pockets into which weights of various weights (sounds weird, but don’t know how else to state it) could be inserted. During the weight loss, any body weight lost would be compensated for by extra weight in the vest, so that the subject would carry around the same amount of weight all day as was his/her starting weight. At the end of the study, there was very little lean mass lost. I would link to this study, but, unfortunately, I can’t lay my hands on it. MD is giving me grief because of my GAP (great amorphous pile) method of filing. It’s an old study, so it is in the GAP of old studies. Since ~2000 I have been keeping all studies digitally (she calls this the GADP method), and I have a way of retrieving them.

  11. Mary Wilhelm on March 23, 2020 at 11:41 pm

    There have been numerous studies showing muscles in women take considerably longer to fatigue and while adhering to the 220-age women express while excercising at comparable levels to their male counterparts feel they are experiencing both less exertion and less latic acid burn then the men.
    As a cardiologist what are your thoughts. Is it possible that the formula needs to take these factors into consideration in addition to % of max heart rate?

    • Michael Eades on March 24, 2020 at 12:13 am

      First, I’m not a cardiologist.

      Second, I’m not sure it matters in a weight loss study. I think you’re talking about type I muscle fibers and IIa and IIb fibers. The Ia are the endurance fibers, ad the type II are the quick action fibers. They have also been called fast twitch and slow twitch fibers. The type I fibers are more resistant to fatigue, while the IIb are less resistant. But I don’t recall having read anything about which ones might be lost most during weight loss.

  12. Stuart on March 23, 2020 at 11:54 pm

    BTW when can we expect a new reading list? I expect you’ve already read Philip Kerr’s final novel. Dead from cancer at 61, what a tragedy. Given the prominent role that smoking plays in his Bernie Gunther novels I can’t help wondering whether Philip wasn’t a smoker himself.

    Anyway, if you need any reading material I’d like to recommend Martin Walker’s ” Bruno Chief of Police” series. With its combination of detective work and mouthwatering descriptions of French cuisine it’s right up your alley. Ex-soldier Bruno is Chief of Police (solo municipal policeman) in the village of St Denis in southwest France. He finds himself dealing with murder, drug smuggling, terrorism, Resistance history and political intrigue. Like most of these series, characters introduced in earlier novels reappear in the later ones so it’s best to read them in chronological order starting with the first one, titled Bruno Chief of Police (apparently republished as Death in the Dordogne). For more info Walker’s website is
    http://www.brunochiefofpolice.com/

    Any news on when PP 2.0 might be published?

    • Michael Eades on March 24, 2020 at 12:50 am

      I have the latest Bernie Gunther novel–Metropolis–on my Kindle, but I haven’t read it yet. I keep putting it off, because I don’t want the series to end. And I’ve been waiting for a trip or something where I can just relax and read it. Don’t know whether he smoked or not, but according to his wife, who, strangely enough, follows me on Twitter, it was fairly sudden. He went to the doctor, got a diagnosis of stage IV CA (renal, as I recall), and was gone all too soon.

      I have read one of the “Bruno Chief of Police” books, and enjoyed it. I need to read more of them.

      I’ll try to get a book recommendation post up soon. I’ve got a sh*t load of them I’ve read since the last time I posted.

      Work moving apace on PP 2.0. Don’t have a pub date yet, but don’t despair, it’s coming. I hope it will be worth the wait.

      • Cathy on March 24, 2020 at 6:38 am

        Dr. Eades, you will LOVE the Bruno chef de police novels. They are full of what he eats and he loves to cook at home. Duck fat is his preferred fat for cooking and he gardens. Very enjoyable plots as well.

        • Michael Eades on March 24, 2020 at 12:04 pm

          I’m looking forward to reading more of them.

  13. Kathy Newman on March 24, 2020 at 8:38 am

    The average weight loss was between 11 and 13 pounds FOR AN ENTIRE YEAR OF EFFORT?!?!?!?!?! A whopping 1 pound per month?!?!?!?! No wonder the compliance was not perfect. I’m amazed people didn’t leave the study in droves.

    My husband asked me to put him on a low-carb plan last September. My compliance was WAY better than his, as he would still have his English muffin at breakfast, his side of starch at dinner, and cookies here and there. I didn’t have any of those things. At the end of 2 months he was down 20 pounds. Me, a mere 2 pounds. Then came the holidays. We loosened the reins a bit between Thanksgiving and New Year’s, but I loosened them only slightly and he basically dropped them. On January 1, I had gained 8 pounds and he simply stopped losing; he didn’t gain a single pound. As of today, I’m still trying to lose those 8 pounds I gained and he’s down yet another 10 pounds (30 pounds total).

    It’s only anecdotal, but I’ve heard the same thing from women for years.

    • Michael Eades on March 24, 2020 at 12:16 pm

      No, the average weight loss was between 15.4 lbs and 22 lbs over the year. Which still doesn’t seem like a lot, but this is a study with 609 subjects. When you recruit people off the street to enter dietary studies, you’re going to get people who are really committed and others who aren’t. You are going to get people who normally eat a lot of carbs get randomized into the low-carb group; and you’ll get people who typically don’t eat so many carbs get randomized into the low-fat group. What you end up with is numbers all over the place. Those people who really stick to the diet for the whole year do well. Those who just play at sticking to it don’t do so well. In fact, some of those folks may actually gain weight. At the end of the study, the researchers must average them all together. So for each person who lost 40 lbs, there may be one who lost only 4 lbs, which averages out to 18 lbs, which, as you pointed out, doesn’t seem like a lot of loss for a year’s worth of effort. It would be helpful to see all the data in these papers (this one isn’t published yet) as that would let readers see the variation in weight loss among all the subjects, but few ever publish that way.

  14. Keith on March 24, 2020 at 7:38 pm

    My son is a high school senior and has 2 math theories he is working to publish. His mentor describes him as the most gifted math student he has taught in 25 year as a college professor. But because my son will not be published prior to the college acceptance dates and because he missed an English question on his SAT, he will be attending our state school instead of an Ivy League institution. My son is much like the LC diet- vastly superior to those in the know, yet lightly regarded in mainstream circles. PS- Dr. Eades, the realization that you have written a new blog post is akin to the I feeling of waking-up on Christmas morning as a child- presents are about to be received.

    • Michael Eades on March 24, 2020 at 8:05 pm

      Yep, your son is like low-carb diet, i.e., lightly regarded by the mainstream. But, like the low-carb diet, which is gaining more acceptance every day, maybe your son will be able to get into an Ive League school in a later year. Sometimes it’s easier to transfer in as a sophomore or later than to get in with all the incoming freshmen.

  15. Valerie on March 25, 2020 at 6:34 pm

    There are glaring mistakes in Dr. Aronica’s first slide. For instance, compare the two women bars. Women on low-carb lose less fat mass and less lean mass, but they lose more weight. The math doesn’t work.

    Then, the “results” about weight loss for a given level of compliance are just wild speculation.

    This is too sloppy for me to trust anything else in this presentation. Maybe when they get it peer-reviewed and published (and hopefully reviewers do a good job), we can actually learn something.

  16. Thomas on March 27, 2020 at 8:25 am

    It’s worth noting that they selected a lot of young people for the study, who are much more likely to be insulin sensitive. Of course insulin sensitivity is a precondition for losing weight on a low-fat-diet (https://www.ncbi.nlm.nih.gov/pubmed/22831182). So the weight loss stats might have been very different (favoring low carb) if they had chosen, say, 50somethings for the study. The study does consider insulin, but this may not tell the whole story: Someone who has elevated insulin levels but good glucose control (which is probably very common in the considered age group) may react differently to someone whose glucose control is already impaired by prediabetes.

    And of course it’s a dangerous oversimplification to draw the line only according to fat intake. The studies with a HF diet that is high in omega-6 show disastrous results. Participants eating a lot of “heart healthy” sunflower oil (after all they were instructed to eat “high quality” food, https://www.ncbi.nlm.nih.gov/pubmed/28027950) might have a very different outcome than people eating healthy fats. This may also impact the low carb vs. low fat battle.

    • Michael Eades on March 27, 2020 at 4:48 pm

      All valid points, which is why it’s so difficult to do a really good study.

  17. SF on March 28, 2020 at 8:58 am

    As a woman, this really has me thinking about my own compliance with low carb and low fat eating. I know for me, eating meat is not a pleasure, while my husband cannot fathom NOT eating meat with every meal. But I do seem to feel better when I eat fat and protein vs carbs but I have always had hormone balance challenges and the carb cravings will always knock me out of “compliance”. If if I feel better eating low carb, a hormone swing or stress will overrule that and I will want pasta or bread where my husband will crave a big steak.

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