That “Low-Fat Beats Low-Carb” Study

      84 Comments on That “Low-Fat Beats Low-Carb” Study

I’d have to dig through my Outlook archives to say for sure (and I won’t), but this one may have set the new record for the number of Did you see this?! emails I received.

If you follow the health news (and if you haven’t been on a retreat in the wilderness or otherwise deprived of the internet for the past week), you already know a new study declared that low-fat beats low-carb for weight loss … once and for all, end of story, final word, move along folks, there’s nothing else to see. Let’s look at some media treatments of the news.

From a BBC article titled Low-fat diets ‘better than cutting carbs’ for weight loss:

Cutting fat from your diet leads to more fat loss than reducing carbohydrates, a US health study shows.

Scientists intensely analysed people on controlled diets by inspecting every morsel of food, minute of exercise and breath taken. Both diets, analysed by the National Institutes of Health, led to fat loss when calories were cut, but people lost more when they reduced fat intake.

From a Washington Post article titled Scientists (sort of) settle debate on low-carb vs. low-fat diets:

Seeking to settle the debate, scientists from the National Institutes of Health set up a very detailed and somewhat unusual experiment.

They checked 19 obese adults (who were roughly the same weight and had the same body-mass index) into an inpatient unit at the NIH clinical center, for two-week increments.

For the first five days of each visit, the volunteers were given a baseline diet of 2,740 calories that was 50 percent carbohydrate, 35 percent fat and 15 percent protein. This wasn’t very different from what they were eating before. But for the following six days, they were given either a low-fat diet or a low-carb diet, each having 30 percent fewer calories. Each participant was also asked to exercise one hour a day on the treadmill.

After analyzing everything from how much carbon dioxide and nitrogen they were releasing to their hormone and metabolite levels, the researchers concluded that the calorie-per-calorie, low-fat diets beat out low-carb diets.

My favorite headline was from the Los Angeles Times: For fat loss, low-fat diets beat low-carb diets handily, new research finds.

Low-fat won handily? Must’ve been real butt-whippin’ demonstrated in those results.

It is a central dogma of the low-carb lifestyle: that while avoiding carbohydrates will force the human body into fat-burning mode, any diet that fails to suppress insulin will trap body fat in place and thwart a dieter’s hope of shifting to a leaner, healthier body type.

But researchers from the National Institutes of Health have found that the hallowed creed of Atkins acolytes doesn’t hold up in the metabolic lab, where dieters can’t cheat and respiratory quotients don’t lie.

So it was the Atkins diet that got a butt-whippin’ by low-fat. I repeat: The Atkins Diet. I don’t know about you, but I would take that to mean the diet prescribed by Dr. Atkins.

And how long did the diets last? Let’s check the LA Times again:

As the 19 subjects recruited for the current study dieted their way through four weeks of low-carb and low-fat regimens, Hall and his colleagues conducted brain scans and other tests to glean how diets with differing nutrient compositions affected their mood, motivation and sense of satisfaction.

My goodness … they dieted their way through four weeks of low-carb and low-fat regimens, according to the LA Times. I take it that means the subjects were on diets lasting four weeks.  That ought to be long enough for real differences to emerge.

But wait a second … I seem to recall the Washington Post describing the diets a bit differently …

But for the following six days, they were given either a low-fat diet or a low-carb diet, each having 30 percent fewer calories.

Hmmm, we seem to have conflicting stories here.  Four weeks vs. six days on each diet.  Perhaps we should check the study itself – which I did. After reading it, I suspect we have a case of “let’s design a study to produce the results we want.” In fact, I can’t help but imagine the conversation:

“Okay, Jenkins, grab your laptop and step into my office. We need to design a good, solid, scientific study to settle this low-fat versus low-carb issue once and for all.”

“Excellent, sir. You mean in a metabolic ward and everything?”

“Exactly. Let’s start with the low-fat portion.”

“Well, sir, the usual definition of a low-fat diet is less than 30 percent of total calories, so I suppose we should—”

“Don’t be ridiculous, Jenkins. If we’re going low-fat, let’s really go low-fat!”

“Ahh, I see. Something like the very-low-fat diet Dr. Ornish pushes. Okay, 10 percent of total calories, then.”

“Damnit, Jenkins, you’re not listening! I said really low-fat! Let’s go down to, say, 7.7 percent of total calories from fat.”

“So a diet nobody would ever follow voluntarily in real life for any length of time, then?”

“Correct. Now, for the low-carb side of things …”

“That’s easy, sir. The Atkins books recommend starting at 30 grams of carbohydrate per day, so—”

“Good grief, man, we can’t put human beings on such an extreme diet!”

“But—”

“So we’ll go with 140 grams per day, including, say, 37 grams of sugar. That should be a fair comparison for our purposes.”

“But that’s twice as many carbohydrates per day as the Atkins diet recommends even in the maintenance stage, must less when starting a—”

“Well, it’s complicated, Jenkins, so let me explain it this way: shut up.”

Actually, the explanation isn’t particularly complicated. Here’s a quote from the full study:

Given the composition of the baseline diet, it was not possible to design an isocaloric very low-carbohydrate diet without also adding fat or protein. We decided against such an approach due to the difficulty in attributing any observed effects of the diet to the reduction in carbohydrate as opposed to the addition of fat or protein.

In other words, they didn’t want to add or remove protein from either diet, and they didn’t want to add fat to the low-carb diet or carbohydrates to the low-fat diet. They wanted to compare restricting carbs to restricting fat with no other changes, period.

Okay, fine. But in that case, the “low-carb” diet is nothing like the low-carb diet recommended by the Atkins diet books, or by any doctors who promote low-carb diets. So the accurate conclusion and/or headline should be something like Extreme low-fat diet produces more fat loss than a sort-of, kind-of, almost-low-carb diet … at least when the diets last six days.

Yup, six days. It was the Washington Post’s description of the duration that was accurate. The L.A. Times got it wrong. Based on those six days, the researchers then describe in their paper how computer models predict substantially more fat loss for the low-fat group if both diets lasted six months.

Uh-huh. I rank that up there with Al Gore claiming his computer models can accurately predict the climate in 2050 … even though those models didn’t accurately predict the previous 10 years. I’m a programmer, so trust me on this: computer-simulation models tell you what you tell them to tell you. The only way we’ll actually know how these diets perform over six months is to keep people on them for six months.

And we’d also want more than 19 people involved. I just wrote a post last week demonstrating how random chance alone can create “significant” differences in small study groups. Nineteen people, diets that lasted a whopping six days … I wouldn’t bet on those results being reproduced with large groups over a long time.

But about those results … the Los Angeles Times assured us the low-fat diet beat the (ahem) “low-carb” diet handily. So what were the big differences in outcomes?

Well, people on the low-fat diet lost (on average) 1.296 pounds of body fat. People on the (ahem) “low-carb” diet lost (again, on average) 1.166 pounds of body fat. The difference was therefore just a shade over one-tenth of one pound. If you don’t believe random chance can produce that trivial of a difference in a study group of 19 people put on diets lasting six days, I suggest you take a class in statistics.

But wait … did I say 19 people? Well, that’s not quite true. According to the paper, 19 people were enrolled in the study – 10 men and nine women. The study had a crossover design, meaning everyone goes on one diet, then goes back to normal eating for a couple of weeks, then goes on the other diet. They’re randomly assigned to do one diet or the other first.

But the results table shows n=19 for the (ahem) “low-carb” diet and n=17 for the low-fat diet. That means two of the subjects didn’t complete the low-fat diet. So I can’t help but wonder why the researchers didn’t simply toss the results for those two people from the study altogether. Why calculate their results on the (ahem) “low-carb” diet into the average if they didn’t finish the other diet? I thought the goal here was a head-to-head comparison of the same people on different diets.

I also can’t help but wonder why, given the small group, the researchers didn’t just show us the full results for everyone. In studies with hundreds of subjects, sure, you pretty much have to present group-average results to make sense of the numbers. But for the 17 people who completed both diets, heck, just show us everyone’s results and stick the averages at the bottom of the table.  If some individuals lost a lot more weight on low-fat vs. low-carb or vice versa, that would be worth knowing.  It would also be worth knowing if one or two outliers skewed the averages for the groups.

Well, apparently that did happen.  I found this in the paper:

The data were analyzed using a repeated-measures mixed model controlling for sex and order effects and are presented as least-squares mean ± SEM. The p values refer to the diet effects and were not corrected for multiple comparisons. One female subject had changes in DXA % body fat data that were not physiological and were clear outliers, so these data were excluded from the analyses.

Uh … okay.  I’d sure like to see those individual results, though.

All those complaints aside, there were some interesting results in the study tables (again, keeping in mind the small groups and short durations). During the six-day diets, triglycerides dropped by 17.5 points in the (ahem) “low-carb” group, and by 4.3 points in the low-fat group. For total cholesterol, the drop was 8.47 points in the (ahem) “low-carb” group and 19.1 points in the low-fat group. HDL dropped by 2.67 points in the (ahem) “low-carb” group and by 7.27 points in the low-fat group.

So if low triglycerides and high HDL are indicators of heart health (and if these results are actually meaningful), I’m sticking with a lower-carb diet … but one with more fat, thank you very much, because I want my HDL to go up, not down.

The results I found most interesting were for glucose and insulin. In the (ahem) “low-carb” group, glucose dropped by an average of 2.69 points … but in the low-fat group, glucose dropped by 7.1 points. So it’s clearly possible to reduce glucose levels with a very low-fat diet, despite the high carb intake, if calories are restricted enough.

This study has been hyped by the anti-Taubes brigades as a refutation of the insulin hypothesis, but the tables show very little difference in insulin levels. The (ahem) “low-carb” group showed a drop in fasting insulin of 2.76 points, while the low-fat group showed a drop of 2.04 points. Nonetheless, here’s how the researchers described the difference:

The experimental reduced-energy diets resulted in substantial differences in insulin secretion despite being isocaloric.

Hmmm … I’m thinking there’s a reason they chose the word “substantial” instead of “significant.” Let’s check the tables again …. Yup, the p value (RC versus RF) for the change in fasting insulin is .48. The threshold for “statistically significant” is .05 or below. So the difference here wasn’t even close to significant — in a study some people are waving around as proof that insulin levels aren’t a factor in the ability to lose body fat … perhaps because they read what the researchers wrote in their conclusions instead of checking the study tables.

And by the way, the p value (RC versus RF) for change in body fat was .78 — so unless I’m misinterpreting the meaning of p value (RC versus RF), we would interpret that as “statistically, the odds of this difference being due entirely to chance are 78 percent.”

Within the obvious limitations, the study does show that restricting calories can produce a drop in insulin even when the overall carb count stays the same. So it’s not as simple as carb intake = fasting insulin level. Total energy intake figures into it as well.

That being said, it would be very, very interesting to see what the differences in insulin levels (among other results) were if 1) the study ran much longer, 2) there were more than 17 people who completed both diets, and 3) the “low-carb” diet was actually low-carb and didn’t include 37 grams per day of sugar.

I believe the less-hype, more-substance reporting on the study was in an article that appeared in Forbes magazine online:

But a well-controlled new study finds that – at least in the lab – low-fat might be slightly better for weight loss over the long term. That does not mean that we should all revert to the low-fat insanity of the ’80s and ’90s. Rather, the more valuable take-home message might be that rejecting carbs may not be so necessary for long-term weight loss as many of us believe, and that a nutrient-balanced diet is probably the smarter strategy in the long term.

And frankly, whatever kind of diet is most doable for an individual is probably the one to be on. If it’s easier to stick to low-carb than low-fat, then by all means do it. But a balanced diet is still king.

Bingo. It’s certainly possible to lose weight on a high-carb, very-low-fat diet. It’s possible to lose weight on any diet if you restrict calories enough. I tried a Pritikin-style diet (10% of calories from fat) twice, and lost a bit of weight both times – and then I had to quit both times because I was miserable, hungry all the time, and eventually felt too lethargic and depressed to continue. Meals were an exercise in monkish discipline, choking down tasteless food and trying to convince myself I was fine with it.

Now I’m not miserable, not hungry all the time, and never depressed … which means when people hype a study like this as “proof” that a low-fat diet is better than an (ahem) “Atkins” diet, I can enjoy a hearty laugh.

Share

84 thoughts on “That “Low-Fat Beats Low-Carb” Study

        1. Tom Naughton Post author

          That’s about par for the course. I don’t think most of them even read the full text of studies.

          Reply
      1. Bob Niland

        re: I think the scientists got exactly the results they aimed to get.

        The lead investigator is known as the “high priest of CICO mathematics”. Now, being a CICO zealot isn’t necessarily a handicap, as long as one runs credible trials designed so that falsifying the hypothesis is a possible outcome. NUSI, for example, is skeptical of CICO, but is trying to be very careful to avoid bias in their trials, and let the tortilla chips fall where they may.

        This NIH trial may have been deliberately designed to produce a confounded result that Team CICO could spin any way they wanted to the pandering press.

        Or, being married to CICO, and government funding thereof, they may actually be incompetent to design trials that say anything meaningful about human metabolism.

        A reader on Diet Doctor may have found the smoking gun that provides some clarity in drawing a conclusion:
        http://www.dietdoctor.com/did-a-low-fat-diet-result-in-more-fat-loss/comment-page-1#comment-451032

        Reply
        1. Tom Naughton Post author

          That’s what made me suspicious of their intentions: the clear slaps at Taubes. Seems like they had an axe to grind.

          Reply
  1. johnnyv

    Yeah six whole days.
    Anyway what was wrong with say a 42.5% 42.5% 15% C/F/P Calorie split going to 12.5% 40% 15% and 40% 12.5% 15%? you end up with a fairly standard HCLF or LCHF diet out of it.
    After 30% Cal reduction via carbs C = 17.86% F = 60.71% P = 21.43%
    After 30% Cal reduction via fat C = 60.71% F = 17.86% P = 21.43%
    Keeps either diet from being a high protein diet.
    So at 70% of 2740 Cal
    C/F/P grams = approx 291/38/103 vs 86/129/103.
    38 grams of fat is a more realistic figure and 86 grams carbs while not induction levels is still very much a low carb diet.

    Reply
    1. Tom Naughton Post author

      Given some of the remarks they made, I suspect they set to poke Gary Taubes in the eye.

      I do understand their desire to keep protein constant and equal in both groups. Upping the protein seems to induce weight loss in many people, whether protein replaces carbs or fat. That’s why I’m not a fan of restricting protein to go into ketosis.

      Reply
      1. Tom Welsh

        If anyone is setting out to “poke Gary Taubes in the eye” they are very much mistaken. One of Gary’s huge strengths is that he has never been anything but a well-educated, curious, honest science journalist. That means he doesn’t have axes to grind like scientists (especially famous professors whose fame was built on a particular hypothesis), or politicians and bureaucrats who have inscribed a particular theory among the laws of the Medes and the Persians, and cannot ever tolerate having their chosen orthodoxy challenged.

        To the best of my knowledge, Gary has never staked his reputation on any particular set of beliefs. Rather, he established his reputation by reviewing the actual scientific research done in nutrition, comparing it with the conclusions stated by the scientists who did the research, and pointing out where the two differed.

        Reply
        1. Tom Naughton Post author

          My guess is that Gary himself disagrees with some of what he wrote in GCBC by this point. He strikes me as the type who changes his mind when he sees new evidence.

          Reply
        2. john

          “One of Gary’s huge strengths is that he has never been anything but a well-educated, curious, honest science journalist. That means he doesn’t have axes to grind like scientists (especially famous professors whose fame was built on a particular hypothesis), or politicians and bureaucrats who have inscribed a particular theory among the laws of the Medes and the Persians, and cannot ever tolerate having their chosen orthodoxy challenged.

          To the best of my knowledge, Gary has never staked his reputation on any particular set of beliefs.”

          Tom, I know you’re a comedian. I hope you find this post as funny as I do.

          Reply
  2. Guido Vogel

    I find it hard to believe that the researchers were neutral to low-carb.

    1) Study title: “Calorie for Calorie, Dietary Fat Restriction Results in More Body Fat Loss than Carbohydrate Restriction in People with Obesity”. Is is not a lie but leaves out a lot of context. Hall should be well aware of this and also the impact a title like this will have in the media. His own quotes in the media only enforces this (see my next point).
    2) Hall is quoted by BBC saying: “Dr Hall said there was no “metabolic” reason to chose a low-carb diet.” (http://www.bbc.com/news/health-33905745)

    So technically the study might be done quite well, but was the real question they were trying to answer?

    Reply
  3. Jesrad

    It’s very interesting (and, shall I say, SIGNIFICANT) that 2 of the 19 subjects couldn’t even do 6 days of their ultra-low-fat diet. That the researchers would still indulge in “long term” speculation off of that is ballsy…

    It’s also interesting that the metabolic rate decreased during the mid-carb-ish diet phase. I think Peter Dobromylskyj has the best explanation for that, here: http://high-fat-nutrition.blogspot.ca/2015/08/when-low-fat-wins.html

    Reply
  4. Troy Wynn

    a bogus study for sure. Where’s the validation? This I don’t understand. To take a hypothesis to press, it should be tested, then validated by other tests. One iteration is meaningless.

    Reply
  5. Vicente

    Hi Tom,
    did you have a look at figure 3E from the study?

    They didn’t measure a difference in fat loss between diets! They had to make up that difference by using models and equations, assuming that all the fat that wasn’t burned (according to their equations) was being stored as body fat. No fat in feces allowed, no fat used for other purposes than be burnt allowed, not even intramyocellular lipid changes allowed.

    They didn’t measure a difference: they made up one with their equations.

    By the way, this is my definition of a zealot:

    There may be some satisfaction in puncturing low-carb champions’ claims of metabolic superiority, Hall said.

    Reply
    1. Tom Naughton Post author

      Excellent review of the study.

      The sci-tech-today article is the same one that appeared in the LA Times.

      Reply
    2. gollum

      Why is this not a felony?

      Not measuring fat, that surprised even me (didn’t do any research further it was all so obvious from the press blurb)
      Not to mention that my body weight fluctuates by +-10 pounds depending on pipeline fill, tomatoes or meat, fluid intake etc.

      Reply
  6. Pat

    “The p values refer to the diet effects and were not corrected for multiple comparisons.”

    This is a no-no. A mixed-measures test (I am assuming some variant of an ANOVA) should be correcting for multiple comparisons, that is what they are designed to do. After all there are only two variables here, gender and diet. The blurb in Science Daily said they were all on one diet, then all on the other diet, which means diet order was not random.
    A graph showing each pair of points, with a line connecting each pair, will show trends very nicely – do the lines all go up? down? criss-cross like crazy?

    Re the study itself, not only are there the issues with diet composition, the actual run time was short – it takes time for the body to adjust enzyme output to match nutrient intake. Anyone who has shifted quickly from regular to low carb knows the first week is an adjustment period.

    Reply
  7. Sky King

    Great post! Thanks for doing all that analytical work for us. You’re a pretty sharp guy…. for a Hillbilly! ;-D

    Reply
  8. Galina L.

    I wonder where to conclusion “But a balanced diet is still king” came from? So far I see the opposite – the less balance a diet is, the better it works for a weight loss

    Reply
  9. William Norman

    I’ve been waiting on your analysis of this brief study. Excellent points regarding blood lipid profiles, insulin levels, and the amount of weight loss…

    It will be interesting to see if the results of the NuSI Energy Banalance Consortium gets as many headlines as this National Institutes of Health study… I predict that it WON’T if it doesn’t support any hypotheses of the anointed.

    Reply
    1. Tom Naughton Post author

      Perhaps, but the media seems less beholden to The Anointed these days when it comes to diet and health articles.

      Reply
  10. michael

    I never get the “nutrient-balanced diet” thing.

    Three macro nutrients: CHO, Fats, Proteins balanced between a 2000 kcal/diet yields: 666 kcals of each. Now, 33% of fat would never be considered as *balanced* by low-fatters, and 33% of carbs would never be considered as *balanced* by low-carbers, and 33% protein would never be considered *balanced* by pure paleo-ists, who are low-carbers and low-fatters at the same time!

    I say that “balanced” is a problematic word. It means anything to each different “expert” one can ask. Therefore, like Alexander with the Gordian knot, let us to cut up that stupid word and concept of our vocabulary and our thinking. When I’m asked, I recommend eating real food until satiety, and no more, whatever “real food” means to the person who asks.

    Balance is only possible if you are a gyroscope.

    I’m not a gyroscope, so screw balance.

    As for the caloric amount, I have doubts. Some people on a very high fat diet, low-carb, no junk, and 4000+ kcal do accumulate fat. Some people do the same, even more than that, and get leaner. Perlplexing. Also, I know of one woman on a low-calorie low-fat low-salt low-protein high-carb diet, who put on 4 pounds in 10 days. Perhaps she was eating lots of candy? Oh, if they only made fat-free candy!

    Reply
    1. Nate

      Thanks Michael, but you missed the correct definition of a balanced diet. A balanced diet is when you can pile your food on a plate, either round or square, and spin the full plate on your finger without spilling any food for a full minute. That definition was selected over the runner up definition. Go up and down the aisles of a large grocery store and take two items from each aisle.

      Reply
  11. PhilT

    I took the approach of reading the study, mainly the numbers, and ignoring the words and press releases. Interesting observations :-

    The men were insulin sensitive, the women were not.
    Two of the men didn’t do the reduced fat diet.
    Measured fat loss (DEXA / body weight) was not significant in women.
    Measured fat loss in men was significant, but the difference between diets was not.
    Glycogen depletion was significant in reduced carb, and observed in reduced fat.
    The reduced carb men had a lower calorie deficit than when on reduced fat.

    The biggest failing for me is the glycogen depletion bit – only half of the calorie reduction from eliminating 800 cals of carbs was met from burning extra fat.

    Reply
  12. Firebird

    “Well, it’s complicated, Jenkins, so let me explain it this way: shut up.”

    That was my laugh out loud moment!

    Meanwhile, in my N=1, I am week 4 into the Vince Gironda “Maximum Definition Diet” AKA the Steak and Eggs Diet. Intermittent fasting, 2 meals per day of steak and eggs cooked in butter. I eat 3-4 eggs per meal, 8-12 oz. steak, ground beef or hamburger per meal. I do eat a pickle or two or a forkful of sauerkraut for digestion.

    Every 5th day I have ONE carbohydrate meal. Some people go off the rails and take this to mean a pig out/cheat day. Gironda didn’t see it that way…he suggested a large salad, potato, fruit and even a plate of pasta…then go back to the diet. That is what I do…a bit of fruit, potato, rice, etc. I don’t look forward to this. I’m not big on carbs. What I actually crave is something different to eat. Having a bowl of rice is actually disappointing. So is the fruit.

    As of last Wednesday I am down 12 lbs.

    I don’t really have a BW goal. My goal is more BF%. I am around the 13-14% area at the moment. At a height of 5’7″ the 195 lbs. I was carrying just didn’t feel right. My comfort zone is 165-175 lbs.

    Reply
  13. Nate

    Wow, how naive am I? I have been saying that the NIH should step up and establish standard definitions for low carb, very low carb, very low fat, etc to help the conversation of nutrition be less confusing. Well, it appears that not only do they not want to help scientist have a more precise discussion, they want to add their own confusion.

    Another sad point is that you felt like you needed to say trust me that computer programers will determine the outcome by simply doing their job. The only thing I learned from my one and only course on Fortran was garbage in, garbage out. (And in 1969, that meant that faulty programming cards were literally garbage.) You mentioned Al Gore, but to me Cordain is in the same boat. I stopped reading his book after he said trust me I wrote a program to analysis the data so I’m right. A computer is just a tool like a hammer. Whatever you aim it at, you can mend it or break it.

    Reply
    1. Tom Naughton Post author

      You were expecting government to step in as the arbiter of truth? I hope you learned your lesson.

      Software programs are excellent for analyzing data already gathered. They’re not so excellent for making predictions of what the future data will be.

      Reply
  14. Michael Cohen

    This reminds me of a “Proposal” for a science project my son and I submitted for his middle school science class. It was called “The Effect of Hydrogen Hydroxide on Highly Exothermic Oxidation Reactions” We were going to “prove” that Hydrogen Hydroxide (water) had little or no effect on “Highly Exothermic Oxidation Reactions” (fire). We would simply make a huge wood fire (10 kilos) and observe the results in repeated trials when measured amounts of water from 1 to 10 ml were added to the fire . We set out to “prove” that in the experimental parameters, water had no effect on fire.

    Reply
  15. Vicente

    Guyenet (yeah, I know, I am sorry for linking to his blog) says that what the study supposedly showed was a transient effect due to the short duration of the study. While glucogen stores were being depleted in the lower-carb diet, there was a reduced rate of fat oxidation.

    Quoted from Guyenet:

    Together, this suggests that glycogen depletion in the first few days of the low-carbohydrate diet is the primary reason it caused less fat loss over the 6-day period. Without glycogen depletion, fat loss would have been more similar between diets, although Hall’s model predicts that the low-fat diet would still have maintained an edge

    But the authors didn’t say “we found no difference”. They said “fat restriction is better than carb restriction for weight loss”. This has a name: deception.

    Reply
    1. Bret

      Insufficient experiment duration notwithstanding, Stephan brought up an interesting point, that the results of this study cast serious doubt on the portion of the insulin hypothesis that implies carb restriction is somehow or another required for weight loss.

      The Jaminets made an intriguing point of their own in the PHD book, which is that a healthy body makes use of all three macronutrients each day…therefore, if someone is carrying extra body fat, it makes sense to reduce dietary fat intake, because this macronutrient is available from one’s own adipose tissue. This of course comes with the caveat that intake of the other macronutrients should be kept at reasonable quantities.

      Reply
      1. Tom Naughton Post author

        You can lose weight on any diet if you restrict calories enough. The point is to find the diet that allows you to consume less than you burn without feeling hungry all the time … because going hungry is the recipe for failure.

        Reply
        1. Firebird

          That’s what Dr. Greg Ellis said. You could eat 1,000 calories of nothing but chocolate cake all day but it is not recommended and the kind of weight you lose may not necessarily be fat.

          Reply
        2. Bret

          I suspect there’s a ton of variability throughout the world based on that criterion. And who knows whether food preference is an innate trait or a learned behavior.

          That’s one reason this low carb vs low fat business is silly to begin with.

          Reply
      2. Thomas E.

        If I may, you forgot to add, over a 6 day period is questions the role of requiring less insulin to lose fat.

        And someone carrying extra fat, well it depends where that extra fat is. If it is a triglyceride form in a fat cell, it requires work to get it out, and that work requires the help of hormones. If the diet prevent in that particular individual prevents the hormones from achieving that end, the triglycerides will stay safe and toasty in the fat cell.

        That is the point missing from your point. The body is a complex system.

        But again, back to the 6 day, the body is no way near homeostasis with the new diet. Long term effects can not be measured. Certainly over a short term, 6 days, the body is going to react differently than over a much longer term, also called life.

        This study that, at best, points to longer term studies, basically, how does the body respond long term. Let’s take these 19 people and keep them in those diets with a bit more than 2 hrs of exercise per week, not much more, and change the way they eat for 6 months and perform biometric measures at the beginning and end.

        So yeah, the body may have been able to cope with 6 days of LF (well except for the 2 that dropped out). But how about 6 months.

        Reply
          1. Walter Bushell

            Butt, as Denise Minger says, 10% and below is where the low fat diets work. It’s Ornish[1] et al.. Better to aim for under 8%, and by dog, that needs many supplements and constant doctor overview. For example where do the fat soluble vitamins come from?

            [1] “If it tastes good spit it out.”

            Reply
      3. Elenor

        “The Jaminets made an intriguing point of their own in the PHD book, which is that a healthy body makes use of all three macronutrients each day…therefore, if someone is carrying extra body fat, it makes sense to reduce dietary fat intake, because this macronutrient is available from one’s own adipose tissue.”

        Haven’t read their book, but I’d suggest that this “point” only works if one’s body allows the release-for-use of the fat in the fat cells! If (as for many women) you’re insulin resistant AND have high insulin, you’re not going to be burning any of your own fat! (Alas alas!)

        Reply
        1. Tom Naughton Post author

          Phinney and Volek actually make the same point in their books on ketogenic diets. If you’re aiming for 80% of calories from fatty acids but want to lose body fat, some of that 80% should come from apidose tissue, not from the diet. That does, of course, assume the fatty acids in adipose tissue are available.

          Reply
        2. Bret

          What’s the point, Elenor (or should I say “point”)? Sounds like someone fitting that description needs to regain their sensitivity to insulin…not hide from carbs and make their insulin resistance worse. There are abundant references in the scientific literature documenting that extreme carb avoidance promotes insulin resistance.

          Carb phobia, so far as I can tell, is based on people’s conflation of whole carbs with refined carbs. They foolishly avoid all of them, and then they double down on this strategy when they see bad insulin numbers. Reincorporating regular whole food carbs, fiber and all, would likely do wonders for most of them.

          Reply
  16. Galina L.

    My husband challenged me to take a nutrition course on-line last spring, and I did. The course started with the description of types of nutritional studies. It was a good start because it explained a lot about a nutrition being a very soft sort of science. A definite scientific proof in a nutrition is hard to get.

    Reply
  17. Steve and Lori

    Thanks Tom for taking the time to dive into this and clear it up ( We knew you could!)

    Now we have a reference for this study to refer people too when they continue to try to tell us the low-carb lifestyle has been bunked.

    Reply
    1. Tom Naughton Post author

      Given that the difference in fat loss was barely perceptible and the triglyceride and HDL numbers were better on the lowish-carb diet, this study didn’t debunk anything.

      Reply
    1. Susan

      Took a look at that video. Didn’t get much out of it aside from the fact that I’m REALLY REALLY tired of videos of overweight headless torsos walking down the street. SO tired!

      Reply
  18. Richard David Feinman

    I haven’t read everything written about this study but nobody seems to notice that we don’t know the results. The results are reported as average differences with SEM (standard error of the mean) a measure of the variability. That does not tell us how many subjects conformed to the average, that is, some of the people in the study might have done better on low-carb than low fat. This could be important because, without going into the details, SEM always makes your data better than it is. The more useful measure is the standard deviation which you can calculate by multiplying by the square root of n, which is slightly more than 4 in this case. This means that there were overlapping values between the two diets. Before we criticize the study we should recognize that we don’t actuallly know how it turned out.

    Reply
    1. Michael

      Thank you! That was a great comment.

      Do you reckon the report incomplete because of incompetence or because of another reason?

      Reply
  19. Éric St-Pierre

    Did you notice that the main investigator of this study, Kevin D Hall, is also the main investigator of the NUSI’s study (Energy balance consortium)…
    nusi.org/science-in-progress/energy-balance-consortium/

    This worry me a little…

    Reply
    1. Tom Naughton Post author

      That’s a good thing, actually. Taubes and Attia specifically decided to include people with opposing views.

      Reply
      1. Bob Niland

        re: … Kevin D Hall, is also the main investigator of the NUSI’s study …

        Having a skeptic on board is one thing. Having a zealot* on board is another, particularly one who has demonstrated either massive incompetence, or more perhaps in this case, advanced sabotage skills.

        I wonder if NUSI ever asked him: Are you willing to be mistaken?
        _______
        * Zealot: one for whom the dogma principles are more important than actual outcomes.

        Reply
  20. Vicente

    Hi Tom,
    exclusion criteria for this study (see) included “metabolic diseases”, like diabetes.

    Insulin resistant people may react better to carb reduction and low-glycemic diets (study,study). Insulin sensitive people may get better results with HF diets (results related to weight loss).

    Is it wrong to join the dots?

    For sure we can say this study doesn’t apply to people with metabolic diseases, because they weren’t admitted as participants (Why not?)

    Reply
      1. Vicente

        I accept that answer with cancer or thyroid disease, but I can’t see a reason for excluding diabetes, insulin resistance or fatty liver, if we are talking about obese people looking for a diet useful for weight loss.

        Reply
  21. Aditya

    Tom, thanks a ton for analyzing the study in detail. Given the actual ‘results’ and the published conclusion, the researchers were either entirely dumb or willfully ignorant, my money is on the later.

    Reply
  22. Paul B.

    What about my favorite macronutrient? ALCOHOL!

    “Balanced” is one of those words that, in this context, is so broad that it has no meaning (briefly discussed in a topic above).

    If researchers truly meant to even out all nutrients, then you’d have to split from not three, but rather four macronutrients (there may be more, but I was always taught that there are four), and then “balance” all of the micronutrients… whatever that means.

    Reply
  23. Butler T. Reynolds

    Thanks for clearing that up, Tom. When I saw the headlines the other day, I knew you’d clear it up for me!

    “But a balanced diet is still king.”

    For those wondering what someone means by a “balanced” diet, I’ve finally figured it out. Those who recommend a balanced diet are the same people who recommend “everything in moderation”.

    My observation is that people who say “balanced” and “moderation” are the types of people who have never had a problem with their weight. (Either that or they just don’t notice that spare tire around their middles.) Since they’ve never had to pay attention to what they eat, then obviously they must be eating a balanced diet with everything in moderation, right?

    While annoying, the balanced diet folks don’t mean any harm. After all, they have no clue in the same way I have no clue what it is like to be an alcoholic. I drink from time to time, but I can take it or leave it.

    Could you imagine the stares I’d get if I walked in to an AA meeting and said, “Look guys, the secret is moderation. There’s nothing wrong with a drink once in a while. Just don’t overdo it!”

    Reply
    1. Vicente

      Hi Butler,
      I just would add that addiction to processed foods is not necessarily present in every overweight/obese people.

      A diet rich in processed food (sugar, grains, vegetable oils) could make you gain weight without you developing an addiction problem with those foods.

      The cause of obesity is not over-eating, it is bad-eating, wether you develop an addiction or not.

      A related study:

      “The current study provides preliminary evidence that not all foods are equally implicated in addictive-like eating behavior, and highly processed foods, which may share characteristics with drugs of abuse (e.g. high dose, rapid rate of absorption) appear to be particularly associated with “food addiction.”

      (From “Which Foods May Be Addictive? The Roles of Processing, Fat Content, and Glycemic Load“)

      Reply
  24. Joe

    How many times do these studies have to come out? As soon as I heard about this diet my first thought was, “bet it wasn’t really a low carb diet”. Nutrition science is so pathetic. For the last 10 years the most well designed studies have consistently seen better weight loss and health outcomes on LCHF. I can’t wait until NUSI releases their results. Their studies are the most rigorous I have seen.

    Reply
  25. Joe

    I would love to see the reaction in the vegan world if low carb beat a “vegan” diet that only consisted of 15% calories from animal products.

    Reply
  26. Brigitte

    I would like it to be standard practice to include a photograph of each and every “meal” given to study participants. I think the general public can tell very quickly by seeing a photograph whether the food shown is enough to eat at each meal or not. Most folks can starve themselves for a time but not for the rest of their lives as most very low fat diets would require. The beauty of low carb is there is enough to eat which makes it do-able and enjoyable long term.

    Reply

Leave a Reply

Your email address will not be published.