Carbs, Keto, Insulin And The Alternative Hypothesis, Part One

While I was on the cruise, this YouTube video made a splash. It was hailed as the death of the carbohydrate-insulin hypothesis. Take a look:

Several readers emailed to ask what I thought, and I replied that since I hadn’t seen the study itself, I had no opinion yet … although little alarm bells went off in my head when I saw that the researcher being interviewed was Kevin Hall. If the name sounds familiar, perhaps it’s because he was the lead researcher on a recent study that was reported in the media with headlines like FOR FAT LOSS, LOW-FAT DIETS BEAT LOW-CARB DIETS HANDILY, NEW RESEARCH FINDS.

I wrote about that study in this post. The (ahem) low-carb diet provided 140 grams of carbohydrate per day – including 37 grams per day of sugar.  Yeah, just like Dr. Atkins recommended.  The low-fat diet, meanwhile, was truly a low-fat diet: just 7.7 percent of calories from fat.

Hall responded to that criticism by saying he had to choose a moderate-carb diet to keep protein constant across both diets.  Several readers responded to that response by producing (within minutes) two low-calorie diet plans, one very low-fat, one very-low carb, both with identical protein.  So Hall’s explanation doesn’t hold up.

The diets lasted a whopping six days each (everyone in the study was supposed to do both diets), and the difference in weight loss was a non-significant one-tenth of one pound.

In the full paper, I saw that 19 people completed the sort-of-low-carb diet, but only 17 completed the low-fat diet … and yet the researchers didn’t restrict their comparison to the 17 people who completed both diets, and didn’t provide individual data for any of the dieters. And the paper included this strange paragraph:

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.

My impression was that Hall designed the “low fat beats low carb handily” study to get the results he wanted — perhaps assisted by tossing out a data point or two.  Clear outliers, ya know.

Those complaints about his earlier study notwithstanding, if a study is conducted and analyzed honestly, then the data is what the data is. Like I said, I haven’t seen the study he’s explaining in the video. But Dr. Mike Eades took a careful look at the video, screen-capping some of the charts so he could analyze them, and also dug up the abstract. I’d suggest you read his entire post, but here’s the first punchline:

In the video, Hall declares that the study shows there’s no metabolic advantage to a ketogenic diet. Got that? No metabolic advantage. But the title of the abstract is … wait for it … Energy Expenditure Increases Following An Isocaloric Ketogenic Diet in Overweight And Obese Men. And a sentence in the abstract clearly states:

Therefore, an isocaloric ketogenic diet was associated with increased energy expenditure of ~100 kcal/d.

Perhaps it depends on your definition of “advantage,” but that sounds like an advantage to me.

After watching the video and reading Dr. Eades’ post, here’s my opinion of the study: I don’t really care either way. As Paul Jaminet pointed out during a podcast, there are more than a million diet studies in PubMed. You can find almost any result you want. I’ve seen studies in which a lower-carb diet led to more weight loss, even on the same number of calories. This one, for example:

On the 1,800-kcal reduction diet consumed over a 9-week period, diet A contained 104 g carbohydrate/day; diet B, 60 g; diet C, 30 g. The three-man subgroups were matched as closely as possible on the basis of maintenance caloric requirement and percent body weight as fat.

Weight loss, fat loss, and percent weight loss as fat appeared to be inversely related to the level of carbohydrate in the isocaloric, isoprotein diets. No adequate explanation can be given for weight loss differences.

But I’ve also seen studies in which restricting calories led to the same average weight loss whether the diet was low-fat or low-carb. And I suppose if someone did enough digging, he could find a metabolic ward study where people lost more weight on a high-carb diet than a low-carb diet.

Again, I don’t really care. People don’t live in metabolic wards where their food intake is carefully controlled. They live in the real world. And in the real world, people respond to their appetites. For many people, myself included, switching to a low-carb diet resulted in (after years of frustration) losing weight without going hungry.


Of course I consumed fewer calories than I burned, you @#$%ing moron! That is always HOW we lose weight. And consuming more calories than we burn is always HOW we gain weight. But as I’ve said many times (and will keep saying until I’m blue in face), HOW we get fat isn’t the same as WHY we get fat.

I tried explaining the difference in this post by pointing out that HOW your toilet overflows (more water entering the bowl than draining out) isn’t the same as WHY your toilet overflows (a clog in the drain pipe). But toilets don’t have appetites, so let’s use (or re-use) a different analogy:

Suppose I have a rather serious alcohol problem that’s affecting my life, and not in a good way. After getting a snootful, I tend to become annoyed by friends and acquaintances who haven’t fully recognized my superior understanding of all things and thus have the gall to disagree with me now and then. So I get in touch to correct their erroneous beliefs and offer strongly-worded advice on how they should fix their lives, careers, diets, social media sites, professional relationships, or whatever – for their own good, of course. As a result, my friendships soon have the life expectancy of a second lieutenant on Iwo Jima.

Waking up with a hangover one afternoon and recognizing the problem may actually be with me instead of everyone else, I vow to limit my drinking to two scotches per day from now on. But no matter how sincere the promise, one drink always leads to another and another and another. Next thing I know, I’m getting punched by strangers in bars for reasons I can’t accurately recall. I curse my lack of discipline and wonder what the @#$% is wrong with me. I really, really, really want to drink less but can’t seem to do it. So I turn to science.

“Why do I drink so @#$%ing much?” I ask the science world.

“Because you’re an alcoholic,” the researchers answer.

“But WHY am I an alcoholic?” I ask.

“Because you drink too much,” the researchers answer.

See the problem? The amount of alcohol I consume only explains HOW I get drunk. It doesn’t explain WHY I get drunk. Because you drink too much isn’t an answer; it’s simply a restatement of the problem.

But now let’s suppose something amazing happens. After making significant changes in my diet, I find my urge to drink has dwindled. I can go out on Saturday night and have two glasses of wine with dinner, then stop. That craving for a third, fourth and tenth drink just isn’t there anymore. (Long-time readers may recognize that this is partly a true story.)  It’s not a character issue, because I’m not resisting an urge.  The urge is gone.

“Why don’t I get rip-roaring drunk every time I drink like I used to?” I ask the science world.

“Because you don’t drink as much as before,” the researchers answer.

“But I used to have this powerful urge to keep drinking, and now I don’t. So it must have something to do with biochemical changes brought on by the new diet.”

“No, no, no,” the researchers reply. “We’ve done studies on this. If we get 20 people drunk for a week by having them knock back 10 scotches per day, then lock them all in a cell and give them two drinks per day for another week, they’re all equally sober at the end of the second week. Doesn’t matter if they’re alcoholics or not, and it doesn’t matter if we feed them chips or cheese while they’re drinking. So obviously the cause of alcoholism is drinking too much, and the cure is to drink less. It’s simple.”

That two-drink-per-day study may exist, and it may have been honestly conducted and analyzed. But I don’t care. It doesn’t tell me diddly about WHY alcoholics drink too much. It also doesn’t explain WHY a change in diet caused my appetite for alcohol to shrink.  Everyone remains equally sober on two drinks per day isn’t useful information for a problem drinker trying to walk past an open bar.

Several studies, including this one, have demonstrated that switching to a low-carb diet causes many people to eat less – even though they’re not counting calories or trying to eat less:

On the low-carbohydrate diet, mean energy intake decreased from 3111 kcal/d to 2164 kcal/d. The mean energy deficit of 1027 kcal/d (median, 737 kcal/d) completely accounted for the weight loss of 1.65 kg in 14 days.

If you spontaneously cut your calories by more than 1,000 per day – and yes, end up consuming fewer calories than you burn as a result – then something very positive has happened to your metabolism.  But I don’t think it’s quite as simple and direct as Fewer Carbs => Less Insulin => More Fat Burning.  Or to state it in reverse, I don’t think getting fat is as simple as More Carbs => More Insulin => More Fat Storage.

This is already getting to be a long post, so I’ll explain why I believe the “alternative hypothesis” needs some revising in my next post.


69 thoughts on “Carbs, Keto, Insulin And The Alternative Hypothesis, Part One

  1. Alex

    For me, the only discernible function of reducing carb intake is lowered appetite. If I keep carb intake below the threshold of starting the blood sugar roller coaster, carb binging stops, and I eat less. I know our bodies are not simple bomb calorimeters, but my body does appear to respond quite linearly to calories consumed, and some years ago, when a habitual eating pattern was keeping me a bit heavier than desired, weeks of calorie counting brought the weight down and reset the eating pattern. I easily endured that enforced caloric restriction because my diet was low enough in carbs to not stimulate appetite. But, that’s irrelevant to someone like Jimmy, who clearly has a metabolism that is vastly different from my own, and unlike me, has a strong genetic predisposition to obesity. Where Jimmy and I may be similar is that we both have body fat set points that the body won’t go below, no matter what; even as a skinny boy, I always had a softly padded physique. I would die of starvation before I’d ever see six-pack abs.

    It strikes me that there’s a strong collective desire to dumb it all down into a one-size-fits-all soundbite diet, and there are just far too many variables for that to happen. People need to figure out for themselves what works or doesn’t work for them, and it would be nice if they had enough self-restraint to not project their N=1 experiences as some kind of universal truth from upon high.

    1. Tom Naughton Post author

      Agreed. There’s no reason to believe people whose ancestors lived in different parts of the world with different food sources should all thrive on the same diet.

      I once starved myself down to 165 pounds. My body decided it would rather burn muscle than those last bits of fat around the waist.

      1. KidPsych

        I do wonder how much selection bias impacts our views on diet. I’ve done tremendously well with paleo/primal foods (and not well at all on a vegetarian diet), but I do try to keep my mind open to other possibilities for other people.

        1. Tom Naughton Post author

          You certainly have to take the placebo effect into consideration. But I felt lousy on a vegetarian/low-fat diet even after going into it expecting to feel good.

          1. KidPsych

            I went on a vegetarian diet in the 80’s, so I didn’t have any information relating depression and diet. (I’m sure it existed, but there was no web to browse.) It’s the only time of my life in which I’ve experienced extended sour mood.

            As to higher fat, lower refined carb, the physical effects (coupled with weight training) have been hard to ignore and unlikely related to a placebo. My wife keeps trying to get me to lift my shirt up around friends. As I approach 50, I’m getting 6pack abs for the first time in my life. I showed a picture of me from a few years back to a friend at work. I wasn’t in particularly bad shape, but I was slightly doughy. Her response – “you look kinda inflamed.” Which I thought was an interesting comment outside of the context of diet and inflammation on her part.

            Thanks for your great work here.

            1. Tom Naughton Post author

              I’m pretty sure the pictures of me now vs. me in my 30s aren’t the result of placebo effect either.

            2. Walter Bushell

              If it is a placebo effect, then forward the placebo!

              The word on sugar — Whether it’s a drug or not is up for debate, but it acts like it is. I know people who just lose control when presented, but perhaps if they ate more fat they wouldn’t be. Like someone here who dropped out of alcohol addiction simply by going low carb high fat.

  2. Bob Niland

    As far as I know, the full paper for that NUSI trial is not yet published. It’s clear from Hall being contradicted by his own presentation materials, that we (as usual) cannot rely on headlines, press reports, press releases, unscripted breathless interviews with agenda-bearing PIs or even paper abstracts.

    Let’s wait for the paper, then dive in. I suspect that things were learned, and it may turn out to have been strategically beneficial that one of the PIs is a prominent CICO advocate.

    Also, this was reportedly a pilot study, with more trials to come.

    1. Tom Naughton Post author

      Gary Taubes invited researchers who have previously opposed low-carb diets — Hall among them — to run NuSI studies to avoid having their work dismissed as having a pro-low-carb bias.

  3. Perry

    Hi Tom,

    One problem with “studies” is the time frame they span which is generally short at least for ward studies. So changes to energy burned, the “out” side of the equation, may not reflect what would happen to the organism’s energy expenditure if allowed to run over time.

    If one starts eating less, for whatever reason, a drop in whole body metabolism is usually going to happen but short term studies won’t show this. So in effect, one important variable is ignored as though it can be expected to remain constant over time, a very faulty assumption in my opinion.

    If a change in diet raised ones metabolism instead of dropping it, over time, we would see a weight drop (at least in fat) even assuming calories were held constant or even if they were increased but increased less than the gains in energy expenditure brought on by the new way of eating. So eat the same number of calories, or even more calories, but burn proportionally more and lose fat all without an exercise increase.

    Unfortunately, it is this view of “metabolic advantage” that gets kicked to the wayside in favor of some cellular level advantage/disadvantage discussion that has been raging for years and again highlighted in this study.

    I wonder if instead of going low carb you had adopted some metabolism improving steps instead like not eating seed oils (pufas), setting proper circadian rhythms, and tending to stress factors, you would have seen the same benefits you attribute to low carb?

    1. Tom Naughton Post author

      Or simply cut all processed foods in favor of real foods — which would of course mean eliminating the seed oils. More on that in the next post.

  4. Perry

    Said from a different perspective, I wonder if you had fixed your mitochondria would you have achieved the same benefits you attribute to low carb.

  5. Kathy in Texas

    No offense to the Older Brother, but damn, I’m glad you’re back. These are the posts (along with the farm reports) that keep me coming back to your blog. I needed a reminder not to go against my body’s natural rhythm of not eating breakfast. I’ve gained a few by trying to force an early-in-the-day meal which – for me – simply results in eating more, not less, throughout the day. Thanks again for your perspective and I’m looking forward to the next post.

  6. Dianne

    Sadly, I know that in my pre-Fat Head days I’d have read the headline and the first few paragraphs, believed the “experts,” figured carbs were not the problem, and downed a bag of pretzels, wondering why I couldn’t stop eating the stupid things and feeling like a weak-willed failure. Now when I see something like this I start asking questions — what kind of study? For how long? Just how many carbs do they consider low carb? Who were the subjects? Who funded the study? Etc. Thanks again, Tom.

    Gotta run up to Sprouts Market now — I’m out of bacon and down to my last few free-range eggs. If I don’t start the day with fat and protein, my appetite becomes deranged and I crave carbs the whole durned day, with the result that my arthritis goes bonkers, my brain fogs up, and I accomplish practically nothing all day. Who needs that — especially when a breakfast of bacon and eggs is so much tastier than a bowl of oatmeal? Life is better now!

    1. Tom Naughton Post author

      I believe there’s a Sprouts opening soon in Franklin. I’m looking forward to checking out the selection.

      1. Dianne

        I love Sprouts. Because they don’t carry a whole lot of stuff nobody needs and don’t carry fifteen different brands of everything, they are much smaller than most food markets. But they have a great selection of produce and meats, and the Sprouts 1 mile from my house carries a lot of the things for which I used to have to make an 18-mile round trip to Whole Foods.

          1. Kelly Lynn

            From my experience with Sprouts, they are far cheaper in many aspects then Whole Foods. My only complaint is different locations don’t carry the same things, and some have a deli and others don’t. I believe the deli is a new addition though, so hopefully that will expand to other locations.

          2. j

            It’s way cheaper than whole foods. They have self serve bulk bins with all kinds of nuts, flours and seeds for less cost than pre packaged items. As well as many good specials on meats, veggies, etc..
            Love sprouts..

          3. Randal L. Schwartz

            Sadly, the sprouts in Culver City has a full wall of “greek yogurt”, but not a *single one* of them is full fat. They do have Kerrygold cheese and butter though. Nothing like extra sharp Kerrygold cheddar.

            1. Galina L.

              I live in Florida, regular groceries stores started to sell a full-fat Fage Greek yogurt.

            2. Nowhereman10

              Your Sprouts is very different from where I live. We not only have a wider selection of yogurts but within the last two months has started carrying raw milk, which by the way, flies off the self it’s been selling so well.

            3. BobM

              We don’t have Sprouts where I live, but Whole Foods is now carrying at least two different yoghurts made with milk from 100% grass fed cows. The milk from grass-fed cows is still ridiculously expensive (as is the yoghurt), but the only other option is to buy your own cow.

          4. Dianne

            Welllll — I haven’t done any item-by-item comparisons, but it might be slightly cheaper. Hard to say, because the things I tend to buy there are often higher-priced items anyway — organic veggies, grass-fed meats, Kerry Gold butter, vitamin and mineral supplements, egg-white protein powder, organic taco shells, etc. Maybe I should price some random items at Sprouts, and then go see what Whole Foods charges for the same things. I’m pretty sure Sprouts isn’t any more expensive than WF, anyway, and they certainly give you a more pleasant shopping experience. For one thing, our WF recently added another layer of shelves on top of their old ones, and at 5’1″ I’m always having to ask some total stranger, “Excuse me, but would you be so kind as to reach me down two of those jars of almond butter.” Or whatever. Probably wouldn’t be a problem for you, but annoying for me.

            1. Curtis

              I noticed a couple of months ago that my local Costco is carrying Kerry Gold butter now. Costco is becoming one of my regular stops for specialty items, like, coconut oil, avocado oil, coconut flour, chia seeds and I just picked up some hemp seed this month. Not sure what to do with them yet…put them in a smoothie or smoke them?!?!

          5. Carl G

            They are cheaper here in Colorado Springs for most things and I would say they pretty equivalent in produce quality to Whole Foods.

            1. Bret

              Another place I’ve discovered recently is Natural Grocers. Good prices and very nice selection.

              One complaint I’ve had about Whole Foods, Trader Joe’s, and Sprouts is that their animal food quality is subpar (at least in the locations I’ve visited). Lots of “organic” labels, but little to no grass fed/pastured/etc. WF sold one brand of pasture-raised eggs at a 30% markup over my local Fry’s (Kroger’s western name brand).

              At Natural Grocers I found plenty of grass-fed beef products (including liver), grass-fed dairy (milk, butter, cheese), and pasture-raised eggs. They weren’t dirt cheap, but they clearly beat Whole Foods.

            2. Carl G

              I mostly get meat in bulk from local farmers now (main reason because it tastes better), but I will take a look a Natural Grocers for filling in here there.

          6. Susan

            I love my Sprouts. Get cheap and tasty lamb chops and pork chops. And the pork tastes like what my mom used to serve. Not that dry shoe leathery stuff we’ve been getting since saturated fat became the devil. And the produce is much fresher — and cheaper — than what I get at my local Ralph’s or Stater Bros.

      2. Lori Miller

        Sprouts is great, and they’re cheaper than Whole Foods (although that isn’t saying much). Yet it doesn’t beat the tiny co-op that’s in the middle of a “food desert” here in Indianapolis. The co-op carries pastured lard, bacon, jowl bacon, lamb bacon, sage sausage, chorizo sausage, kitchen sink sausage, hillbilly sausage, pizza sausage, fatty beef, beef tongue, chicken feet, chicken livers, beef liver, and rennet if you want to make your own cheese. They have deli meats and cheeses from animals raised on small local farms–and they’ll make you a sandwich on gluten-free bread. There’s not much on that list at the Sprouts–or anywhere else–where I used to shop in the Denver area. And the jowl bacon, I’d never even heard of.

      3. Bob Niland

        Another low key chain worth checking out is Aldi’s. Attractive prices. Theire stock is increasingly organic and non-GMO.

        They now take credit cards (were until recently cash-only). Be sure to take a quarter for the shopping cart (like at the airport).

        Scored some very nice avocados there lately.

        1. Lisa

          Love Aldi’s. Organic produce and their store brand products are often organic, non GMO. At prices well below standard. They recently carried pastured butter as a buy out and always carry grass fed ground beef that is really reasonable.

    2. JillOz

      Re what you’ve learned from Tom, I too have learned to ask questions about studies.

      I have recommended to Tom that, in addition to all the other titles he adopts, he also should call himself a science communicator.

  7. Nowhereman10

    This sort of thing isn’t limited to nutritional sciences. I just recently came across this little gem on how a whole psychology field is being turned on its head:

    The problem? While the researchers dillengently did their clinicals, they also discarded any studies, both correlative and clinical that did not prove their hypothesis.

      1. Walter Bushell

        Well obviously if the results are wrong, the research was done incorrectly and the study can be ignored.

          1. Walter Bushell

            We certainly can disagree with the interpretations and “scientists” have been known to make up alleged data out of their imagination or random number generators.

      2. Nowhereman10

        Yes, and if the article is correct, there is a bias amongst the science literature publishers since they often only published papers that showed positive results rather than negative ones. It was when the researchers (presumably more objective and honest ones) tried to reproduce the previous results they wound up not being able to sometimes and other times they did. So when they looked back, they found the bias discrepancy towards the tendency to discard results not showing a positive, and thus most of that field of psychology is now rendered null and void.

        And given this, it makes me wonder how much of the nutritional research has been hampered by this same bias phenomena among the science literature publishers.

    1. Tom Naughton Post author

      I think there’s more to it than that. You’d also have to ask why reducing carbs reduced your appetite.

      1. Troy Wynn

        Low carb = lower post meal and fasting blood sugar = lower insulin = mobilization of fat for energy = less need for food as body fat stores and dietary fat provide the fuel. Consequently lower hunger.

        If insulin remains high in the blood, my understanding is fat cells go into lock down mode: only let the fat in (store), not released for energy (out).

        1. Tom Naughton Post author

          The revision part is that higher carb meals don’t necessarily mean higher circulating insulin throughout most of the day. More on that later.

          1. Mike

            It seems to me that the other part of the equation is that eating more frequently keeps insulin averaging higher all the time. There are people who report good weight loss results with intermittent fasting, while not reducing carbs. Eating lots of little meals during the day will tend to keep insulin up, even if your carbs are reduced.

            One of the advantages of being fat adapted though, is that it’s much easier to wait a long time between meals, without having your energy sag, so the two strategies self-reinforce.

            1. Tom Naughton Post author

              I think that’s one problem many people have with high-carb diets: blood sugar goes up, then crashes. Then they need to eat again.

            2. Jake

              If by “high carb” you mean white pasta, bread and sugar, then yes.
              These foods are junk. Just like oils and processed meats. They all cause bad things with insulin and blood sugar.

              Whole food carbohydrate with fiber doesn’t cause the spike/crash problem in most people. The bigger problem is, people don’t know how to eat.

            3. Tom Naughton Post author

              Yup, it’s the acellular (fiber removed, no intact cells) carbs that have screwed us up. Avoid those, and most people don’t overdo the carbs in the first place. Or as I put in Q & A on last year’s cruise, we don’t count how many carbs our daughters eat, because if you take away 300 grams per day of cereal, bread, sodas and candies, kids aren’t going to replace those carbs by eating 10 sweet potatoes.

            4. BobM

              I found much improved everything by adding intermittent fasting (IF) to my low carb diet. Much better BP reduction, satiation, weight loss, everything. I was originally eating LC with 5-6 meals a day, as the “experts” said we had to eat so many meals per day.

              Dr. Jason Fung has a good blog, accompanying videos, and even a book (The Obesity Code). After reading his blog, I started IF and haven’t looked back. Down about 50 pounds (20-25 with LC, the rest with LC + HF + IF), 43 inch waist to 36, etc. Now breakfast is rare and most times makes me feel worse and hungry (even a low carb breakfast with eggs and bacon). If I eat breakfast, I try to avoid eating lunch. I feel better not eating breakfast after my morning workouts. Odd.

  8. Walter Bushell

    This is a formatting disaster! Every other comment comes out as blacktop on a dark gray background rendering every other comment invisible. (In Safari)

    In Chrome it’s a light gray background. HMM!?

    OS(e)X 10.7.5

  9. tony

    Tom, I have a dim opinion of diet studies because the participants are usually volunteers, not a random sample of a properly defined population (a block, city county, state, country, etc.). Therefore each and every study’s results will only apply to the participants in the study, not the world’s population.

    For example, while a low carb diet reduced your desire for alcohol to 2 drinks per week, William Banting stated in his classical “Letter on Corpulence, Addressed to the Public” that in a typical day he has 5-6 drinks.

    1. Tom Naughton Post author

      That may have been his normal intake both before and after. What changed for me was the craving for more drinks than I intended to consume.

    1. Tom Naughton Post author

      I’ll write more about it later, but I don’t think it’s as simple as high carb = high insulin.


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