Carbs vs. fat research update

It’s not often that revolutionary research comes around, but at the Eleventh International Society of Sports Nutrition (ISSN) Conference and Expo I think it’s safe to say some interesting science was presented.

These results of high vs. low carb diets may not come as a surprise to those who followed my Bayesian PT Courses, but if you’re still stuck in the high carb bodybuilding dogma, this may open your eyes. We’ll have to wait until the full texts are published and I’d like to see these results replicated, but for now the abstracts will have to do. I’ve abbreviated the abstracts for your convenience.


research update



The effects of ketogenic dieting on skeletal muscle and fat mass

Jacob T Rauch, Jeremy E Silva, Ryan P Lowery, Sean A McCleary, Kevin A Shields, Jacob A Ormes, Matthew H Sharp, Steven I Weiner, John I Georges, Jeff S Volek, Dominic P D’agostino, Jacob M Wilson


This is the first study ever to research very low carbohydrate ketogenic dieting (VLCKD) relative to a traditional high carbohydrate diet in resistance trained athletes.


Twenty-six college aged resistance trained men volunteered to participate in this study and were divided into VLCKD (5 % CHO, 75 % Fat, 20 % Pro) or a traditional western diet (55 % CHO, 25 % fat, 20 % pro).

All subjects participated in a periodized resistance-training program 3x per week.

Body fat and lean mass were determined via dual xray absorptiometry (DXA), while muscle mass was determined via ultrasonography analysis of the quadriceps.

All measures were taken at week 0 and 11.


Lean body mass increased to a greater extent in the VLCKD (4.3 ± 1.7 kgs ) as compared to the traditional group (2.2 kg ± 1.7).

Ultrasound determined muscle mass increased to a greater extent in the VLCKD group (0.4 ± 0.25 cm) as compared to the traditional western group (0.19 ± 0.26 cm).

Finally fat mass decreased to a greater extent in the VLCKD group (-2.2 kg ± 1.2 kg) as compared to the traditional group (- 1.5 ± 1.6 kg).


Note: From what I gathered during Jacob Wilson’s presentation when we were both lecturing for the Norwegian Academy for Personal Training, this study included a carb-up at the end. This probably explains why lean mass rose so much in the ketogenic diet group, i.e. it’s glycogen and water, not muscle mass, though before the carb-up the ketogenic diet group still had better muscle growth and fat loss.


These results indicate that VLCKD may have more favorable changes in LBM, muscle mass, and body fatness as compared to a traditional western diet in resistance trained males.



Effects of a ketogenic diet on strength and power

Sean A McCleary, Matthew H Sharp, Ryan P Lowery, Jeremy E Silva, Jacob T Rauch, Jacob A Ormes, Kevin A Shields, John I Georges, Jacob M Wilson


Note: To my knowledge this is simply more data from the study above.


The 1 RM bench press increased in both the LCKD (10.3 ± 4.4 kg) and western (9.5 ± 4.0 kg).

The 1RM squat increased in both LCKD (12.7±5.9kg) and western (15.2±7.6kg).

The wingate peak power increased in both the LCKD (51.8 ± 64.7 W) and western (80.5 ± 66.8 W).


A LCKD can produce similar strength and power gains to a western diet.

Note: I’d say that the Wingate test results are clearly in favor the western diet and it’s safe to say the same holds for all sorts of anaerobic-endurance exercise. (See the image below if you don’t know what a Wingate test is: it’s a brutal test of anaerobic power capacity on an ergometer.)


Wingate test



The effects of very high fat, very low carbohydrate diets on safety, blood lipid profile, and anabolic hormone status

Jeremy Silva

Note: To my knowledge this is simply more data from the study above.


There were no differences in any of the safety parameters measured (CBC / CMP) in either the VLCKD or traditional group.

Total cholesterol increased slightly in the VLCKD group, while it decreased in the traditional western group. However, this rise was driven by an increase in HDL in the VLCKD group (6.69 mg/dl) compared to the western (-1.6 mg/dl) with no changes in LDL.

Triglycerides were significantly higher in the VLCKD group (29.3 mg/dl) than the western (-8.4 mg/dl).

Total testosterone increased significantly in the VLCKD diet (118 ng/dl) as compared to the western (-36 ng/dl) while insulin increased significantly in the western group (3.7 uIu/ml) compared to the VLCKD (.1 uIu/ml).


This study data suggests that a VLCKD is safe. In addition, this diet strategy improves testosterone values while simultaneously increasing insulin sensitivity. Lastly, even though the total cholesterol increased in the VLCKD group, their HDL drove this response. Athletes looking to optimize their hormone levels while employing a safe dieting strategy can use a VLCKD.



Effects of dietary macronutrient distribution on resting and post-exercise metabolism

Eric T Trexler, Abbie E Smith-Ryan, Hailee L Wingfield, Malia N Melvin, Erica J Roelofs


Previous research has demonstrated that habitual dietary macronutrient distribution affects energy substrate utilization at rest and during exercise. The primary purpose of the current study was to examine the relationships between habitual baseline macronutrient intakes, expressed relative to bodyweight and percentage of total energy intake, and metabolism at rest and after exercise in women.


Twenty recreationally active women (Mean ± SD; Age 24.6 ± 3.9 yrs; Height 164.4 ± 6.6 cm; Weight 62.7 ± 6.6 kg; BF% 28.2 ± 4.8%) volunteered for the current study. Prior to metabolic testing, participants completed strength testing to determine their 1RM for six resistance exercises and completed a 3-day dietary log. Participants were provided with detailed instructions for accurately logging food intake and portion sizes, and instructed to record their regular food intake on two week days and one weekend day. Logs were analyzed using The Food Processor software (ESHA Research, Salem, OR, USA). Body composition was determined using dual-energy X-ray absorptiometry (DXA). Exercise was prescribed using baseline strength data and heart rate reserve calculations. Respiratory exchange ratio (RER) and resting energy expenditure (REE) were analyzed via indirect calorimetry (Parvomedics TrueOne 2400) before exercise (PRE), and during minutes 0-10 (IP), 25-35 (30min), and 50-60 (60min) post-exercise. Bivariate correlations and independent samples t-tests were completed using SPSS software (Version 19.0; IBM, Somers, NY, USA). Participants were stratified based on fat intake as a percentage of total caloric intake (high fat > 35% of total kcals, n=11; low fat < 35% of total kcals, n=9) and relative to bodyweight (high fat > 1.3 g/kg, n=11; low fat < 1.3 g/kg, n=9). Consent to publish the results was obtained from all participants.


A significant inverse relationship between carbohydrate (CHO) intake (g/kg) and REE was observed at IP (r=-0.539, p=0.014), 30min (r=-0.569, p=0.009), and 60min (r=-0.577, p=0.008), with a trend toward significance at PRE (r=-0.413, p=0.07).

Participants consuming > 35% of kilocalories from fat had a significantly higher bench press 1RM (p=0.048) and lower RER at 30min (p=0.033) and 60 min (p=0.033).

Participants consuming > 1.3 g/kg of fat per day trended toward lower fat mass (p=0.09) and BF% (p=0.07).


Results indicate that baseline macronutrient distribution impacts post-exercise energy metabolism in women. Higher fat and lower CHO intake was associated with greater post-exercise REE and lower post-exercise RER, indicating greater fat utilization. Higher fat intakes may also influence resistance exercise performance and body composition; participants with higher fat intake had a greater bench press 1RM and trended towards lower indices of adiposity. These results suggest that the relative contributions of CHO and fat to total caloric intake may have significant implications for metabolism and body composition in women.


  1. raphaels7 says:

    In the study:

    The effects of very high fat, very low carbohydrate diets on safety, blood lipid profile, and anabolic hormone status

    “Triglycerides were significantly higher in the VLCKD group (29.3 mg/dl) than the western (-8.4 mg/dl).”

    How can this be? Did you check the full-text?

    • Interesting indeed, as low carb diets usually decrease triglyceride levels. I’d speculate that it’s the result of the fatty acid balance in their diets. Since HDL increased as well though, I doubt this could be considered a serious risk factor.

      • Ryan Lowery says:

        This is during Week 11 when we saw increases in triglycerides. Triglycerides stayed about the same during the intervention however this profound increase was seen following the rapid reintroduction of carbohydrates. Very interesting. Stay posted for the manuscript (it just got submitted for publication)

  2. Landon Poburan says:

    I would like to know if calories were equated in the “The effects of ketogenic dieting on skeletal muscle and fat mass” study?

  3. Chris Fisher says:

    Would love to see results and tests for DOMS (Delayed Onset of Muscular Soreness) on LCHF. My experience on VLCHF as an older athlete is a significantly reduced effect thus allowing me to exercise both more effectively and efficiently with the attendant gains. In my case, roughly, I’ve gained 4% in muscle mass, lost 40% body fat and gained 18% in strength.
    My understanding is that the VLC leads to a low insulin response which in turn leads to a much lower Internal Inflammatory State, also known as the Silent Killer (assumingly more significant the older one becomes), and thus lack (in my case) of post exercise soreness.

  4. Chris Fisher says:

    Correction, 8% body fat lost! (was half asleep)

  5. Vinay says:

    What’s the likely explanation for why the high fat/low carb led to more muscle mass and less fat compared to the tradional diet? I assume in both cases the diets were relatively “clean”, as were the exercise choices?

  6. Jesse says:

    I’m extremely curious as to what the diet looked like for subjects who stuck to it for 11 weeks: I have no clue how someone can run a vlcd while keeping the fat intake high unless they were eating tons of steak, eggs, all sorts of oils, and cheeses. In other words, I have a very hard time believing the subjects adhered to the diet for 11 weeks, even with weekly refeeds.

    • Chris Fisher says:

      Jesse, been on the VLCHF for two years now. Quiet easy maintaining my required food intake (2900 cal/day)over the last few months (see above), used MyFitnessPal to track ratios and amounts, really love the great food and don’t miss sugars in the least :-).

      • Jesse says:

        Congrats on that. I’m curious as to the food choices you use. Doesn’t sound to me like vegetables, steak, cheese, steak, eggs, and a ton of oil is a diet that can be maintained for more than possibly one month. I will be the first to say I cannot stick to a diet for more than one month, meaning I had to have that cheat day or two. I’m not the type to completely destroy it by letting myself go and have five cheeseburgers, 3 milkshakes, and five large fries.

        • Gasper says:

          Have been on keto for 3 years now. When you are adapted it is easiest diet to folow.With time you don’t care for other foods. I was obsessed with carbs before but now I do not care for them.. Eggs, meet, fish, butter, olive oil, cheese…

    • As Chris said, many people have no problem adhering to ketogenic diets for months on end. It’s really mostly people that haven’t actually tried it that think it’s not sustainable, but of course it’s not for everyone. Most of my clients aren’t on a ketogenic diet.

      • Vinay says:

        In wondering though if one really needs to cut back on carbs that much to get the same benefits. Ie if I keep my carbs at around 20-25%, still keep relatively high % of fats. Ie is there a ceiling beyond which more fat/ less carbs doesn’t really add additional anabolic or fat loss benefits. The study seems to have focused on two extremes.
        I personally like carbs so would hate if I had to cut them to <30g for no additional perceived muscle build or fat loss benefit.

        • The current research does not allow us to discriminate between keto and regular low carb diets in this regard, but my theory is that ketosis is not required. The mechanism for the increased anabolism seems to be fat mediated, so I tend to side for an optimum fat intake and reserve keto diets for special circumstances.

          • Landon Poburan says:

            You mentioned that you feel it is more fat mediated for increased anabolism, what do you feel is optimal fat intake? Some people use % but that varies based on caloric intake. Do you have a suggestion? For example I am 190lb eating 3250 kcal and eating 95g fat. Do you feel there is a ceiling for fat intake in regards to it not being any more anabolic or possibly negative side effects?

          • It depends on your carb tolerance and which kind of fats you’re consuming. See my interview by Ian McCarthy for more information.

          • Vinay says:

            Thanks Menno, very helpful – your theories are good enough for me! I’ve been on v low carb and high fats before and personally haven’t seen better body comp or other benefits in myself vs going higher in carbs (~75g to 175g, cycling), but still high good fats, med-high protein and keep total kcals the same. On the latter I was still able to cut to ~7.5% bf, which was good enough for me.

  7. Michael Cocchiola says:

    What’s your opinion on cycling calories (high/low) for training days and rest days? Many people go very low fat and very high carb on training days to prevent fat gain, but is that unnecessary and would increasing dietary fat or just eating more balanced lead to better results?

  8. Thomas Hemming says:

    Hi Menno,

    Thanks for sharing these result, indeed very interesting. In my own experience it is certainly possible to build muscle and strength on a very low carb diet.
    My question is if there are any places where you talk about which fats are the best to consume? I’m thinking in terms of saturated, monounsaturated, polyunsaturated, SCT, MCT and LCT. E.g. some say that nuts are bad because the omega6:omega4 ratio is off but is this really an issue as so many other omega6 sources are cut out? Basically I’m just very curious to hear what kinds of fat are the best to eat.

  9. Erik G says:


    In your opinion, would restricting carbs on a bulk give any disadvantages (compared to a more carbohydrate based diet) when following a resistance-training program with pretty high frequency and volume?
    I simply enjoy eating fats over carbs, and therefore I would like to hear your experience with this type of diet on a bulk. If u have any of course.


  10. Rita says:

    Great article! I’m wondering whether you have any information on the effects of a ketogenic diet on Thyroid hormones? I have been eating a ketogenic diet before and it was great but my TSH-hormone increased a lot and my T3 and T4 decreased (was on the limit to be hypothyroid) even though I have a healthy Thyroid gland with no problems with this earlier.

    • In healthy individuals, a ketogenic diet causes a change in the pattern of thyroid hormone expression, including a change from T3 to T4 production, but actual metabolic rate is unaffected.

  11. Rita says:

    Can also mention that once I upped my carbs my Thyroid-stimulation hormone went down to normal levels, as well as T3 and T4 increased.

  12. v Seth says:

    Great article Menno come out with more like these! Would love one about IF and about ckd,tkd etc.I was wondering what your thoughts as are on if excluding carbs from your diet has any negative effects on Testosterone compared to including them? Being Ultra low carb vs including some.

  13. Ben nz says:

    Is a Diet like that optimal for a healthy lean football player that wants to put more mass ? I only have tickling joints due to not enough pulling, that is being corrected, but I feel like i should drop inflammatory stuff, and libido is lolbad

    Something like 0 starch, 100g of carbs from fruits and vegs, 150g of proteins, 200 fat ?

  14. Joe says:

    It’s worth taking this research with a BIG grain of salt.

    All but perhaps the last of these finding is brought to us by the crack team at UT, who also brought us this little gem:

    All this time, all we’ve need to do is gulp down HMB for steroid-like gains! Who knew?!

  15. .v says: would this be of concern or would you say it is fear mongering?

    • The most blatant cherrypicking I’ve seen in a long time, e.g. the testosterone research is clear that fat intake is almost linearly related to testosterone production, but here they cite acute endurance training on the free testosterone to cortisol ratio, which only shows that you need carbs for endurance training in order to avoid high cortisol production.

      • .v says:

        and this is why i love u…

        on a tangent would you say that low carbs are needed for sex drive (if fats and calories are high enough of course)?

        also if someone goes on a very low carb diet (ketosis like levels) but has protein too high for them to be in actual nutritional ketosis, would they be able to get the neurotransmitter benefits (i.e. serotonin) from the protein consumption? I would see this as a true hack, that someone who lifts can get everything that carbs have to offer besides taste without actually having carbs!

  16. Kam D says:


    Fantastic research once again. So glad I found your website. The nutrition/health field is riddled with cherry picked associations.

    I love how everything you provide is evidence based with studies backing up everything.

    I am trying to work out the details in my house to take your next course. :)

  17. Marc says:

    So I’m still unsure of what all this means. Given calories and protein are kept the same, is there some sort of metabolic advantage to a higher fat/lower carb ratio? If that is the claim what about all the bodybuilders over the years that get shredded on high carb/low fat diets?

  18. Phil says:

    Menno, very interesting study. Apparently Wilson did some funny things with heavy carb loading for the keto group before the DXA scans were done, this may be the reason the lean mass gains were 4 kg in 8 weeks. This is probably also the reason this study never made it through peer review. Do you happen to know more details about this?

  19. Jani Valtonen says:

    Thank you for this article. What do you think, how does gonadotropin work in ketogenic diet? There’s this study argumenting we need gonadotropin-releasing hormone (GnRH) to get testosterone to our body. And to have GnRH we need glucose? But somehow it seems that everything works differently on ketogenic people because we have so much testosterone anyway?

  20. Marc Persson says:

    Where can i see the studies? If no studies are available, this is nothing but claims. (Read this on my phone, don’t know if thats why i can’t see them.)

  21. omen says:

    Menno I have seen you state that Carbs are not essential for anything. However neither is Monosaturated and Saturated fats, which I know you recommend to consume.

  22. CD says:

    so which diet you are on? :)

  23. Curtis Pai says:

    The thing I find craziest about all of your Research and studies is that if you keep reading through the comments, you learn and absorb so much information. Incredible thanks a lot.

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