Ketogenic Diets: High-fat or High-Protein – Q&A

Question: I’m familiar with the “true” ketogenic diet of 90% fat which historically is a medical diet used to assist in controlling seizure prone individuals, but it has the added advantage of being a fantastic way to shed weight while keeping the brain fed. In your RAPID FAT LOSS diet, you say it’s basically a ketogenic diet but without the dietary fat – why? If I were to choose between the 2 ketogenic diets, why choose 90-95% PROTEIN over 90-95% FAT????

Answer: The issue, as always, comes down to a matter of context.  The original epilepsy ketogenic diet was developed, as you note to control seizures.  And for whatever reason, at least one aspect of that was developing very, very deep degrees of ketosis.  For this reason, a very high dietary fat content and lowish protein intake is necessary.  This is for reasons discussed in Ketosis and the Ketogenic Ratio – Q&A.  Protein has about a half anti-ketogenic effect and too much dietary protein can inhibit ketosis.  Which makes the epilepsy diet not work.  So in that context, the diet had to be set up with very high fat and low protein.

And while such a diet may make people lose WEIGHT quickly, simply losing WEIGHT is not necessarily the goal.  Rather, the goal is (or should be) to lose FAT while maintaining MUSCLE mass.  I discussed this difference in some detail in the Rapid Fat Loss Handbook itself (as well as in every other of my books) or you can read the article What Does Body Composition Mean?

That is, people who want to change body composition aren’t just interested in weight loss per se, they want to maximize fat loss while (generally speaking) minimizing the loss of lean body mass.  And the simple fact is that a 90% fat ketogenic diet, due to the low protein content won’t do that.  Rather, dietary protein has to be set at a certain level to avoid lean body mass losses.

And since the explicit goal of the Rapid Fat Loss Handbook diet is to maximize fat loss (again while minimizing lean body mass loss) that also means cutting calories to the bone.  That means reducing dietary fat to minimal levels (only essential fatty acids).  And, mind you, such a diet would be wholly inappropriate (it wouldn’t work) for epilepsy treatment.

And that’s your answer.  If the goal were epilepsy treatment, the high-fat ketogenic diet would be the appropriate choice (I’d point anyone interested in this topic to The Ketogenic Diet: A Treatment for Epilepsy, 3rd Edition (Paperback) by Freeman, Freeman and Kelly).  But assuming the goal is maximal fat loss with no muscle loss (e.g. the goal of most who read my site), a higher protein intake is required and the very high-fat version of the ketogenic diet would be wholly inappropriate.

And, in the context of Rapid Fat Loss Handbook, given the explicit goals of that diet, that means keeping fat intake very low (limited only to essential fatty acids and the tagalongs that are unavoidable with whole foods).   Of course, more moderate ketogenic diets with sufficient dietary protein and higher dietary fat intakes can also be set up as described in my first book The Ketogenic Diet.  The rate of fat loss will simply be slower on such a diet due to the higher caloric intake.  But that may be a reasonable compromise for reasons discussed in Setting the Deficit – Small, Moderate, or Large.

Hope that clears it up and thanks for the question.



19 thoughts on “Ketogenic Diets: High-fat or High-Protein – Q&A

  1. I asked the question about FAT -vs- PROTEIN ketogenic diets and I just want to send you a huge THANK YOU! The clarity of answer was brilliant and as a result, I remain a loyal and impressed fan/student of yours! Danielle (;))>

  2. Lyle, how are you quantifying “high” protein? For example, I know that a lot of ketogenic dieters shoot for a split of 65% fat, 30% protein, and 5% carbs, so even though a majority of calories are from fat, protein is still high by i.e. USDA standards.

  3. Please read The Problem With Percentages Part 1-3, they are a useless way of setting up diets. Also read Comparing the Diets where I define MY terms for these things.

  4. Thanks, I appreciate it. I took a look at the articles you mentioned.

    In Comparing the Diets part 1, you said, “Since protein intake will always be set at about the same level (between 1.0-1.5 g/lb which is generally between 25 and 40% of total calories), I’m not going to bother defining terms for it. You can call it low-protein or high-protein or Susan for all I care; I consider it the proper protein intake and that’s all that matters”. So, with regards to, “assuming the goal is maximal fat loss with no muscle loss (e.g. the goal of most who read my site), a higher protein intake is required and the very high-fat version of the ketogenic diet would be wholly inappropriate”, would it be accurate to say that for setting up a ketogenic diet, one should get X low threshold of carbs, 1-1.5g/lb protein, and then can fill in the rest of the allotted calories with any combination of fat and protein?

  5. a high fat diet burns the most adipose tissue although it is not very palatable. a high protein one will burn fat fast but it can get rather dry and too nauseous like the high fat one. so the ideal according to vince gironda is a high protein high fat diet since it helps emulsify body fat. vince gironda’s ripped and shredded look was proof of this. the man would wrap a salami slice around a bar of butter and eat it. and he had these raw eggs which he mixed with cream and made milkshakes out of. as for the fruits and veggies he ate them raw. that comes fairly close to the paleo hackers diet. the man was was way ahead of his time. he even had rules of not drinking water with workout or meals.

  6. I thought protein gets turned into carbs before the body metabolizes it .How can u reach ketosis eating 90 percent carbs

  7. Ok so you’re saying to lose fat (let’s say me, female wanting to lose 35)…..and to also ” maintain/build muscle”, (gym 2-3 x per week) one should have a high protein, medium fat and low carb program, correct?

  8. No people, it’s HIGH fat, medium protein, and low carb. High fat so the body will start using it as the primary source of energy.

  9. Hi Lyle,
    I have two questions about ketogenic diet if you can answer.

    1) Is it possible to gain muscles on standard ketogenic diet? If the Macro ratio fat 65%, protein 33%, carbs 2%.

    2) What are the effects of ketogenic diet on testosterone levels? As i searched through the net, It is filled with contradictory reports.


  10. That’s not how this works. The fat component has nothing to do with the body’s shift to using fat.

    Chris, possible, yes? Optimal? I don’t think so. Small changes in testosterone don’t mean much regardless of the direction.

  11. I don’t mean to dredge up a relatively old topic, but I have an additional question about PSMF vs what I would call a “very low-calorie ketogenic diet”:

    A PSMF spares LBM with very few calories. However, there’s been a body of research that suggests that a ketogenic diet is generally very protein-sparing as well. If we were to compare two 1130kcal diets (using a lean male as a model)

    VLCK: 10g carbohydrates, 160g protein, 50g fat
    PSMF: 10g carbohydrates, 250g protein, 10g fat

    would we expect PSMF to be more protein-sparing?

    It seems to me that these both might be equally protein-sparing and lead to very similar rates of fat loss. The main difference I could see would be due to the “adaptation period” for ketogenesis, but literature doesn’t seem to support this as a large issue (based on a quick search).

    While I recognise characterising the VLCK as “ketogenic” is somewhat incorrect, the direction of this question is whether a VLCK-type diet would be 1) possible to implement for longer periods of time and 2) less psychologically difficult than the PSMF while maintaining most (if not all) of the benefits?

  12. Too much protein even with fat raises insulin levels and stores just like carbs. keto fails when too much protein eaten. not just for medical uses. Look up Dr Ron Rosedale.

  13. QUOTE:
    Teej on December 7th, 2014 4:39 pm
    Ok so you’re saying to lose fat (let’s say me, female wanting to lose 35)…..and to also ” maintain/build muscle”, (gym 2-3 x per week) one should have a high protein, medium fat and low carb program, correct?

    QUOTE 2:
    lylemcd on December 29th, 2014 11:38 am

    what is the consent here then?

    HOW should a keto diet be set up for max fat loss?
    I only get taught by paleo/keto people to raise fat more for more protein sparing and you cant gain weight on fat

    Doesnt a high protein low-mod fat + no carbs diet work?
    or is this then a pure protein->glucose-> =carbs diet?

    would a pure fat fast or something like that (90%fat 10%protein) for more days work?

  14. I am not saying anything, I am simply addressing whether a keto diet should be low protein or high fat. This is answering a question, not making a recommendation.

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