How to Know if Keto Is Right for You

As you’re probably aware, we’ll be releasing the second editions of our Muscle and Strength Pyramid books very soon. (January 3rd, a little later than planned, but there were a few things we wanted to further refine after discussing things in Auckland last week.)

As part of that promotion, we’ve decided to take ~10 sections from the books and release them as articles over the next couple of months. Each one of these articles won’t be for everyone, but I hope you find them interesting, and at least two or three exceptionally useful.

For the first one, we cover Keto. Why first? Well, it’s trendy, and I’m sick of answering questions about it. So, what does the science say about high-fat diets for people that lift like us? Enter my overly reference happy co-author, Dr. Eric Helms…

How to Tell if You Would Do Better With a Higher Fat-to-carbohydrate Ratio

Although it is not very typical among recreational and competitive bodybuilders and strength athletes to fall into this category, I think it is important to address how to tell if you are someone who would do better with a higher fat-to-carbohydrate ratio.

Now when I say “high fat”, I typically am referring to a fat percentage at or above 35% of total calories 1 as opposed to the aforementioned 15-30% recommendation (depending on whether you are dieting or gaining). In turn, keeping calories and protein the same, this higher fat intake leads to a generally lower carbohydrate diet compared to my earlier recommendations. And when I say “lower carbohydrate diet”, I’m referring to an intake that may approach as low as 0.5-1.5 g/lb (~1-3 g/kg) of bodyweight.

I am not necessarily referring to a ketogenic diet, which is extremely low in carbs, sometimes defined as 50g or lower 2. Ketogenic or ‘keto’ diets necessitate high fat intakes to maintain calorie balance, often at or above 60% of total calories. Keto diets have become quite trendy and popular as of late. Largely fueled by the idea that eating more dietary fat helps you to burn more fat as fuel, keeping you leaner along with the idea that you can only lose fat by keeping insulin low; however, these concepts aren’t quite accurate. Sure, you shift your body’s fuel usage more towards burning fat on a keto diet and insulin levels are lower, but since you are also consuming more fat, it doesn’t result in greater fat loss, and high insulin levels don’t predict body fat loss in a deficit 3.

However, this isn’t to say keto diets are useless, but rather have pros and cons. In the literature relevant to sport, exercise, and body composition, they are a mixed bag of positive, negative, and neutral effects:

  • There is an initial 1–4 week period of fatigue, irritability, and decreased performance when adopting a low-carb diet that subsides after adaptation 4 5.
  • In real-world settings, those who adopt low-carb diets typically increase their protein intake substantially, which can improve body recomposition, and increase satiety 6 7.
  • There is also an initial drop in hunger and increase in satiety independent of protein intake which lasts 1–4 weeks in most people and often results in a spontaneous reduction in calories and initial fat loss 8 9 10.
  • Low-carb diets on average are equally effective to moderate or high-carb diets for fat loss and muscle retention if protein is high 11.
  • However, we don’t have data on individuals getting very lean (such as bodybuilders), but observationally, higher placing bodybuilders typically consume higher carbohydrates relative to those who place lower 12.
  • On average, low-carb diets don’t seem to affect muscular performance after initial adaptation if training volume is low 13 14 15 16 17.
  • However, some individuals do better on lower-carb diets for both body composition and performance, while others do worse 18.
  • Lower carbohydrate diets might impede performance during high-volume resistance training 19 20.
  • Very low-carb diets may inhibit lean mass gains 21 22 23 24.  

As you can see, in general, for healthy, athletic individuals performing resistance training, the potential pros are typically not worth the cons of adopting a low-carb diet. However, there may be a time and a place for a high-fat, low-carb diet, and most 25 26 27 28 29 (but not all 30) research indicates that when there is a time and place, the utility for low carb diets exist among people who are insulin resistant.

So, how do you know if you fall into this camp and could benefit from that type of diet?

Well first off, let me state that the vast majority of people reading this book don’t fit the bill. Insulin resistance is typically only common among sedentary individuals with obesity (and even then it’s not everyone) and it is often a temporary state, as insulin sensitivity improves with a healthier diet and exercise. With that said, there are some instances where exercising, non-obese individuals can be insulin resistant, which might indicate a higher-fat, lower-carb approach would be better.

Insulin resistance is typically increased with age 31, a family history of diabetes 32 33, the presence of a condition in women called polycystic ovarian syndrome (PCOS) 34, or oligomenorrhea 35, which is represented by a menstrual cycle that occurs less frequently, specifically taking longer than 35 days to recur. While these first two factors can sometimes be affected by bodyweight and exercise, women with PCOS or oligomenorrhea typically have higher androgen levels (male sex hormones) than most women which predisposes them to be insulin resistant to some degree 36, regardless of activity or body-fat levels.

As you can see, in general, for healthy, athletic individuals performing resistance training, the potential pros are typically not worth the cons of adopting a low-carb diet.

Additionally, it is not at all uncommon for women with higher androgen counts to be disproportionately represented in athletic populations. This is even more so true in strength and power sports, which tend to have more women with higher androgen levels even compared to other sports 37. But, don’t despair if you need to modify your diet due to potential insulin resistance if you are a woman with PCOS or oligomenorrhea. The upside is that you likely have a higher than normal androgen count, which may mean you potentially perform better on average than other athletes 38. To further allay any fears, take heart that there is pretty convincing evidence that a higher-fat, higher-protein, lower-carbohydrate diet can be very effective for producing fat loss among those with insulin resistance 39 40 41 42 43 44 45 46.

Now, what if you are a male who does not respond well to carbohydrates or a female who does not have a diagnosis of PCOS or oligomenorrhea but still doesn’t do well on a high-carbohydrate diet? It’s not uncommon at all for people to believe this is the case, but not many people have objective data to base this feeling on. So, how can you test if a higher-fat diet truly would be better for you?

How to Systematically Test Your Tolerance

In an ideal world, you could simply go get some blood tests done to determine your insulin sensitivity, but that is not a typical option for many people. And even then, if a doctor finds you to be insulin resistant, the typical recommendations are to lose some weight, do some resistance training, and get active. Well, if you are reading this text you are probably already taking care of all of those things. So if you get that diagnosis, you’re left with no solution according to the doctor.

So beyond going to the lab, I think an even better way to test your response to a higher-fat, lower-carbohydrate diet would be to run some off-season testing and data collection on yourself. I would recommend taking about a month to consume a 40% fat diet, with the same protein and calories that you have normally been consuming. This would simply be changing the carb-to-fat ratio and nothing more.

Throughout this month, write down and record a 1 to 10 rating on mood, energy, and training quality each day. Mood and energy are pretty straightforward to define, but I’d like to clarify that gym quality is different than gym performance. We are not looking at your program, volume, or poundage of weights lifted (you can and should track this as well, but only if you keep your training approach broadly the same so you can compare like-to-like). Rather, this is more about how you perceive your overall effort and mental state during the day’s training. After a month of tracking mood, energy, and gym quality, take an average score of those ratings.

When that month is complete, repeat the process for another month while consuming a 20% fat diet and keeping calories and protein the same. But you aren’t done yet! If you really want to bring the scientific method into your assessment, I would recommend running this trial a second time, making this whole process a 4-month commitment. If the outcome is repeatable, you can be much more sure it wasn’t some other factor outside of your diet that influenced your scores. At the conclusion, you’ll be able to see if your ratings were higher for one diet or the other both times, and you’ll have your answer.

This might seem like a big hassle to find out whether you do better on a higher-fat or higher-carb diet, but in the off-season, it’s definitely worth it. Also, what’s stopping you? Keeping your energy surplus size, protein intake and training the same (while of course still trying to progress) for four months is not unreasonable. So do it, learn more about yourself! If you see a big difference in these ratings from your 40% fat months and your 20% fat months, you might be able to conclude that a higher-fat diet is something for you to stick to in the long term. Also, put it in perspective, if you plan on lifting weights and trying to improve your body composition for the rest of your life while you’re able (which if you’re reading this book I hope you are), then four months is just a drop in the bucket!


Thank you for reading. If you’d like to be notified when the second editions of our books go on sale, stick your email address in the box below.

– Eric and Andy

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  2. Feinman, R.D., et al., Dietary carbohydrate restriction as the first approach in diabetes management: Critical review and evidence base. Nutrition, 2015. 31(1): p. 1–13.
  3. Hall, Kevin D., et al., Calorie for Calorie, Dietary Fat Restriction Results in More Body Fat Loss than Carbohydrate Restriction in People with Obesity. Cell Metabolism, 2015. 22(3): p. 427–436.
  4. Chatterton, S., Zinn, C., Storey, A.G., Helms, E.R., The effect of an 8-week LCHF diet in sub-elite Olympic weightlifters and powerlifters on strength and power performance: A pilot case-study. Journal of Australian Strength and Conditioning, 2017. 25(2).
  5. Paoli, A., et al., Ketogenic diet does not affect strength performance in elite artistic gymnasts. J Int Soc Sports Nutr, 2012. 9(1): p. 34.
  6. Sawyer, J.C., et al., Effects of a short-term carbohydrate-restricted diet on strength and power performance. J Strength Cond Res, 2013. 27(8): p. 2255–62.
  7. Paoli, A., et al., Ketogenic diet does not affect strength performance in elite artistic gymnasts. J Int Soc Sports Nutr, 2012. 9(1): p. 34.
  8. Chatterton, S., Zinn, C., Storey, A.G., Helms, E.R., The effect of an 8-week LCHF diet in sub-elite Olympic weightlifters and powerlifters on strength and power performance: A pilot case-study. Journal of Australian Strength and Conditioning, 2017. 25(2).
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  10. Johnstone, A.M., et al., Effects of a high-protein ketogenic diet on hunger, appetite, and weight loss in obese men feeding ad libitum. Am J Clin Nutr, 2008. 87(1): p. 44–55.
  11. Hall, K.D., Guo, J., Obesity energetics: body weight regulation and the effects of diet composition. Gastroenterology, 2017. 152(7): p. 1718–27.
  12. Chappell, A.J., Simper, T., Barker, M.E., Nutritional strategies of high level natural bodybuilders during competition preparation. J Int Soc Sports Nutr, 2018. 15(1): p. 4.
  13. Chatterton, S., Zinn, C., Storey, A.G., Helms, E.R., The effect of an 8-week LCHF diet in sub-elite Olympic weightlifters and powerlifters on strength and power performance: A pilot case-study. Journal of Australian Strength and Conditioning, 2017. 25(2).
  14. Kephart, W.C., et al., The Three-Month Effects of a Ketogenic Diet on Body Composition, Blood Parameters, and Performance Metrics in CrossFit Trainees: A Pilot Study. Sports, 2018. 6(1): p. 1.
  15. Green, D.A., et al., A Low-Carbohydrate Ketogenic Diet Reduces Body Weight Without Compromising Performance in Powerlifting and Olympic Weightlifting Athletes. J Strength Cond Res, 2018. [Epub ahead of print]
  16. Sawyer, J.C., et al., Effects of a short-term carbohydrate-restricted diet on strength and power performance. J Strength Cond Res, 2013. 27(8): p. 2255–62.
  17. Paoli, A., et al., Ketogenic diet does not affect strength performance in elite artistic gymnasts. J Int Soc Sports Nutr, 2012. 9(1): p. 34.
  18. Chatterton, S., Zinn, C., Storey, A.G., Helms, E.R., The effect of an 8-week LCHF diet in sub-elite Olympic weightlifters and powerlifters on strength and power performance: A pilot case-study. Journal of Australian Strength and Conditioning, 2017. 25(2).
  19. Escobar, K.A., Morales, J., Vandusseldorp, T.A., The Effect of a Moderately Low and High Carbohydrate Intake on Crossfit Performance. Int J Exerc Sci, 2016. 9(4): p. 460.
  20. Cholewa, J.M., Newmire, D.E., Zanchi, N.E., Carbohydrate Restriction: Friend or Foe of Resistance-Based Exercise Performance? Nutrition, 2018. [Epub ahead of print].
  21. Vargas, S., et al., Efficacy of ketogenic diet on body composition during resistance training in trained men: a randomized controlled trial. J Int Soc Sports Nutr, 2018. 15(1): p. 31.
  22. Kephart, W.C., et al., The Three-Month Effects of a Ketogenic Diet on Body Composition, Blood Parameters, and Performance Metrics in CrossFit Trainees: A Pilot Study. Sports, 2018. 6(1): p. 1.
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  25. Pittas AG, Das SK, Hajduk CL, Golden J, Saltzman E, Stark PC, et al. A low-glycemic load diet facilitates greater weight loss in overweight adults with high insulin secretion but not in overweight adults with low insulin secretion in the CALERIE Trial. Diabetes Care. 2005;28(12):2939–41.
  26. Cornier, M.A., et al., Insulin sensitivity determines the effectiveness of dietary macronutrient composition on weight loss in obese women. Obes Res, 2005. 13(4): p. 703–9.
  27. Ebbeling, C.B.,  et al., Effects of a low-glycemic load vs low-fat diet in obese young adults: a randomized trial. JAMA, 2007. 297(19):2092-102.
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  38. Rickenlund, A., et al., Hyperandrogenicity is an alternative mechanism underlying oligomenorrhea or amenorrhea in female athletes and may improve physical performance. Fertil Steril, 2003. 79(4): p. 947–55.
  39. Pittas AG, Das SK, Hajduk CL, Golden J, Saltzman E, Stark PC, et al. A low-glycemic load diet facilitates greater weight loss in overweight adults with high insulin secretion but not in overweight adults with low insulin secretion in the CALERIE Trial. Diabetes Care. 2005;28(12):2939–41.
  40. Cornier, M.A., et al., Insulin sensitivity determines the effectiveness of dietary macronutrient composition on weight loss in obese women. Obes Res, 2005. 13(4): p. 703–9.
  41. Ebbeling, C.B.,  et al., Effects of a low-glycemic load vs low-fat diet in obese young adults: a randomized trial. JAMA, 2007. 297(19):2092-102.
  42. Le, T., et al., Effects of Diet Composition and Insulin Resistance Status on Plasma Lipid Levels in a Weight Loss Intervention in Women. J Am Heart Assoc, 2016. 5(1).
  43. Gardner, C.D., et al., Weight loss on low-fat vs. low-carbohydrate diets by insulin resistance status among overweight adults and adults with obesity: A randomized pilot trial. Obesity, 2016. 24(1): p. 79–86
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About the Author

Eric Helms

Coach, athlete, author, educator, and researcher, Eric has been involved in the fitness industry since the early 2000s. For the better part of his career he’s been a coach at 3D Muscle Journey, working with drug-free strength and physique competitors at all levels. A competitive athlete himself, he has pro status with the Professional Natural Bodybuilding Association and competes with the IPF at the international level as an unequipped powerlifter. Eric has published multiple peer-reviewed articles and writes for commercial fitness publications. He’s taught undergraduate and graduate level nutrition and exercise science and speaks internationally at academic and commercial conferences for fitness, nutrition and strength and conditioning. He has a BS in fitness and wellness, an MS in exercise science, a second masters in sports nutrition, a Ph.D. in strength and conditioning, and is a research fellow for AUT at the Sports Performance Research Institute New Zealand.

2 Comments

  1. Leo says:

    Dear Eric,

    thank you for the informative article! I still wonder about something (maybe it can even be some input for the book): You say that there is an “initial 1–4 week period of fatigue, irritability, and decreased performance when adopting a low-carb diet that subsides after adaptation” but then you recommend trying 40% for one month = 4 weeks and comparing it to 4 weeks of 20% fat. If someone who followed your recommendations was one of those people who need 3 to 4 weeks for adapting to low-carb, wouldn’t their comparison results be highly confounded by the adaption process? Why not 2 months low-carb and then 1 month high-carb (assuming that adaption is easier the other way around)? 6 months total is still a drop in the bucket, after all.
    Just something I noticed, I’ve never tried a low-carb diet though so maybe I’m overlooking something here.

    Kind regards from Germany
    Leo

    1. Eric Helms says:

      Leo, that specifically refers to ketogenic, or very low carb diets, closer to 60%+ calories from fat, that shouldn’t occur at all at 40% fat so not an issue!

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