Ketogenic Diet for Athletes

This week in my EXS 505 Sports Nutrition class, we were assigned two articles which discussed the ins and outs of the ketogenic diet.

Some of the findings could be of interest to a few of my readers, so I thought I would give you a peak at the findings. To be fair, I must tell you I read both of these articles with a bit of skepticism, so I am going to start with views coming in to reading these two. First, the articles are referenced at the end of this discussion (Paoli, et. al., 2015) and (Zinn, et. al., 2017). Feel free to check out both of these articles on your own if you want to take a deeper dive.

My bias

Admittedly my weak spot up until now is nutrition. I know the basics, but my passion lies in biomechanics, anatomy, programming, physics, and hypertrophy. I was definitely glad to be taking this course, and I have been nothing but pleased with the professor. For any of you who don’t know, I am on the long journey to obtain my PhD in Human Performance at Lenoir-Rhyne University with the first stop being a Masters in Exercise Science.

I am a huge follower of Dr. Layne Norton and Dr. Andy Galpin, and like most credible professors they emphasize calories in versus calories out. They don’t credit any of these diets with a lot more than just creative ways to limit calories. Most of everything I have read confirms what they are saying. However, I see now each diet has its pros and cons. Normally I am talking about small nuances, but sometimes, small nuances are all that is needed to make a big difference. Now let’s dive into what I learned.


Weight Loss (especially short term) – The biggest reason this form of diet seems to work is the natural appetite suppression as a result of the higher satiety of proteins, effects on appetite hormones such as ghrelin, and possibly a sort of direct appetite-blocking effect of KB. There is also reduced lipogenesis and increased fat oxidation, a reduction in respiratory quotient may indicate a greater metabolic efficiency in fat oxidation, and a thermic effect of proteins and increased energy usage by glucogenesis. (Paoli, et. al., 2015)

However, all of this could simply point to fewer calories. I mean, not many people can eat extra calories of just fat and protein. Obviously you can’t create fat storage if there aren’t extra calories to go around. Once again, if there aren’t a lot of calories from carbs, the body has to burn more fat for fuel. It really comes down to what one can sustain. If you lead a busy lifestyle that makes counting calories bothersome, this might very well be a great way to cut some pounds before a competition or to fit in that wedding dress.

One big reason for this being a great way to cut weight before a meet is because the initial weight reduction is related to a loss in body water through glycogen depletion. (Zinn, et. al., 2017) That is probably why there isn’t a lot of strength and power lost from this type of diet. Which of course brings me to my next point.

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Athletes Maintain Strength and Power – As of the Paoli, et. al. article in 2015, there was only research study that looked at KD’s (ketogenic diet) effects on strength and power. This was a study of 25 gymnasts over 30 days. They were provided 2.8 grams of protein per kg of body weight, less than 20 grams per day of carbohydrates, and the rest from fats with that amount being unlimited. The key for athletes is an adequate amount of protein must be used. In this study, the athletes maintained strength and power, while also maintaining lean body mass.

KD and Endurance – Here we had a bit of conflict in the two studies with Paoli, et. al., 2015 showing improvements in VO2 Max, improved fat oxidation with no detrimental effect on maximal or submaximal markers or aerobic exercise markers or muscle strength. It also showed cognitive improvements, which I will go over a bit later. Zinn, et. al., 2017 showed some decreases in performance which could have come from any of these factors:

  • It takes 7 days to adapt to a KD diet, and during those 7 days there will be a drop in performance.
  • Electrolytes need to be given during KD, both potassium and sodium.
  • The amount of protein is another key because the need goes up due to glucogenesis.
  • I would add that volume needs to be adjusted during the first seven days to account for the dip in performance, and it will take several weeks to recover from the overreaching.

Improved Psychological Markers – This one is my favorite. Here are a few of the improvements noted by both studies:

  • Improved rates of learning and memory
  • Increased synaptic plasticity, which when added to learning new skills or information, becomes a long-term advantage
  • Alleviates symptoms of depression
  • Improved sense of well-being
  • Higher rates of energy
  • Improved skin and hair

The only negative noted was Muscle Mass. A KD activates AMPK (5’adenosine monophosphate-activated protein kinase) which in turn inhibits mTOR (mammalian target of rapamycin) a mechanism necessary for regulating muscle mass. KD also blunts the IGF-1/AKT/mTOR pathway also reducing the possibility of gaining muscle mass. (Paoli, et. al. 2015) Of course all of this to say it is almost impossible to gain muscle in a caloric deficit. The bottom-line is an athlete needs to know if they way to pack on muscle, restricting calories in not a good idea.

Both articles painted a fairly good picture for KD. I am not 100% convinced it doesn’t boil down to calories, but it’s worth looking into. If you are an athlete cutting weight, it might be a good idea to spend 21 to 30 days with a ketogenic diet. You will shed some weight and stay strong. Below are a few questions we were asked to answer which might shed some more light on things. I hope you enjoyed!

Further Q&As

1 – State one surprising thing you learned from the Paoli et al. article. Note why it was surprising to you.
I was surprised to find out the KD could possibly be linked to multiple improvements in the CNS including multiple positive psychological improvements. We know the brain’s source of energy is normally glucose, so to see the body’s adaptive ability to not only survive without it, but possibly function even better, is quite mind-blowing. There were three main CNS improvements that caught my eye: improved behavioral and motor performance tests, learning, and memory, increased synaptic plasticity, and alleviated depressive symptoms. (Paoli et al., 2015)

If this is true, a KD could possibly make athletes smarter and increase the number of synapses in the brain. They are talking about increasing the network, which definitely intrigues me to read more and reach out to a few experts in the field. Athletes who need improved focus and reaction times could definitely benefit if this is the case. Also, this weekend I had the chance to work with a nonprofit, FitOps, which is an organization created to eliminate veteran suicide by teaching a three-week course designed to certify them as personal trainers, give them the business skills to be successful, and provides placement within the community. The finding regarding potential improvements in depression could be useful to the entire organization.

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2 – State one thing you question (because it goes against something previously learned or actually observed/experienced) or disagree with in either of the articles you were asked to read. (Remember to use in-text citations when referencing articles.)
The comprehensive article from Paoli interested me the most due to the low participation, and the average age of 50-years-old of the other article that I was assigned from Zinn (I mainly work with athletes between the ages of 16 and 30 – not age discrimination), and I was blown away by the findings regarding muscle mass. One of my earlier mentors, Charles Poliquin, was an early adopter of the LCHF diet approach. He was also a very famous strength coach for pro bodybuilders – not to mention some of the best professional and Olympic athletes on Earth. I watched him with my own eyes add muscle mass to athletes with KD plans. Therefore, Paoli’s statement regarding muscle mass is definitely challenging.

Hence, it appears somewhat contradictory there is widespread use of KD in bodybuilders also during “bulk up” periods, while all data regarding biochemical and molecular mechanisms suggest that it is very difficult to increase muscle mass during a KD; (Paoli, et. al. 2015). I have to assume it boils down to the characteristic reduction in calories due to appetite reduction from protein satiety and the overall appetite blocking effect of KB. However, I look forward to the opinion of my classmates and especially Professor Helsel.

3 – Did either of these articles change your views on ketogenic diets? (Explain by stating “how” and/or “why”). Remember to use in-text citations when referencing articles.
The intriguing aspect of the article by Zinn were the increases in overall well-being, recovery, improved skin conditions, improved memory and other cognitive abilities, and reduction in inflammation which was enough to interest me personally to try more of a KD. (Zinn, 2017). KD is becoming more and more popular, and I believe most diets are cyclical in nature. I pride myself in avoiding such fads. However, since I am a 47-year-old grad student, I have to at least look deeper into the cognitive and overall health improvements.

4 – If you have a client or athlete who wants to try a ketogenic diet to gain a competitive edge, what approach would you take with this client? (Include your rationale and whether you would provide the same advice/approach for all, or vary based on type of athlete).
Based on the information in both assigned articles, I would consider trying out a KD for a more optimal weight cut. I am the Head Coach of the inaugural Olympic Weightlifting Team at LRU. It’s of course a weight class sport, so optimal cuts to make weight at the top of a class while maintaining strength is a big part of the sport. It’s appealing to consider making a cut without restricting water and food, without using a sauna, and without spitting.

Our team has several 2024 Olympic hopefuls, so I can’t simply “try something” at a big national or international meet. I would try a KD out at a local meet beginning at 21-days out to get over the initial performance decrease experienced during the first few days. The main thing I would be looking for in the first meet is exactly how much weight is shed without further restrictions. The key is to get a potential percentage. Therefore, if the athlete drops 2% from KD only, I can assume 2% of a cut in an athlete who isn’t restricted to a KD will come from the KD alone. That will let me know how much needs to come from other means such as increased activity or further restrictions in calories – aka calories in vs. calories out.

Here’s an example. If I have a 73kg male athlete, I normally like him to stay within 2-3% of their bodyweight or 1.46-2.19kg. If we find a KD alone sheds 2%, then we can expect our athlete to easily shed the weight – and based on Paoli, keep his power and strength. This could be a really big advantage for our athletes as well as a healthy alternative. (Paoli, et. al., 2015).


Paoli, A., A. Bianco, and Grimaldi, K.A. (2015). The Ketogenic Diet and Sport: A Possible Marriage?. Exercise and Sport Sciences Reviews, Vol. 43, pp. 153-162

Zinn, C., Wood, M., Williden, M., Chatterton, S., and Maunder, E. (2017). Ketogenic Diet Benefits body composition and well-being but no performance in a pilot case study of New Zealand endurance athletes. Journal of the International Society of Sports Nutrition, 14:22 DOI 10.1186/s12970-017-0180-0

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