KETO AND LOW CARB FOR CYCLISTS | Dr. Kyle Pfaffenbach | Ask a Cycling Coach 535

Ask a Cycling Coach Podcast
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Summary
Keto diets or chronically low carbohydrate diets are not beneficial to performance according to the current body of peer-reviewed research.

A periodized low carb approach can be favorable for performance, body composition goals, and general health. Implementing a periodized low carb approach is most practically done by increasing carbohydrate intake from whole grains, fruits, and vegetables in the two meals prior to high demand training, fueling with adequate amounts of carbohydrate on the bike (60, 90, 120g/hr depending on the athlete), consuming a recovery drink with a 4:1 ratio immediately post-exercise, and then reducing carbohydrate levels thereafter.

When adjusting carbohydrate levels in this periodized low carb approach, your protein and fat goals stay the same. Shoot for 1.8-2.2g/kg of body weight for protein, and 1.4-1.6g/kg of body weight for fat.

A low carb meal may contain as little as 40g of carbohydrate for some athletes, while it may be higher for others.

Intermittent fasting has proven health benefits for the general population and could benefit some athletes as well, but it should be considered as a final modifying piece to an already optimized and solid platform of nutrition and training, not as a replacement for it. Intermittent fasting and fasted training can pose significant risks to nourishment, training, and health if done incorrectly.

Coach Jonathanā€™s Note:
Great to have Dr. Pfaffenbach address a listener question on low-carb training! We do a brief overview of the research, then Kyle goes full magic school bus and gives as an extremely practical and in-depth explanation of carbohydrate and fat metabolism before getting into how he personally leverages periodized carbohydrate fueling with his athletes. Hope you find it helpful!

// TOPICS COVERED

(00:00:00) Welcome!

(00:00:32) Listener Question on Low Carb Diets and High-Intensity Training

(00:02:41) Hostā€™s Personal Experience with Low Carb and Keto Diets

(00:03:29) Research and Studies on Low Carb and Keto Diets

(00:05:13) Mechanisms of Fat Oxidation and Performance

(00:09:30) Deep Dive into Carbohydrate and Fat Metabolism

(00:31:29) Practical Applications for Athletes

(00:40:39) Understanding Body Composition and Success

(00:42:17) Glycogen Storage and Technology

(00:46:01) Periodized Carbohydrate Intake

(00:51:24) Balancing Nutrition and Training

(00:59:59) Fasted Training and Marginal Gains

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Really enjoyed this cast. One of the main takeaways I got was the fixed fat macro target. Iā€™ve targeted these ranges in protein for some time, but targeted percentages for fat. Then backfilled the rest with carbs.

What thatā€™d look like is, say, 140g protein, 25% fat, 50% carb (round about) on a rest day and higher carb percent on days I train.

Taking the above fixed rate actually reduces my carb percent by quite a bit on off days. For example, an off day I hit about 2400c for the day. So

Protein: 2.0 * 75 = 150g = 600c
Fat: 1.5 * 75 = 113g = 1,013c
Carb: 1013 + 600 = 1613. 2400 - 1613 = 787c /

So:

Protein: 25%
Fat: 42%
Carb: 32%

On training days, I burn about 1k more (long rides excepting). And the ratios would be:

Protein: 18%
Fat: 30%
Carb: 52%

Still higher on the Fat % than I usually target.

I find it interesting since my lifting coach recommends the same high protein, but 20-30% fat, with 30 being the upper, to most easily maintain a low BF%. This strategy did work for me when I was cutting.

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Really enjoyed this podcast. Thank you for clarifying so many of my questions about carbs and eating for both health and performance.

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This was a good one. Cheers chaps.

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I understand the recommendation to reduce insulin / glucose spikes during normal activity. But, isnā€™t reiterating ā€œto have your recovery drinkā€ basically counter to that point? The recovery drink would theoretically add yet another spike. Can you have it both ways? Either weā€™re minimizing spikes or adding moreā€¦ Kind of confusing in my opinion.

This was a great topic that is very applicable to probably a lot of the TR crowd.

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Are you assuming that a recovery drink, right after finishing a workout, will cause a release of insulin, or is that your experience? My experience, the few times I checked it after a 2.5+ hour ride with a fair amount of intensity included, is that my blood glucose level is pretty forgiving of some carbs. But, I donā€™t seem to have insulin insensitivity issues. The protein in the drink probably aids in reducing spike, too.

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Yea, I assumed that a 4:1 carb to protein ratio would spike glucose. Especially in liquid form where it is rapidly digested. No, I havenā€™t tested this with a CGM, but assuming you fueled the workout properly, I wouldnā€™t think youā€™d be low on Glucose post ride.

2.5 hour ride it definitely makes more sense, but at some point it may trigger a spike. I just did a 75 minute SST ride. and finished at 10am. Lunch is at noon. What should I do? It felt moderately difficult.

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If you fueled the ride, youā€™re probably ok to wait until lunch. I look at the calorie burn and how much I ate pre- and during, to decide. You could do a small recovery drink, or eat some berries if you feel like you need it. Itā€™s my understanding that the insulin response during and right after exercise is different as they noted in this bit I grabbed from an article from totalendurancenutrition.com (it came up first):

"When you might consider using drink to help support recovery ultimately depends on several factors:

  • If you are short on time
  • Are you traveling (and have limited access to food)?
  • If you just completed a particularly long and/or hard session
  • How long youā€™ve got before your next session

A good rule of thumb is this: If it is going to be more than 1 hour before your next meal or snack, then opting for a recovery drink is a great way to kickstart recovery. If youā€™ll be eating soon after finishing your session, then getting the right nutrients from food to optimise your recovery will be sufficient.
ā€¦
The first hour or so after training is a really important time to consume both carbohydrate and protein because the body is essentially ā€˜primedā€™ to absorb and use/store these nutrients.

Muscle glycogen replenishment happens at a high rate in the hour after exercise due to increased sensitivity of muscles to the hormone insulin, which increases in the blood when we consume carbohydrate and helps glucose be taken up into the muscle. After a hard and/or long session, muscles can also be in a glycogen-depleted state, making them more receptive to glucose uptake through a mechanism independent of insulin. In simple terms, following exercise more glucose is drawn into muscle because there are two systems operating to make this happen. Once in the muscle, the glucose is more rapidly converted to glycogen because after exercise there is also heightened activity of glycogen synthase, the enzyme responsible for making glycogen.

If you consume some protein with carbohydrate, then this effect is enhanced even more! Studies show that consuming carbohydrate and protein together lead to high muscle glycogen replenishment than carbohydrate ingestion alone.

And of course, simply consuming protein following exercise is a good thing to do anyway because protein provides the amino acids that the body needs to repair muscle and for the process of adaptation (e.g. building new muscle fibres or mitochondria to support energy production)."

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Does anybody know why itā€™s a good idea to eat enough protein to cater for my excess 10kg of flab?

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-You can eat as much as you want. If itā€™s too much for you, they usually provide a range of g/kg.
-An extra 20g of protein is probably better than an extra 10g of fat. (if you shoot for a consistent total calorie amount)
-Iā€™ve heard plenty of professionals say that, for prescribed macro amounts, they use total body weight to keep it simple (i.e., a lot of people donā€™t know how much muscle mass their body isā€¦which may or may not require a different prescription), so they offer the calculation based on total body weight.
-Kyle Pfaffenbach several times has said if youā€™re trying to lose weight, to calculate the protein by mutiplying the Protein grams/kg x (your weight - 5 lbs), and suggests you do that in 5 lb increments (so if youā€™re 130lb but want to get to 120lb, youā€™d calc the protein based on 125lb until you hit 125lb on the scale, then start calculating it based on 120lb desired weight).

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Is something off in that formula?

Protein = protein g/kg x (weight-5lb)?

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I donā€™t think so. I was just trying to illustrate what I tried to say in long form. I didnā€™t put it in equation format so I wouldnā€™t have to also add the conversion factor to convert weight in pounds to kg :grin: (to me it is implied, but I guess I should account for everyone not having done daily calculations with units for decades ). Iā€™ll try again

daily protein intake in grams = prescribed protein in g/kg x 0.4536 kg/lb x (total weight in lbs minus 5 lbs)

eta: Kyle says to eat 2g/kg of protein; I weigh 130 lb, but would like to get down to 120lb, and Kyle says to figure the protein based on 5 lbs lighter than I am no; so,

2.0 g/kg x 0.4536kg/lb x (130 lb - 5 lb) = 113.4g protein per day

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Lol. Iā€™m lost. Maybe itā€™s just me. :sign_of_the_horns:

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I think the issue is he kept using g/kg and kg/lb in the equation in the wrong place so it was making it look like extra steps.

Reading his equation in words he is saying subtract 5 from your weight (130) in lbs. Then multiple 125 times .4536 (lbs to kg multiplier). Then he multiplies that number 56.7 times 2 for 113.4

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To be fair, I added that last bit (the ā€œeta:ā€ sample equation) after Pbaseā€™s last post (for the benefit of any future readers)

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Ahh, got it. Bolding above is mine. I see now that you were including both the formula and the values in one line. Thanks. I get it!

(Recommended g/kg daily protein intake) x 0.4536 x (weight-5) = recommended g protein per day

2.0 x 0.4536 x 125 = 113.4g

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Oops, except when total energy content is held constant:

Glycogen synthesis was not significant (āˆ’0.05, 95% CI = āˆ’0.23 to 0.13) in CHO-PRO compared with CON when matched for energy content.

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Looking at my tracker, the last week Iā€™m 12% fat, 71% carbs, 16% protein. I donā€™t understand the low carb fetish at allā€¦

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I think the primary issue is that you donā€™t want to spike insulin. And, post-workout, this should not happen with the consumption of glucose because the glut4 transporters would already have been translocated to the cell membranes through the act of muscle contraction, so a release of insulin to cause the translocation is not necessary.