Metabolic Flexibility for Athletes – Part 2

March is Metabolic Flexibility Month. Honestly, I totally made that up and I have absolutely no idea if such a designation exists. We could also say that during the month of March we are trying to reset the metabolism to restore its efficiency in powering our athletic endeavors. 

In Part 1 of this series I explained that our goal as athletes is to use both of our fuel sources, fat and carbohydrate, most effectively. Intuitively, this might seem like a no-brainer, but balancing our energy substrates in the metabolism requires a bit of tact and art.

If we only eat a very low carb, higher fat diet, we’ll become very good at using fat for fuel. But, unfortunately, we will end up slightly downregulating our carb/glucose burning cellular machinery. Sure, the brilliant human beast tunes this back up fairly rapidly, but these shifts can require several weeks to optimize. Lifetime Athletes need to be metabolically efficient NOW, not in 3 weeks.

And if we only go high carb, low fat for an extended period, we create a carb-dependent, sugar-burning metabolism that can’t burn fat very well. We can’t access and use our bodyfat stores for energy very easily, and we are more susceptible to bonking. Plus, if the carbs are coming from highly processed food, we also run the risk of increasing chronic inflammation and compromising long-term health.

One distinction needs to be made before we go further in today’s discussion. The diet of someone who is in desperate need of restoring health, such as an obese individual with Type 2 diabetes, should look different than that of an already healthy, Lifetime Athlete. The diet for the ill person would most certainly involve some amount of both carbohydrate and caloric restriction, and the use of periodic fasting/time-restricted feeding. This is how lives are saved and health is restored. But that approach would basically be inappropriate for the athlete, whose caloric and macronutrient needs would necessitate a different picture in the kitchen. Let’s just keep in mind that we are focusing our discussion in this post on high performance athletic nutrition. 

Taking that last paragraph just a little further, health and performance can of course go together. But we are talking today about taking an already healthy person, keeping him or her healthy, and pushing into the performance realm. An unhealthy person has to get healthy first. You can’t train for peak performance when you are sick (in any form). This is called metabolic multitasking (by me) and it doesn’t work. Training won’t take and the body demands that you get it healthy first as a baseline before you pile on other assignments. Just trying to clearly frame our objectives.

In Part 1 I talked about the need to balance fuel sources (fat vs. carb) and I promise I’ll get to the specifics on that soon. But we need to review the value of protein as the macro that we don’t shift around as much. Whether you consider it a moderate level, or a high level, athletes need a consistent level of protein in the diet. Low protein diets have very little implication for lifelong health, and they are terrible for serious athletes. There is a lot of stigma surrounding those statements and protein unfortunately often gets a bad rap. So, in establishing metabolic flexibility, health, and peak performance…we need to embrace the consumption of protein and keep it at a consistent level for best results.

Protein is the building block for our muscles, tendons, ligaments, bones, and organs (among others). Those tissues are constantly repairing and rebuilding, especially in athletes. Keeping strong bones, glowing skin, and recovered muscles is key to health and performance and it requires consistent protein in the diet. Going “too low on pro” will diminish recovery and output capacity and ultimately contribute to weakness, sarcopenia (loss of muscle most strongly related to death) and osteoporosis. Gotta make this point that protein isn’t just for those who want to “bulk up.” It’s for anyone who wants to “stay up” as a Lifetime Athlete. 

One of the misconceptions about high protein consumption is that it will wreck your kidneys. This supposition is based on opinion not scientific fact. Organs typically get larger, stronger, more efficient, and heavier on high protein diets. With kidney health, we are often pointed toward glomerular filtration rate (GFR) and blood urea nitrogen (BUN) as markers of function. Both of these will go up on higher protein diets because the more efficient kidney is clearing more of the nitrogen byproduct of protein metabolism. The marker of concern should in most cases be creatinine (not creatine which is a supplement), which is a definitive sign of kidney disease. Obviously, if you have any concerns…consult with your licensed healthcare provider.

Protein also gets blamed for cancer and shorter lifespans. Much of this data is epidemiological in nature, based on surveys and associations, and from which it is inappropriate to draw conclusions on causation. There are many confounders in this area. However, we can be strongly supported in stating that a well-constructed diet, applied to a healthy athlete, that employs adequate (let’s not even say high…let’s use a better term) amounts of protein along with ideal meal timing, is key. Not only can this be safe…it goes beyond that claim to be better, best, and right. 

The last thing about protein before we move on is the source. It is a scientific fact that the most nutritious and bioavailable protein source for humans is animal protein, specifically that from red meat. The amino acid profile and associated micronutrients are superior in beef, lamb, wild game, and other red meats. Eggs are close and not far behind them is fish, seafood, poultry, and dairy for those who tolerate it. But we have to accept and respect that some folks, for any number of reasons which are entirely important and valid to each individual, are not going to consume meat. That’s fine…it is of course your choice. I’d throw in a lobby to study the most recent science on this topic that uses randomized controlled trials on both humans and the environment, and also to dive into the medical anthropology literature…but do as you must. The deal here is that if you are going to use plant-based proteins such as soy, hemp, rice, and pea powders (yes, you MUST supplement to get enough), you are going to need to eat a lot of it. Rice and lentils alone won’t cut it. The plant proteins are inferior in their amino acid profiles and also the human body assimilates a significantly lower percentage of the intake. Thus, even if two scoops of your favorite powder contains 30g protein (a good minimum target for a meal based on the literature), your body may only be able to absorb 20g of it. So pound the pro powder, accept that you are going to have some issues with bloating and gas, and stock up on heavy duty toilet bowl cleaner. Just sayin.

OK…let’s get into the recommendations for the Metabolic Flexibility Athletic Diet. I’ll list out a number of considerations and include some suggestions for specific objectives.

  • PBD: The Planet-Based Diet…I always start my discussions of food with this model. The PBD simply requires that you eat food that looks like it came from planet earth. Whole, fresh, natural, local, seasonal, etc. This is based on the JERF principle which says “Just Eat Real Food.” For the most part, avoid lots of packaged, processed, and lengthy label-bearing foods. Blueberries, broccoli, beef, salmon, potatoes — whatever you consider a superfood — I think you get the picture.
  • Calories: In most cases, you are going to want to stay relatively isocaloric. This means that you want to eat enough calories to fuel and recover, and remain weight-stable. You can calculate basal metabolic rate (BMR) and movement demands, but you will naturally have a sense for how many calories it takes to avoid losing or gaining weight. Keep in mind this may not be a static amount every day, as caloric needs will be affected by training loads and general activity.
  • Weight Gain: Also known as bulking or massing…we know that you need to combine resistance training, with optimal protein levels, in a diet that has a caloric surplus. It’s possible to gain mostly lean mass on such an approach if you progress very slowly, but in reality, the anabolic state in the body will generally see you adding a little fat and water weight with your muscle gains. 
  • Weight Loss: If a person has a significant amount of weight to lose, I don’t usually recommend they use this athletic approach, as I mentioned earlier. But if you just want to cut or shred a little, the trick is to be slightly hypocaloric for 3-6 days at a stretch. This should only be a few hundred calories per day under baseline, and again, keeping protein up to prevent muscle loss is key. After a few days, allow yourself a “refeed” opportunity, where you go back up to isocaloric or even slightly hypercaloric levels for a day or so. I’m not crazy about the term “cheat day” because it has negative connotations and often encourages people to just go hog wild and shovel in garbage. Just try to eat more healthy food, but if you need to have an indulgence to feel balanced, just do it and don’t worry about it. The reason for the refeeds is to prevent metabolic slowdown, which will happen if you stay hypocaloric for too long. Training will also suffer if you are not adequately fueled.
  • Fat: You need some. If you prefer plant sources, the fruit-based ones from avocado, olive, and coconut are good. If you go the animal route, much of that comes along with your protein choice, although butter, ghee, tallow, and lard can be options. 
  • Protein: While there are slightly different amounts recommended based on age and sport type, you can boil down the literature to make a generic target of about 1g protein for every pound of bodyweight. So, this 1g/lb goal is pretty substantial, and a 170 pound person like me would be shooting for 150-190 grams of protein per day. Since I’m a meat eater, and most meat has 7-8g of protein per ounce, an 8-ounce steak will give me a third of my daily requirement. It’s important that each protein serving be at least 30g and that it contains about 3g of the essential, branch-chain amino acid leucine, both of which are needed to trigger protein synthesis in the body. Older athletes need more.
  • Carbs: Getting most of them from plant sources is my recommendation, although there are some issues. Non-starchy, fibrous carbs like kale, cauliflower, and cabbage don’t provide too many calories and come with a lot of fiber. This can be good for satiety but can also put a digestive load on the body. Starchy carbs like root vegetables, squash, and fruit pack a little more caloric density. Everyone is different in tolerance levels and you know what you like and works best for you. I’m not a big grain pusher but if you prefer or do well with white rice, oatmeal, or even a little sprouted, or fermented bread…use your judgement.
  • Meal Frequency: This is where things start to get exciting. Athletes need to eat 2-4 meals per day. A one-meal-per-day intermittent fasting protocol is not appropriate for a hard training athlete. You can’t get enough of your calories or protein in just one meal, and despite its use by some athletes in endurance or alactic applications, I’ve found it to be suboptimal in the high volume/intensity trainer. Two meals can work for a lot of people, particularly if their training load is moderate. 
  • Meal Timing: Now it gets really exciting. It all depends on how much fuel you need, what your training is like, and what your goal (maintain, bulk, or cut) might be. An athlete who is going hypocaloric might actually benefit from eating only two meals in a 6-hour window, such as from 11am-5pm. But a really hard trainer or big gainer might do better with 4 meals spread over a 12-hour window from 7am-7pm. The important thing here is that we want to preserve some of the benefits of the nightly fast, by trying to keep feeding within a 12-hour span, preferably when the sky is light, which chronobiology research suggests improves health and sleep. But if an athlete has evening practices, there may need to be exceptions made. 
  • Macro Distribution: This is the key point — literally the secret — of metabolic flexibility. Your a.m. meals need to be high fat/low carb and the pm meals should be low fat/high carb. A breakfast or lunch that is mostly fat and protein will not spike insulin very much, and you’ll get that extension of fat-burning efficiency. You’ll have great satiety and stable blood sugar levels. Then, in the afternoon and evening, meals that are higher in carbs but lower in fat will help you to restore your glycogen levels effectively. The key is not to eat fat and carbs together to any great degree, which has been proven to sort of confuse the metabolism and not enhance this fuel partitioning ability. Mixed carbs and fats, particularly if processed (think most junk food) have also been associated with most health problems.
  • Macro Ratios: Pursuant to the info above, the early-in-the-day meals should try to hit a fat/pro/carb ratio, in terms of percentage of calories, of about 60/30/10. Later in the day, you’ll reverse it at about 10/30/60. This can be done on 2, 3, or 4 meals, and I’ll provide some examples in table format below.
  • Tracking: At least for a few weeks, I recommend tracking your food as you go through this process. My favorite app (free) is cronometer and you can get an idea of calories, macros, and nutritional value of your food quite easily. Over time, you’ll establish your favorite dishes/meals and know almost exactly how they stack up.
OPTIONBREAKFAST (8:00 am)LUNCH (11:30 am)DINNER (5:00 pm)
Omnivore4-egg omelette with small amount salsa and dollop of sour creamPower green salad with grilled salmon, cheese, and olive oilGrilled chicken breast with white rice and steamed brocolli
Carnivore (ish)3 strips bacon or two sausage links with 2 eggs over easyDouble cheeseburger in lettuce wrapLean round steak trimmed of visible fat with roasted yams
VeganSmoothie with coconut milk, rice protein powder, and half avocadoWrap with low carb tortilla, sauteed veggie protein, cabbage, and olive oilBaked vegetable and tofu casserole

Obviously, the options above are meant to be very general examples. You’ll notice that the breakfasts and lunches are in the high fat/low carb range and the dinner is the reverse. You can see that it’s tough (but not impossible) to get enough protein on a vegan diet and it’s hard to keep the carbs down. On a 2-meal plan, I’d just eat one of the breakfast or lunch choices before noon and call it good. For a 4-meal option, you can simply stretch out the window a bit and add a fourth platter. Also, the portion sizes would be individualized to fit your appetite and caloric needs…just keep the ratios similar. For me, I’d probably do fine with any of these options but would double the portion sizes. You can also add in some other foods to keep color, flavor, and texture enjoyable. 

This is a really simple and safe protocol that is geared toward tuning up metabolic health and restoring metabolic flexibility. Using this method will help you to dial in your nutrition and get your body efficient at fuel partitioning, or being able to flip the switch and burn fat or carbs as a primary fuel source. Any healthy athlete can give it a try. I encourage you to experiment with this plan and make it your own. And reach out to me with questions or to share your results with our community.

If you’d like to take a deeper dive into performance nutrition and training, join me at The Hard to Kill Workshop in Bozeman, MT on Feb 29th. Cheers!

Share a comment or question!

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: