How many carbs should you eat? And when should you eat them?

This is part 3 of a 4 part series on blood sugar. In part 1, we address the basics of blood sugar and why everyone, including athletes, should care about their blood sugar levels. In part 2, we discussed the importance of testing your own body to specific carbohydrates and how exactly to do that. In this article, we are going to address how to use carbohydrates in your diet so they fuel your life instead of create disease. There are some very important things to address before we jump into the details of how to properly “carb cycle.” Starting with what carb cycling is and why this even matters?

What is carb cycling?

Carb cycling is a method of eating in which you go back and forth between higher carb days and lower carb days. There may even be days that are “keto.” Typically, “carb cycling” is a method of eating used by athletes where they consume higher carbs on days that involve more intense exercise. In my experience, this method of eating works best for athletes who are already fat adapted. This creates an ideal situation to burn fat on days of low intensity training (which is usually 80% or more of an endurance athlete's training) and strategically use carbohydrate on days when you want to include more high intensity. This type of eating can ensure you are getting enough carbohydrate in your diet to aid in recovery, but not so much that your body starts to prioritize sugar for energy over fat.

I realize that the terms "low" and "high" are relative. That's because it really does depend on how "fat adapted" you are. For an athlete who has trained their body to efficiently burn fat, it is not uncommon to see them eat 120-150g of carbohydrate on a "high" carb day and 50-80g of carbohydrate on a "low" carb day.

You can test your body in a lab to discover exactly how "fat adapted" you are by getting a lactate threshold test completed. This type of data can help you learn what a "high" and "low" day might look like for you.

Periodization

If you are an athlete, or have even been an athlete, you should be fairly familiar with periodization. Periodization is a strategy in which you target varying specificity, intensity and volume at specific times of year to improve your performance. By training at the right intensity and volume at the right time of year for your sport, you increase the chance of obtaining your performance goals. 

Successful athletes do not typically train at the exact same paces at the exact same distances all year long. For example, if you are training for a marathon, most well built training plans will have a period where you focus on building your endurance, which is typically separate from a time of building speed, which is all together separate from a time of recovery. 

Of course there is a blend of endurance, speed and recovery in each microcycle but the general focus for each block of training at different times of year is also different. Nutrition can, and should be treated the same way (curious about this approach to training, check out my post on building an annual nutrition plan that lines up with your on and off seasons!). When training volume is high, the amount of food you eat and the types of foods you eat will be different than the amount and types of foods you would eat during a recovery block. 

Once you understand how important it is to change your diet in order to support the different demands your sport can bring throughout the year, it makes it much easier to understand why learning to “carb cycle” can be important to your performance and recovery!

You Need Carbs… but the right ones and in the right amounts!

Carbohydrates are the preferred fuel for sports performance. However, depending on your gender and size, your body can only store approximately 1,400-2,000 calories of sugar in your liver and muscles. 

That means that if you train or race for longer than 90-120 minutes, it is likely that you’ll deplete most of your stored sugar and be left low in energy (aka- BONK!). And since we know that your gut can only absorb about 1g of carbohydrate across the gut lining into the blood each minute, that means that you are likely burning more carbohydrates than you can consume.  Unless you have 1. done the metabolic training to burn more fat and 2. keep your heart rate low enough that your body utilizes more fat than carbs. 

The FASTER study showed that you can train your body to do this with diet. There have been numerous other studies that have since then been published that support the same outcome. 

I bring this important fact up because your need for carbs depends greatly on how much fat you are able to burn. If you are metabolically flexible and can easily tap into your own stored body fat, you conserve your stored sugar and don’t require as much exogenous consumption as someone who mostly burns sugar. 

Since the bulk of the questions I get from clients around how much carbohydrate to use and at what times are from “fat adapted” athletes, that is what I am addressing here. If you have not done the work to get fat adapted, this model will likely not work for you and you will need to consume more carbohydrates more frequently to keep your energy levels up. 

However, if you’ve fat adapted, let’s talk about how and when you should use carbs to fuel your life and performance.

As we discussed above, as your physical training changes, so should your nutrition. In order to keep this relatively simple, I’m going to break down how much and when I advise using carbohydrates per training cycle.

Base Training

In base training, we are typically focused on building the cardio engine, creating injury resilience (which usually means strength training for most endurance athletes) and focusing on metabolic flexibility. I wrote an entire blog with more details on this phase that you can check out HERE. From a nutritional perspective in this phase, this means, from a day-to-day eating perspective, I recommend a low carb, high fat diet. 

Everybody is different in exactly how much carbohydrate they should be eating in this phase, but it usually falls somewhere between 50g-150g per day. If you’re training volume is generally low (<3 hours per day) and your intensity is also relatively low, you can and should be on the lower end of carbohydrate consumption with a priority on eating lots of good healthy fats (mostly monounsaturated fats like avocados, olives, nuts and seeds) and majority of your carbs coming from high fiber, low starch whole foods. 

This is the perfect time of year to track your blood glucose (refer back to the first blog of the series) and then carb testing (read about that here) as you get ready to approach the start of your season. 

During training, you should consume water and electrolytes only. If you have a hard session or have done strength training, add about 30-50g of carbs in your post workout meal. Outside of that, carbs are low.

Build Training

The build phase of training involves an increase in both volume and intensity with a subsequent increase in your energy requirements (i.e., calories!). 

If you want to read more details on this phase, check out THIS BLOG post. For this reason, from a nutritional perspective, the primary goal is strategic carb cycling. Using the carbs that you tested well to when you carb tested, here is how I generally recommend adding them into the diet:

• For day to day nutrition, remain low carb. For most athletes, the total carbohydrate intake during this time is between 100-150g per day, depending on their activity level.
• For high intensity training (which should be 2-3 sessions each week)- add in about 25-30g of carbohydrates during your training session if it is 90 minutes or longer.  I typically use liquid calories for this like Skratch Hydration mix. If your hard session is shorter than 90 minutes, consider adding in a small amount of carbs pre-workout (if you stomach can tolerate it), like 1/2 banana, and get around 30-50g of whole food carbs in your post workout meal. My favorite go-to post workout meal is a smoothie with coconut milk blended with 1 scoop Equip Prime Protein and 1/2 cooked sweet potato.
  
• For endurance training- add in about 25-30g of carbohydrates per hour of training that lasts longer than 2+ hours. If your training session is shorter than 2 hours, prioritize water and electrolytes only. Then, in the meal following your endurance session, consider adding in 25-35g of carbohydrate to help with recovery. This is especially important if you have another session less than 24 hours away.
  
  

Event Specific Training

In event specific training, we are typically prioritizing event specific efforts. This is usually the phase of training when athletes are doing 2-a-day training sessions and carbohydrates can get up closer to 200g per day for some athletes. 

Like in other phases, most athletes find that they recover faster when they consume the bulk of their carbohydrates after their harder session of the day. 

Since most athletes are not doing 2 hard sessions per day, this means that you would likely only have 1 higher carbohydrate real food meal per day. I usually recommend prioritizing that meal right after your hard session.

During this entire block of training, you can and should test race specific nutrition for a few of your longer sessions that have race pace work in them. This ensures that your body can tolerate your race day fueling strategy.

Since the body can tolerate up to 60g of carbohydrate per hour, you can and should test how many carbs your gut can tolerate during a long session. I typically recommend picking a few endurance workouts in this block to use as nutrition testing sessions. 

Start these sessions fasted (if possible) and start consuming your nutrition within the first 2 hours. Prioritize water and electrolytes until then. 

At the 2 hour mark, slow drip in your planned race fuel, which should be mostly carbohydrate with little protein and even less fat and fiber. If your race is longer than 4 hours, you might try eating some whole food carbohydrates like cooked potato, bananas, or whole food bars. If your race is less than 4 hours, try using liquid calories, like Skratch, or whole food gels, like Huma or Spring gels. 

The amount of carbohydrates to consume each hour is very specific to you, so testing is critical. 

Start with 30g per hour and increase the amount you eat each week. Pay attention to your gut and your energy levels. If you can tolerate 60g of carb per hour without getting any gut discomfort, GREAT! 

If not, how many grams can you tolerate before starting to feel discomfort in your belly? If you have trained your body to burn fat and you can maintain your race pace at a relatively low % of your VO2 max, you may not need to consume as much carbohydrate as you think.

Recovery/Off-Season

In your recovery phase or off-season, getting recovered is the priority. That usually means a decrease in both volume and intensity during training. Hopefully, this also means you switch up your sport for something that supports the goals of your specific sport, but AREN’T your specific sport. For example, if you’re an endurance runner or triathlete, you spend your off-season mountain biking or cross country skiing. 

From a nutrition perspective, since volume is decreased, carbohydrates can also be reduced in this phase of training. For day-to-day eating, I highly recommend doing a 2 week phase of eating very low carbohydrates. For many, this is usually around 35-65g per day and will result in the production of ketone production. 

Once this reset is complete, moving back to a low carb day-to-day diet of anywhere from 50-150g of carbs per day can be done. Most training in this phase is less than 2 hours and water and electrolytes should be prioritized over carbohydrates.

It can not be understated how critical it is for athletes to play around with these recommendations! Every single athlete is so unique in what their body needs. These are merely a recommendation of a jumping off point. But the absolute best thing you can do for yourself is TEST, TEST, TEST!!!


And since my hope is that every single athlete who is reading this is interested in long term health, ensuring that your diet fuels your athletic goals while making sure you are not doing long term damage to your health should be a top priority! 

If you’ve gone through the process of becoming fat adapted and are staying focused on what your carb intake is in relation to your activity level, but you’re still experiencing high blood glucose levels, then check back in next week where I dive into WHY you may still be experiencing those issues!