Good or Bad-Training “Low” with Carbohydrates?

A few posts ago I wrote on having a daily diet of higher fat and lower carb. The conclusions from the latest research show that while eating a high fat diet, you are indeed going to oxidize more fat as fuel, but you are also turning off your carb utilization. Plus there was no performance benefit for eating this way. Today I want to elaborate on this subject a little more.

The Debate:

Several years ago I heard of many athletes that were trying to train “low”. Low meaning, low carb fuel sources. I had done a bit of research into it for my own athletes and training, but here I’m diving in a bit deeper. First I want to talk a bit about social media, misperceptions, outdated numbers, and good carbohydrate ranges.

Right now, it’s in vogue to be on a low carb/high fat diet. You’ll see these diets around, but the main one that sticks out right now is Paleo. One of the problems is, is that there are very polarized views on the subject, and it’s been brought into the social media. Once things go into the social media, things really seem to take off. There is one well-known researcher that I used to respect quite a bit, but as my husband likes to say “has jumped the shark.” He’s stopped doing research and started using anecdotal evidence. And there has been a lot of public debate on things like low carb diets, etc. So, today I just want to bring you some data from studies. And while studies are very important, nutrition is an art form (as is coaching), and what works for the majority, won’t work for everyone. There is a lot of trial and error in nutrition. Also, nutrition should be periodized. Meaning:

what you eat during your transition period will be different from your base period, will be different from you peak period.

Paleo can and might have a place in your diet, you just have to look at your training goals and what period you are in.

Old numbers:

  • 70% of your daily diet should come from carbs. This is outdated as it doesn’t take into account the period you are in, what sport you are doing, how intense your training is, etc. Realistically, it could be 40-70%

New numbers:

  • low intensity training/skill based- 3-5g/kg/day
  • moderate intensity- 5-7g/kg/day
  • endurance exercise-1-3hrs/day- 6-10g/kg/day
  • extreme exercise 4-5+ hours/day-8-12g/kg/day

The goal of every athlete should be to replace the carbs that they are burning, so they are set up for a succesful session the next day, or later in the day. I’ll contradict myself just a bit later in this post, as reasearch is ever-changing. However, for the majority of the time, for the majority of athletes, this line is key.

Research: Simonsen did a research study involving rowers over a 4 week period. Once group of rowers were eating a moderate intake of carbs (5g/kg) while the other group was eating 10g/kg, or a higher amount. The high group maintained their power, plus increased their overall power by 8%. The moderate intake carb  group actually wasn’t able to maintain their high intensity exercise and lost power. So, this does a good job at showing, if you aren’t taking in enough carbs to replenish what you are using, your performance could fall.

-Also, another take away from another study with endurance runners was, when training with carbohydrate, this enhances our “guts” ability to provide fuel. So, after training with carbohydrates, the runners had improved their ability to absorb carbohydrates from the gut, thus making more fuel available to the muscles.

Pros and Cons of Low Carb Training:

  1. Pro: You can change your body’s chosen fuel source to fat in as little as 5 days. Con: This wasn’t shown to be beneficial to performance.
  2. Pro: You can spare your body’s glycogen and utilize fat as fuel. Con: once your body is in a fat burning state (aka-fat adapted athletes), you can’t “turn on” carb utilization. So, if you need to pick up the pace say while cycling, like you’re sprinting to the finish, your body can’t use carbs as a fuel source, so you will lack power. You will need the power to push, and you just won’t have it. This is true even if you are taking on carbohydrates during exercise. The one place this might work well is for recreational athletes. Athletes looking for performance gains, will find this not beneficial.
  3. Pro: Training low will increase cell signaling, and that leads to enhanced adaptations and training responses aka-better fat oxidation, glycogen storage and possibly greater endurance. Con: You’ll feel sluggish, terrible, irritable and get less work done.
  4. The last con to low carb training is that if  you aren’t consuming carbs before or during your workout, this can have a negative effect on your immune system. So, if you get sick often, this might not be the way for you to go.

So, there are some benefits to training low. Mainly, we want better fat oxidation, better glycogen storage and better endurance, right? At least I do….So, how do we get these benefits, without either shutting off our carb utilization or having a terrible workout?

  • Use easy exercise sessions/non key sessions
  • Do this in your base training period
  • Use this selectively
  • New research is showing that supplementing with caffeine or a carb mouth rinse might trick your brain into thinking your taking in carbs.

To conclude, there are benefits to training low. You just don’t want to train low when  you have an important session, you’re trying to hit certain numbers, you’re in a high intensity period, etc. I think the best way to go about getting the benefits of training low is:

  • Eat a carb diet based on your sport, the period you’re training in and personal preference
  • A workout or two a week, do your a.m. workout without taking in any carb prior. Just wake up, take some caffeine or a mouth rinse of a carb drink, and get started
  • The workout should be nice and easy. Think a cycle session on your training of 1 hour at 65% FTP.

Remember, our goal as coaches and hopefully your goal as an athlete is to figure out the best and safest way to make you better, healthy and happier hopefully. There is room for lower carb training, but the majority of your diet, and the majority of your training should be of moderate to high carb intake. It might just take a few weeks for your body to get used to absorbing the extra fuel. But once it does, your performance will increase.


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