Hello Runner,
Welcome back to your weekly moment of endurance nutrition!
Happy Weekend!
How are you?
I'm doing well.
My week was filled with studying, research, and personal development. I'm still keeping up with my training, but it's already taking a toll on me because of the heat. And the worst part is that this hot weather is just getting started.
One good thing is that I've been sleeping VERY well for quite some time now. I think that since the heat tires me out so much, my body completely relaxes at night. I feel like my “body battery” is charging to 100% every night; in fact, even my Garmin tells me that in the metrics every morning, heheh. Even though we can’t trust these smartwatches 100%, I feel like my recovery has been fantastic.
Today’s topic is “train low.” I’ve wanted to talk about this for a while, but I hadn’t researched it thoroughly enough to comment on it.
I didn’t really understand how this strategy works until I learned more about it in the course I recently started.
For those who don't know or have never heard of it, train low is a nutritional periodization strategy in endurance sports where some training sessions are deliberately performed with low carbohydrate (CHO) availability or reduced muscle glycogen stores.
The idea is not to chronically eat low carbohydrate, but rather to strategically manipulate carbohydrate intake around selected workouts to stimulate greater physiological adaptation.
How Does “Train Low” Work?
Your body normally uses carbohydrates (glycogen) as its main fuel during running, especially during faster or harder efforts.
“Train low” means doing some workouts when your carbohydrate stores are intentionally lower than usual.
This forces your body to adapt and become more efficient at using other fuel sources, especially fat.
Training with low glycogen can increase signaling linked to endurance adaptation, including:
↑ Mitochondrial biogenesis (“building more aerobic engines”)
↑ Fat oxidation
↑ Metabolic flexibility
↑ Glycogen sparing during long events
What Does This Look Like in Real Life?
Doing an easy morning run before breakfast → famous training fasted or only drinking water or black coffee
Running after a low-carb dinner → low tank run
Doing two training sessions close together without fully refueling with carbs
Skipping sports drinks/gels/foods during an easy long run
Training hard in the evening and going to bed without eating anything afterwards
Importantly, this is not necessarily the same as a ketogenic diet or chronic low-carb eating.
The key idea is: some sessions are done with lower carbohydrate availability on purpose
The goal is to train low sometimes and use proper fueling when performance matters.
What are the risks of this strategy?
There are significant risks to consider before adopting this strategy. These are:
Reduced training intensity → this can compromise key workouts
Increased stress hormones → can lead to poor sleep and slow recovery
Immune suppression → chronic glycogen depletion may impair immunity
Relative Energy Deficiency (RED-S)
Reduced adaptations if overused → too much train-low can impair training adaptations by reducing training quality
Who Benefits Most and Who Should Probably Avoid It?
→ Perhaps the best candidates to benefit from this strategy are ultramarathon runners and trail runners.
→ Marathon runners and professional athletes, on the other hand, may have a potential benefit, but the individualization must be very carefully considered and implemented.
→ Now, runners with low energy availability, those undergoing heavy training blocks, and amateurs with poor recovery (underfuel, underrecover, and overtrain) should avoid this strategy.
Does Train Low Improve Performance?
Many studies show improved metabolic adaptations but no significant improvement in time-trial performance.
What does that mean? It means we have strong evidence for metabolic adaptations, but not for improvements in race times.
The best choice for performance (A.K.A.: reduce race time) is ALWAYS a high-carbohydrate diet!
Product of the Week
This week's Product of the Week is the 226ers Isotonic Ice Gel.
I mentioned this product in my Instagram Stories this week.
I’d already tried a mint-flavored gel during a long 18K run in the sweltering heat of Barcelona, and it felt amazing.
There aren’t many mint-flavored gel options here in Europe, and this is one of them.
The great thing is that this isotonic gel already contains the amount of water needed for proper absorption.
It’s worth giving it a try.
If you want to implement the Train Low strategy, let it be:
strategically programmed,
individualized,
limited to selected sessions,
Combined with adequate carbohydrate availability for key workouts.
Never try to do this on your own. Always seek help from a professional sports nutritionist.
Track of the Week 🎧️
This week's Track of the Week is a funk classic that I love. I've always been a big fan of this band, and this song is great to have on a running playlist.
I’ve chosen Can’t Stop by Red Hot Chili Peppers
Any questions or something you would like to share, drop me an email
Wishing you a great weekend and week ahead!
Here’s to health and good runs⚡️
Ana Paula Alonso