Long endurance fueling from fats

For long endurance rides, as I understand, a significant amount of your bodies fuel typically comes from fat sources, and less from carbs. What are some suggestions for fat fuel sources while riding? OR, is your body using fat from your body as fuel and no need to eat fats while riding and just eat some carbs, but not nearly as much as you would if you were going high intensity riding.
thanks a bunch!
(And as a follow up from the comment in the last podcast: yes my last name is really Livengood, but it is pronounced with a long “i”


As far as I know your body is very clever and as such will take the availability of recently consumed fuel over that of long term fat stores. I guess that is why fasted rides carry such a stigma, you are not fuelling and so force the body to use stores. Honestly I have so much doubt over fasted rides but that’s another post for another day.
Personally I would just fuel the ride as you normally would and not overly worry about the macro breakdown.

I’m not an expert in this area but fro what I understand; your body will use stored fat as a fuel source when glycogen has been depleted. While riding above certain intsities, you are not able to intake enough calories to offset the calories spent while cycling. On a long enough timeline, your body will run out of glycogen because you just can’t eat enough and begin using stored fat as a primary fuel source.

Depending on how good you are at eating, how efficient your body is at using the calories you eat and how great your body’s glycogen stores are, this could occur in a couple hours or it could happen eight hours int the ride.

Other factors to consider are how efficient your body is at using stored fat as fuel. People who regularly train in a fasted state may be better at using stored fat. Regardless of how good your body is at using fat as ride fuel, it tends to not be great at higher intensity efforts, about 70% of normal performance from what I’ve read so again, not bad for super long distance stuff where intensity is less of an issue.

All that being said, I would avoid eating high quantities of fat while riding. Fats are the slowest digesting macro-nutrient and may slow down your gut’s ability to process carbohydrates which are a far more important fuel. Fats can also increase the chance of upset stomach and other digestive problems while riding. Carbs best, protein second and fats are least desirable.

In the end, Cals are good and I have no problem smashing a burrito 6 hours into a 200k ride though!!!

Take everything I’ve said with a grain of salt, I am not a nutrition or diet expert and I’m probablty dead wrong on at least one thing here.

Also not an expert but have a few thoughts. Exercise intensity is going to be the strongest dictating factor as to what fuel source is burned. You can be super glycogen loaded at the start of a ride but if you’re only going at 50% max the predominate fuel source is going to be fat (see image) which by the way even the leanest athletes are going to have tens of thousands of calories on board in the form of body fat so as you guessed no need to seek out large amounts of additional fat other than what will be naturally occurring in the typical foods we eat on the bike.

Carbohydrates are still going to be your performance limiting fuel source since we can only store around 2000 kcal worth in the form of muscle glycogen and likely only have access to a portion of that.



Hi Jon,

There’s no reason to fuel with fat during exercise. Even the leanest athlete stores enough fat to fuel exercise for much longer than you’ll ever need. And eating too much fat during exercise can slow digestion or cause stomach problems.

While your body does indeed use more fat as fuel at low intensities, you’ll still use plenty of stored muscle glycogen. So while it’s true that during short+easy rides you don’t need to take in too much carbohydrate, during long rides you probably should, even if they’re at low intensity.

By the way, I really can’t recommend reading this article enough: