What is a healthy amount of fat to consume to get me through a 2 hour bike ride and reduce my body fat percentage?

Hello Joshua.

Your question has to do with fuel utilization during exercise. So that you understand where I am coming from think of:

1. Carbs
2. Fats

as fuel sources. For example

The fuel source for gasoline is crude oil or petroleum. The petroleum has to go through refinement before it is gasoline. One can not simply purchase crude oil and pump it into their car.

Same thing with carbs and fats. It needs to go through metabolic processes in order for the body to utilize it.

FYI, the science says that the only time we utilize fats as a fuel sources is when we are sleeping. Once we start moving the percentage of fat utilized for energy drops and the utilization of carbs increases.

So during your 2 hour bike ride you will be using mostly carbohydrates primarily as a fuel source as a consequence of the intensity of your bike ride. It requires more energy than sleep so the ratio of fat to carbs used as a fuel source changes.

Additional information that may be of interest to you:

This is from Practical Applications in Sports Nutrition written by Heather Hedrick Fink, Lisa A. Burgoon and Alan E. Mikesky. It states in response to the following question:

"How are daily fat needs calcualted for endurance athletes?

"For endurance athletes, fat requirements are generally calculated after determining carbohydrate and protein needs. Carbohydrates are the main fuel in the body for endurance sports and protein is critical for repairing muscle tissue after long-duration activities, especially weight-bearing sports. Therefore, both macronutrients take precendence over fat."

Conversely, fat rich foods are calorie-dense, allowing an athlete to consume more calories with less food and without feeling too bloated."

"Endurance athletes, especially those trying to lose weight or body fat--often become too focused on carbohydrates and lean protein sources, while attempting to minimize or eliminate fat intake."

"if carbohydrates needs are calculated at 50-65% of total calories and protein needs fall between 12% and 20%, then the remaiing calories should be contributed by fat--approxmately 20%-35% of total calories. Most often, fat needs for endurance athletes will be calculated at the lower end of this range."

Joshua, don't 't think for one minute that because you are not utilizing fat primarly as the primary fuel source your body is not consuming calories. You are.

I sure hope this answered your question.

Have a great ride!

Michael, what about RER?

I like Joanne's response citing useful percentage ranges for macronutrients. 20-35% of total calories is usually ideal. Only you and your dietician can decide where in this range you should be.

The night before your bike ride you will need a lot of carbs for sure then maybe protein in the morning to keep blood sugar stable. We can't recommend specific amounts because we don't know your age, height or weight, or current body composition.

It is great that you are keeping track of VT1 as this will allow you to get the most total volume in your workouts. Joanne is right, however, that you will mainly be burning fat when you sleep, but also you should be burning fat while you exercise after about 90 minutes in. This is also when you will need to replenish some electrolytes so you don't sweat too much and get dehydrated.

If find you are craving fats, indulge in the good kind: nuts, seeds, natural vegetable oils, fish, coconuts, avocados, dairy products, etc. This way you will burn off the bad fat and have even more energy than before!

My weight is 185 lbs and I have 7% body fat. I a 23 years of age as well. I was assuming that while at VT1 the calorie I am burning are coming still mostly from fat as I have not increased my tidal volume as my body would then switch to consuming more carbohydrates. Timing I am sure is very important and I think If I could get more glycogen stored in my muscles and have more FFAA's then my ability to utilize readily available energy would allow for me to maintain he current body composition I have and maybe reduce it. But to reduce it should I focus more on limiting my carb intake or my fatty acid intake? Thank you for all the educated responses this is very helpful.

How low would you like to see your bf% go? 7% is at least 2% more than your body needs for essential functions. When my body fat got down to 6% I decided it was too low. Now I'm up to 8% and I feel like I have way more energy and my muscles are thanking me.

I did some research on Respiratory Exchange Ratio to help the discussion. It turns out that VT1 is usually somewhere near a .85 ratio of carbon dioxide produced to oxygen consumed. At this level of intensity about half of the fuel used is fat and half is carbs.

The higher the intensity, the lower the percentage of fat burned. However, even though less fat is burned per calorie burned, you could be burning more total fat calories at a higher intensity because of the higher combined fuel utilized. When you are asleep the ratio is probably more like .75 and you will be burning around 85% fat and 15% carbs, but less fat than when you exercise.

It would be much healthier to reduce fat intake but I would not reduce your calories much because you don't have a lot of fat to spare. You will need a lot of carbs the day before and immediately after your ride. Hopefully you can afford a dietician consultation for more specific recommendations and please make sure you are getting enough fat to produce the hormones you need for exercise.