Written by Bryan
To preface this blog post, the idea to run a “sugar free” experiment started about 6 months ago when I went “sugar free” for a short period of time. I almost got over the withdrawal phase, but after 3-4 weeks “sugar free”, I took a trip to Italy that included 7 servings of Tiramisu each night. When in Rome…
Fast forward 6 months and we’ve continued to talk a lot about sugar, both how and why you should avoid it and how to use it. Sugar is still widely viewed as an “essential” ingredient for endurance athletes, and we think it's over used by most people.
This is what we’re going test: can endurance athletes who 10-15+ hours per week benefit from a zero added sugar and low carbohydrate diet?
If an athlete trains 10-15+ hours per week on a low sugar / low carb diet, could they also see an increase in the percentage of fat burned during exercise, without a negative overall performance impact from these dietary changes?
- We’re not going so far into a sugar free or low carb diet that we can’t eat natural sugars like fruit or honey. Ultimately this might make the results less interesting, but we want to make a significant dietary change that still allows us to train, race and exercise like we normally do.
- Additionally, it's important to point out that a lot of research has gone into this topic. We’re not building this test as a scientific study, we're building it so that you can learn from what we learn, and potentially find the right time to try it out for yourself.
- We're also going to end up with a lot anecdotal evidence about how this experience has gone for two of us, but it's critical that you don't immediately apply our experience to your diet and training.
- Two feed staff members, Michael and I, will be eliminating added sugar and drastically reducing carbohydrate intake for 90 days.
- We’ve set this up so that it is repeatable and does not require a huge sacrifice on behalf of the athletes. This might make the outcome less interesting, but we’re going to do this without disrupting our lives and training if possible.
- During this time we’ll be sticking to our regular training schedules and work hours.
- We’ll test our blood work, VO2 max, and body composition before and after 90 days.
- Our blood tests and VO2 max tests will be analyzed before and after by Dr. Kevin Sprouse of Provision Sports Medicine in Knoxville, Tennessee and by Fascat Coaching in Boulder, Colorado.
About the experiment:
Michael and I will be subjecting ourselves to a sugar free and low carbohydrate diet for 90 days. What does sugar free and low carbohydrate mean exactly? We’re going to remain on our normal training plans while completely eliminating added sugar of any kind. We will not be eliminating fruit or natural sugars from maple syrup or honey. We will be mostly eliminating grains from our diets. Think “paleo diet with a lot of privileges”.
We also acknowledge that 90 days may not be a long enough period to see real results, so we will extend that period of time as needed. Additionally, while we encourage you to try this out for yourself, we don't encourage going to extremes and say...completely eliminating carbs. Will one of us eat one piece of cake or a cookie in the next 90 days? Probably. Will we eat one pasta dinner? Probably. The key here is that we’re committed to making a significant change from what our normal diet is.
To quantify changes in diet and performance, we’re partnering with Dr. Kevin Sprouse of Provision Sports Medicine and also with Frank and Carson of Fascat Coaching for physiological testing here in Boulder, Colorado. We’re going to do two identical rounds of testing, with baseline tests during the week of February 16th, and again during the week of May 16th. One test is a blood panel that will assess fasting glucose levels, fasting insulin levels, Hemoglobin A1c (average glucose levels), and a cholesterol panel. The other tests will be a body composition test and VO2 max test from Fascat Coaching. In the VO2 max test we’re looking to see specifically what happens to the % of carbohydrate burned vs % fat burned at a given intensity. This measurement will then show us how we’re using fuel at a given output, which can in turn help us tailor nutrition and training to our strengths or weaknesses depending on what time of year it is.
Dr. Kevin Sprouse writes, “The panel of blood work that will be used is a simple and common set of tests that are available at any lab or doctor’s office. The specific values listed above are all impacted by diet, and they all play a very real role in a person’s health. Sugar intake is a major determinant of someone’s blood sugar levels, their insulin production, and even their cholesterol numbers (specifically triglycerides, which are not something you want floating around your bloodstream in excess). Some tolerate sugar wonderfully and suffer no ill health effects. More often than not, though, even very active people consume an amount of sugar that causes worrisome changes in their blood values. Cutting sugar from the diet can improve these things.”
Carson Christen of Fascat Coaching writes, “Vo2Max testing is a great way to determine and understand the metabolic processes of our bodies and determine our metabolic economy (ability to utilize energy). The test data tells us our Respiratory Exchange Ratio (RER) and Respiratory Quotient. The RER is the rate at which our bodies exchange oxygen (O2) and carbon-dioxide (CO2) in and out of the body. The RQ is the rate at which our body burns carbohydrate (CHO) and fat. With this information, subjects can determine how efficiently they burn carbohydrate or fat as a primary fuel source in a resting or active state. Cutting sugar of a diet can alter the bodies “choice” of fuel. The goal of this test and experiment would be to see a shift in the utilization of CHO to fat as an energy source over the course of 90 days or beyond.”
About the athletes:
Michael is a competitive half marathoner and super fast runner in general. He just finished 3rd overall at the Austin Half Marathon with a time of 1:09:38. That’s really fast for anyone, much less a guy with a full time job! If you order from The Feed, chances are Michael packed and signed your box. During the spring, Michael still wants to stick to his weekly training plan and get faster, so it’ll be interesting to see if his performance suffers or improves.
As for myself, I’m a cyclist, skier, runner, nordic skier and crossfitter. I do whatever physical activity I have time for on a given day, and don’t have a structured “training” program. During this period, I’m hoping to get a better idea of what my overall weekly training volume is, and whether my performance can increase on a low sugar diet.
Throughout the 90 days, we will be keeping track of our overall training volume and activities with TrainingPeaks. This will be especially important for my training as I do a lot of different sports and don’t have a structured training program.
If you are an elite level endurance athlete who trains 20+ hours per week, repeating this test only makes sense during the off season, or when you are far away from key events. At 20+ hours per week of training, carbohydrate intake just needs to be higher than it does for the rest of us.
For the rest of us, athletes who train through the work week with eye on competing over the weekend, we think this test will yield hugely positive results for a lot of people. We’ve heard it all recently: “this one guy wins marathons on a super high carbohydrate diet, eliminating carbs and sugar is stupid”. “That isn’t a significant dietary change” or “high intensity will be impossible and will feel terrible” or “your fitness will suffer”. Perhaps all of that will be true, but we don’t think so, and we hope to find out for ourselves.
Over the course of 90 days, we believe that our performance and overall health will generally benefit from a reduction in sugar and carbs. I think we will see a small improvement in VO2 max, a significant change in body composition (leaner, less body fat), as well as an improvement in our blood work. Most importantly for me, I think I will see an increase in the percentage of fat that is burned for fuel during exercise. I do think that Michael and I will have a tough time in the first 3-4 weeks. With a severe reduction in sugar, we’re going to go through withdrawal and our performance will suffer early on as a consequence. I think this will change after 5-6 weeks in and at that point we’ll be ready benefit dramatically.
We hope you enjoy following along to see what Michael and I experience, and we’ll work on writing regular updates to let everyone know how things are going. If you have any questions that you’d like us to address as we start the experiment, please add them in the comments below, or email me directly - firstname.lastname@example.org