This time of year, many clients are gearing up for 10k runs as well as half and full marathons. One of the most common questions I get asked is “what should I eat before or during my runs?” The common dogma that most nutritionists and coaches preach is to consume a higher-carb meal before competition and then fuel aggressively with gels during your run to maintain top performance. Is this really the only option?
Many people cringe at the notion of having to rely on (and carry around) heavily processed gels to fuel their training. They often tell me it doesn’t “feel natural” to have to consume so many sugars, let alone carry them around with them for most of the race. Is it possible to follow a more evolutionary or Paleo approach to fueling endurance training? If so, what effect will this have on your performance and overall health?
These are all great questions. Let’s take a look at what the latest research is telling us.
If you’ve ever followed a designed program to run a 10k or marathon competition, the conversion around nutrition always comes back to one thing… carbohydrates. Determining how much fuel you need before and during your race will influence how many carbs you’ll need to ingest as a fuel source. While this is still sound advice, it does ignore a major goal of most people who run: to improve health and lose weight.
(Related: How to Carb-Cycle for Fat Loss)
Did you know that even if you are between 7-14% body fat, you still have 20,000-30,000 calories of energy in fat stores on your body?(1) The carbohydrate stores in your muscle and liver (e.g. glycogen) total 500g, which translates to only 2,000 calories of energy. Simple math tells us that 20,000 calories is a lot more potential energy than 2,000, so why so much emphasis on carbs for fuel rather that fat?
The reason carbohydrates are classically the preferred fuel source during endurance exercise is that the research tells us that after approximately 60-65% of your maximum heart rate (HR), you switch over from burning fat for fuel to carbohydrates.(2) During a race, you will most certainly run at greater than 65% HR (a light jog), thus the focus on carbs.
However, there is another option, and it may help you lose more weight during training AND improve your performance! What is it?
A novel new study by Dr. Jeff Volek called the FASTER study compares the effects of a low-carb diet versus high-carb diet in ultra-marathon runners (athletes who run for 50-100 kilometers!). This new study is turning heads because it’s shifting the old dogma that you could only burn 1.0g of fat per minute of exercise. (Well, I guess they never evaluated endurance athletes following very high-fat, moderate-protein, and low-carb diets!)
Volek and his team have found in their preliminary results fat burning rates between 1.1-1.8g of fat per minute (shattering the myth that we can only burn 1.0g of fat per minute). These athletes were also able to sustain their capacity to burn fat up to 75-80% of maximum heart rate, something never thought possible as well.(3) These results, which are not completely finalized, are breaking down a lot of myths and re-shaping the conversation about how “best” to fuel endurance athletes.
This is especially important for people trying to lose weight and improve their health. In clinical practice, I frequently see overweight individuals who run marathons and lose very little body fat. When you take a step back, it makes sense that if you provide your body with excessive amounts of carbohydrates, this will no doubt be the preferred fuel source during exercise. Your body will burn very little fat to fuel you during your workouts.
However, if you remove the carbs before training, you can increase your reliance on body fat.
So, what should you eat before training? If you’re trying to lose weight and improve health, simply decrease the amount of carbs you eat before exercise. For breakfast, go with eggs, bacon, and healthy monounsaturated fats like avocado, or saturated fats like butter. Just reduce your intake of breads, juices, and cereals so your body can begin to adapt to burning more fat for fuel.
If you run in the evening, then a lunch made up of a big salad with a generous serving of animal protein (e.g. 1.0-1.5 “palms” worth in size and thickness for females, and 1.5-2.0 “palms for men) topped with olive oil (1-4 tbsp.) would be the perfect way to keep your carbs down, and your protein and fats up.
If you get hungry before the run, try a small handful of walnuts or macadamia nuts to satiate your appetite but still allow you to burn fat for fuel.
Kick Up The Fat-Burning Potential
If you want to ramp things up even further, add some MCTs (medium-chain fats) to your morning coffee, as they provide an instant source of energy for the body. Unlike longer-chain fats, MCTs are metabolized directly from the gut in tissue and can be burned easily for fuel. Think of them like kindling for your metabolic fire, whereas the typically longer-chain fats must first be sent to the liver and processed into smaller morsels before being used for energy. This process won’t allow you to use traditional fats for fuel during exercise as it simply takes too long.
(Related: The Facts About Fats)
How Will I Feel During My Workouts?
The process of transforming your body to become more fat-adapted takes approximately two weeks.(4) Therefore, don’t be surprised if your performance dips in the short-term. You may feel a little more fatigued, or your muscles may get a little more tired during exercise. Your body will adapt, so allow it time to do so. The most common mistake is reverting back to higher-carb meals before the full two-week period has run its course and the body has not yet ramped up its fat-burning potential.
For those who are looking to lose weight and improve their health, this new paradigm shift of fueling with healthy fats has the potential to be a real game changer for promoting better health and body composition. The excessive consumption of sugars via gels and bars for people trying to upgrade their health and wellness really puts the brakes on the health benefits of endurance exercise.
What If I Want To Perform My Best, Is It Still Possible When Fueling With Fats?
This is a tough question to answer at this time. The results of the FASTER study are due out this fall and no doubt will shed some new light on whether this increased capacity to burn fat also translates into better performance, or if the carb group still comes out on top.
In reality, for performance benefits we would only have the endurance athlete fuel with high fat coming out of the gates for the first hour or hour and a half.
After that, adding some rapidly-absorbed amino acids or BCAAs (5-10g) + MCT oil (1-2 tbsp.) + simple carbohydrates from clean gels like Hammer, GU, or Skratch are all good options. It is important to try to avoid added fructose and excessive caffeine in your gels.
Remember, contrary to popular belief, you don’t have to be in a state of ketosis – when your body begins to produce ketone bodies due to the restriction of dietary carbohydrates – to be very efficient at burning significant amounts of body fat.(5) The latest research is showing that low-carb, high-fat diets can provide a tremendous increase in fat-burning capacity as well as possibly supporting better performance. For overall health and better body composition, reducing your intake of simple sugars will also translate to better digestion and immune function, blood sugar balance and fat loss.
Don’t fall victim to common myths around endurance sports nutrition. Try a more Paleo-friendly approach to fueling for your endurance training and discover how you can crank up your fat-burning potential and upgrade your health and performance.
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