Help! Should You Eat Before You Work Out? A Fasting & Fitness Expert Explains

Photo: @jacoblund

When you’re trying to decide whether or not to eat before a workout, you’ll encounter a host of conflicting information. Some people say yes, eating before a workout can give you more energy, and others say no, it’ll slow you down. Here’s why I tell my clients to practice fasted exercise for the sake of their metabolism and fat-burning potential.

For starters, studies demonstrate that aerobic exercise performed in a fasted state as compared to a non-fasted state increases the reliance on fat—and subsequently reduces the reliance on carbohydrate—as fuel during exercise. In fact, several publications have shown that fasted exercise oxidizes (burns) around 20 to 30 percent more fat than non-fasted. Overall, this makes you less reliant on carbohydrates to fuel.

Using carbohydrates for energy isn’t always the best option.

Being less dependent on carbohydrates for energy is a good thing; you will end up feeling less hungry because your body knows how to tap into fat reserves for energy rather than being dependent on the food you eat. For day-to-day activities like walking, jogging, and cycling, fat can be a much better fuel source. Plus, not craving high-energy foods all day can be a big help when you are trying to lose weight and be healthier. In addition, long-term dependence on carbohydrates can lead to insulin resistance, which is one of the key driving factors in metabolic disease and type 2 diabetes.

I suggest starting your fasted training with less intense aerobic activities, such as walking, jogging, swimming, or cycling. Initially, your workouts will feel a lot harder than usual when you train in a fasted state, but quite quickly your body will become more efficient as your muscles learn to use less glycogen, which means you’re using fatty acids for fuel. Once you get used to it, you could start incorporating fasted strength training into your routine, I particularly enjoy fasted strength training since I find it very difficult to train properly with a full stomach, and my abdominal activation seems to improve with an empty stomach. Starting an intermittent fasting program can teach your body to become fat adapted, meaning your fasted training sessions will become effortless.

It’s important to incorporate non-fasted workouts into your routine, too.

Knowing all this, it’s easy to assume that you should never eat before a workout. That’s not true either! It’s important to mix it up so you aren’t always fasting before you hit the gym, sidewalk, or pool. If you know the workout is going to be more intense and cardiovascular-based, I suggest consuming carbohydrates two to three hours before to help with performance and to prevent low blood sugar, which can cause dizziness and nausea.

In addition, issues can arise with fasted training when combined with very low carb diets. The problem with combining fasted training and low carb diets is that you can decrease the body’s ability to utilize carbohydrates. Ultimately, the goal should be “metabolic flexibility,” that is, to prime the body to use both carbs and fat when it needs to. That’s why it’s important to eat more carbs on training days to help replenish your glycogen stores, which get depleted with high-intensity exercise. But if you aren’t training, you aren’t using up your glycogen stores so you don’t need as many carbs, and therefore, excess carbs are likely to get stored as fat.

Don’t try to do everything at once; slowly incorporate fasted training into your less intense sessions, and be strategic with your carbohydrate intake. You should be eating more carbohydrates on your training days and less on your rest days. Fasted exercise is not a magic pill for weight loss, but it can be an effective tool to implement into your training schedule to improve the efficiency of your body’s ability to use fat for energy. In the long term, this can mean a reduced risk of diabetes, heart disease, and obesity.

Is there anything you can consume before a workout? I like to have a strong green tea or black coffee right before my workout. I use caffeine as a performance enhancer, meaning I am very sensitive to its effects. I don’t generally consume it at any other time.



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