David: I had constant problems with acne, leaky gut, and digestive upset. I read The Microbiome Solution a year ago, reduced meat to once a month, eliminated sugar and grains, and my meals now consist of a wide variety of vegetables, legumes, wild plants, fruits, and seeds, although most of what I consume is vegetables and fruits. My digestion has stabilized and my acne is gone! I feel great and rested like never before. However, when I exercise, after about 30 minutes I run out of energy and feel weak and tired. Yet, the next morning when I get out of bed there are no signs of fatigue whatsoever. Any advice on why I feel so fatigued when I exercise and how to fix it?
Dr. Chutkan: David, when we completely eliminate grains from the diet, we are depriving our bodies (and microbes!) of complex carbohydrates that can be an important energy source for some of us. I would recommend reintroducing some high-quality gluten free grains like millet, brown rice, buckwheat, quinoa, rolled oats, and teff. These grains are nutrient-dense and can be an important dietary component, especially when considering energy levels during exercise. You may also think about increasing the number of legumes you’re eating. Focus on consuming grains and legumes when you know you’ll need the energy – in the first half of your day, or within an hour or two of exercising. But centering your diet around vegetables, as you’re already doing, is spot on. Utilize grains and legumes as side items to compliment your meals.
Unrelated to your diet, but equally as important, you might consider assessing your sleep quality and quantity, as well as your water intake. Lack of sleep in duration or quality can lead to fatigue throughout your day and especially during exercise, as can dehydration.
Lastly, I recommend assessing your levels of micronutrients associated with energy to make sure you’re consuming adequate amounts. The first two micronutrients that come to mind in your case are vitamin B12 and iron. As reported in our article, Plant-Based Diet: Risks & Benefits, B12 and iron deficiencies are the most commonly observed micronutrient deficiencies in plant-based eaters.
B12 plays an integral role in energy production. While there is no proof that taking a shot of vitamin B12 will immediately boost your energy, there is proof that low levels are associated with fatigue. Low iron levels can lead to anemia, and can also cause the fatigue you’re describing. While a vegan diet can promote lifelong health, paying close attention to your micronutrient levels, especially in the cases of iron and vitamin B12, can be an important step when adopting a plant-based diet.
Vegan sources high in B12 and iron include nutritional yeast and tempeh, and spinach and legumes, respectively. Also, it already sounds like you are, but for others reading, be sure to consume a whole food plant-based diet – meaning one that’s centered on fresh vegetables that will increase micronutrient status – as opposed to a diet comprised of low nutrient, packaged plant-based foods. And finally, it may be a good idea to check in with your doctor and make sure that your oxygen levels during exercise are in the normal range, so you can cross that off the list of potential reasons you’re feeling fatigued during workouts.