Will a Vegan Diet Affect Your Workout?
By Joan Kent, PhD
The last thing I'd want to do is try to push a vegan client toward a meat-based diet. But I do get questions about how a vegan diet affects athletic performance, so that's the topic of this article.
There may not yet be sufficient long-term research for definitive conclusions, but we can still discuss aspects of the subject.
What About Protein for Vegans?
Women and men who work out need well above RDA levels of protein. RDA levels are 0.8 g per kilogram of body weight per day, so perhaps 46 g for women and 56 g for men, average. Athletes' protein needs are higher, ranging from 1.4 g to 1.8 g per kilogram.
Reputable sources in the nutrition field point out that, because vegan protein is less bioavailable than animal protein, we need more of it – about 20-25% more plant protein than animal protein. We also need to be diligent about obtaining it.
Tossing a few garbanzos on your salad will not be enough. It may take several cupsful. The same is true for tofu: a small part of a tofu "cake" won't be enough; you probably need the whole thing.
Because plant protein often contains fairly high levels of carbs, it may be quite filling and make it difficult to get enough protein at a given meal. Instead, spread the protein "dosage" throughout the day.
What About Specific Nutrients in Vegan Diets?
Vegan sources of iron include lentils, soy, quinoa, brown rice, oatmeal, nuts, seeds, Swiss chard, collard greens. But plant iron is less bioavailable than animal sources. Combining them with fermented vegetables, such as sauerkraut, will help to increase iron absorption due to the lactic acid.
Vitamin D is an important nutrient for the absorption of calcium, for building and maintaining strong bones, and for general health. Recent discoveries suggest sunlight exposure doesn't produce adequate vitamin D, so other sources are necessary. Try fortified nondairy milks and fortified orange juice.
B12 is typically found in meat only. B12 is important for endurance athletes because it affects red blood cell production.
Again, the solution probably lies in supplements and B12-fortified foods, such as cereals, nondairy milks, soy "meat" alternatives, nutritional yeast.
What About Hormones and Appetite?
By some reports, vegans tend to get hungry soon after eating.
Also, my clinical experience has shown that vegans can get strong cravings for carbs in general, and extremely intense ones for sugar in particular.
Both of these phenomena may have to do with CCK (cholecystokinin), the primary satiety hormone in the body.
CCK is triggered when protein enters the small intestine. It makes us feel we've had enough food and don't need more. It also turns off the desire for carbs, including sugar.
In a comparison study, casein from milk and pea protein offered the highest satiety. But if the vegan diet provides less protein generally and little or no pea protein, CCK levels may be lower.
As a result, the desire for carbs – including sugar cravings – may become quite high.
And What About Brain Chemistry?
When I was a training coach, and the nutritionist, for a performance athletic program, I made an interesting observation about vegans and indoor rowing.
Vegan rowers had difficulty focusing on the training. It was particularly noticeable on the rowing machines; it's quite easy to see when participants lose focus.
I estimated the duration of focus as 30 seconds (really), and even timed it during a couple of trainings to check my observation. Another coach in the program told me one day about a participant in his group who could focus only – I knew he would say exactly this – "for about 30 seconds." That participant was vegan.
My point is: Whatever you say about athletes and vegan diets, protein, and so on, it's important to take into account not only "body protein", but "brain protein," as well. Lack of focus is often due to the lack of specific brain chemicals – dopamine and norepinephrine – that derive from protein. Most analyses of protein for vegans are concerned with body protein only.
For what it's worth, I convinced one of the vegans in the training program to add animal protein to his diet in a form that would work for him. He was willing to have fish – and the focus problem reversed almost immediately.
Focus is essential during endurance athletic efforts and more, making protein essential, too.
In general, however, I don't try to convince vegans to eat animal products. Instead, I encourage use of vegan protein powders – vegetable protein, hemp protein, brown rice protein, for example. This is an exception to my general rule that food should come from whole food sources. I don't believe kale can supply sufficient brain protein, and protein is very important; hence the powder recommendation.
My conclusion here is that plant-based diets do have a more beneficial impact on the planet, yet a full vegan diet might not always be best for endurance athletes – including triathletes.
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