Soy Protein


Soy Protein


I have recently undertaken a goal to get in shape by cycling. I am suplimenting my nightly rides of 5-10 miles with a diet and counting calories. Recently I have been discussing protein bars and shakes and the topic of “soy” protein came up. Some comrades of mine claim that soy protein is not good for you, and it can lead to a build up of tissue in areas (specifically on a male) where one might not particularly want a build up. Yes, I am talking about man-boobs. So, my questions is this, if I eat a Clif bar every day day before my ride do I need to worry about this? Furthermore, if cycling is my primary (and by primary I mean ONLY) form of exercise, is there a good diet plan I should follow or resource for such information you would recommend?

Kelli’s Answer:

Hi Aaron,

Thanks so much for the question.  Soy protein, in the amount of a Clif bar every other day, or even daily, will not cause man-boobs (or any issues from natural estrogens).  And, overall, I do think Clif bars are a good choice for training nutrition (before, during, or after).  However, there are other good choices as well, and it’s a great idea to mix it up.  Post-ride, for example, is a great time for dairy proteins as they better for maintaining a positive protein balancing and discouraging wasting of our muscles compared to soy.

On the other hand, the issue with too much soy causing man-boobs is not completely fictional.  In our Western Society, we can tend to overdo things (I know, sweeping generalization).  Here’s an example: soy protein has some evidence of being an inexpensive, heart healthy, complete protein.  So, do we leave it at whole-food soybeans, edamame and tofu?  Oh no.  We put soy in everything.  We drink it as milk, eat it as yogurt, add it to energy bars, add it to cereals, put it in convenience foods, and add it to breads.  We make fake hot-dogs, hamburgers, and bacon out of it.  Additionally, many companies use soybeans that are Genetically Modified which brings with it many issues (allergies, antibiotic resistance, infertility, etc).  Clif bars use non-GMO soy.

It’s safe to say we do not eat soy as it has historically been eaten and therein lies our problem.  Small amounts here and there are fine.  If it becomes your main source of protein, take a step back and try to add variety.  Most of the research and case studies that show negative estrogenic effects have been seen in infants fed a diet of soy infant formula.  In this case a very small person is being fed a lot of soy protein per pound of his or her weight.  I have also read case studies of adult males with negative man-boob (and other) effects, and again, soy was the primary protein in the diet from milk to yogurt to meat substitutes.

Bottom line: Don’t let your comrades razz you about Clif Bars every other day, but also don’t let soy become your main or only protein source.

As far as a great, fantastic, sure-fire diet for fat loss and cycling, you want to look to a whole-food plan that promote healthy eating day to day with a slight calorie deficit and controlled amount of carbohydrates.  Then, it should still take care of your training needs before, during, and after rides.  I’d have to say that my ebook (Fuel Right) does a good job of this, and I’ll be happy to send you a copy of it this week.  Many diet plans will work for fat loss, but it is very common for an athlete performance to deteriorate while he or she is following them.  On the other hand, advice for athletes’ training needs often promotes too high consumption of total carbs and processed foods, and sabotages fat loss.  I know, shameless self-promotion.


Please send us your questions for our Expert Sports Nutritionist, Kelli Jennings to “Ask the Sports Nutritionist“. Kelli Jennings is a Registered Dietitian with a passion for healthy eating, wellness, & sports nutrition. For more information go to

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5 Responses to “ Soy Protein ”

  1. Ajax on February 13, 2017 at 6:26 am

    So what’s the name of this great protein bar?

  2. Ajax on February 13, 2017 at 6:26 am

    So what’s the name of this protein bar?

  3. Jamie on June 1, 2012 at 3:47 am

    Soy protein reduces the cholesterol and help to reduce the risk of heart disease.

  4. Anonymous on November 25, 2011 at 1:25 am

    Soy is rich in estrogen, estrogen can make your boobs bigger, many pills also has estrogen. If you are taking medicine and you notice some changes in your boobs, consult your doctors about it. | how to get rid of man boobs | get rid of man boobs | getting rid of man boobs

  5. Issa Nicole on May 12, 2011 at 8:27 pm

    Not to completely diss the Clif bar, but there is another one out there I found that is a much greater compared to Clif or in addition to even. This other bar has a great source of fiber, carbs, and proteine. non GMO, soy and corn free, raw, organic, whole, sprouted and clean food is what it’s made of. No artificial sweeteners, no preservatives. How about consume a bar as this one which has hemp seeds and sprouted grains and nuts or even take the tincture that is hemp seed extract X24? That’s a safe and effective form of the most digestible protein as well as vitamin B etc. etc. I’ve been eating this and noticing a huge difference in my training and weight loss. I bought mine at Hope that helps you and lets you know there are other wonderful options!


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Please send us your questions for our Expert Sports Nutritionist, Kelli Jennings to “Ask the Sports Nutritionist“. Kelli Jennings is a Registered Dietitian with a passion for healthy eating, wellness, & sports nutrition. For more information go to

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