Most likely you have heard of CrossFit before. You may
have driven by one of the 13,000 gyms worldwide or have been on the receiving
end of an “I LOVE CROSSFIT” monologue.
CrossFit prides itself not only in building incredible
all-terrain athletes, but also in promoting health and dissipating disease. I
have been a proud Crossfitter for a year-and-a-half and this past summer I
decided to go a little further into the rabbit hole and get my “Level 1
Coaching” certification. This is a weekend certification course that requires
participants to familiarize themselves with a 250-page manual beforehand, and
proceed to spending a weekend with expert coaches practicing technique, cues,
programing, scaling and *cue drumroll*
nutrition.
The overarching dogma for CrossFit nutrition is “Eat
meat and vegetables, nuts and seeds, some fruit, little starch, and no sugar”.
This philosophy, although missing in dairy and legumes, is promoted as ideal for
disease-prevention and for optimizing physical performance.
The diet and nutrition portion began with the trainer
giving a brief and oversimplified summary in the bioenergetics of exercise. I
was very pleased that the off-times outspoken and overconfident grad student in
me simply sat on her hands and did not add “yes, that’s true, but…” after every
sentence. He then moved on to explain the “Zone Diet”, the endorsed diet for
Crossfitters worldwide. This eating plan is designed around a “block” pattern,
where all meals and snacks are consumed in macronutrient blocks of 9 grams of carbohydrates, 7 grams of
protein and 1.5 grams of fat. The numbers of blocks allowed per day/meal
are determined by your protein needs, calculated by your lean body mass and
activity level (reference table below).
So, you wanted to only have grapes for your afternoon
snack? Nope, can’t do that! You will need to add meat, nuts, or oils in order
to stick to your prescribed block pattern. Bon appétit!
I’m sure by now all RDs and RDs-To-Be are cringing in
unison knowing that this massive fitness organization is prescribing ONE diet
plan for ALL participants.
However, I have to confess that I was legitimately
excited during the session in thinking that MAYBE this could actually be a good
recommendation because, let’s face it, CrossFit athletes are just THAT AWESOME
and SUPER-HUMAN. So there I was, drinking the Kool-Aid and nodding along …
while the very far back of my brain was incessantly flipping through all the
evidence-based recommendations for carbohydrate intake in strength and power
athletes.
The weekend ended with strict instructions to give the
diet a two-week chance and “reap the benefits!” So I did. I bought a food
scale, all the fancy tupperwares, and studied the portion sizes and recipes. It
was fun and exciting for about 3.5 days. I did feel like I was eating enough of
food and I liked the menu I had created. However, have YOU ever tried to get
your recommended carbohydrates from just vegetables? It was literally Field Day
for my microbiota. They were happily feasting in all the surplus fiber… and I
was left feeling bloated, gassy, and uncomfortable for the majority of the
day. My food choices and portions also
felt a little strange. I was used to eating beans, peas, grains and nuts, and
it was difficult to incorporate or make them fit the “block” pattern. Although
nuts are allowed in the diet, it was very restricted. The fat “block” in my
snacks was limited to three almonds. T-H-R-E-E. I usually munch on a good 12-18
in one sitting... Talk about needing to adjust portion sizes.
Halfway through my diet endeavor, I decided to comb
through the 250-page manual, looking for any scientific evidence in support of it.
The manual stated, “CrossFit’s best performers are Zone eaters. When our second tier
athletes commit to strict adherence to the Zone parameters, they generally
become top-tier performers quickly. It seems that the Zone Diet accelerates and
amplifies the effects of the CrossFit regimen.” That’s it, that’s all
they gave me… and I found this “evidence” to be, well, wanting.
Taking a
deeper look at the diet, I learned that it was created over 30 years ago
(before CrossFit, Inc.)
by a biochemist named Dr. Sears. He devised this
low-carbohydrate diet claiming that it would improve body composition, reduce
hunger between meals, reduce the risk of chronic disease, and improve athletic
performance in as little as 7-10 days. In my years of experience with nutrition
and exercise, I could understand how the Zone diet could help individuals lose
weight and improve body composition… but I had a difficult time seeing how it
could enhance athletic performance (because leanness does NOT equal better sport
performance). Putting the uncomfortable bloating aside, to me it looked like
this diet was simply too low in carbs and calories for fueling and recovery!
I was able to find one research study that looked at
the Zone diet recommendations and physical performance (Jarvis, et al., 2002).
This study examined the effects of a 7-day Zone diet intervention on maximal
oxygen uptake (VO2max), running time to exhaustion, and body
composition. The study concluded, “… the claim of the authors of the Zone diet
that performance time and VO2 max can be improved was not shown in
this 1-week research trial. We would suggest that this is not a nutritional
strategy that athletes should use until further work has been conducted.”
It is important to note that this study was only one week long, limited to only
eight men in their twenties and looked at parameters that would most likely not
be significantly affected in one week of training. However, this still proves my point. Where is
the research? Why does CrossFit, Inc. feel so strongly about promoting the Zone
Diet?
Keeping in mind the
CrossFit training modality, where intensity is prioritized and workouts are
designed to leave you on your back, in a pool of sweat, gasping for air… I
think there may be a slight disconnect between the diet recommendation and the
workout regiment. These repeated sessions of intense training, followed by
inadequate recovery, have the potential of leading to depleted glycogen stores,
overtraining and central fatigue.
As for me, I was only able
to stick to the Zone Diet for a week and a half. In that time I felt no
stronger, better, or faster than before.
Despite this small scuff in the road, CrossFit and I have a long and
exciting future ahead. I will simply stick to making my own meal plans from now
on. Thanks, but no thanks.
CrossFit diet recommendations (2004)
