“Eat meat, vegetables, nuts, and seeds, some fruit, little starch, no sugar.” That’s the basic Crossfit prescription for nutrition, but I’m going elaborate on why we eat that way. Our diets prioritize health and performance, so, in addition to satisfying basic nutritional needs, we want to maintain lean body mass and improve our recovery times by controlling inflammation.
First we have to consider the macronutrients: Protein, Carbohydrates and Fat. Protein provides essential amino acids and having enough of it maintains or increases our lean body mass. Plant proteins, such as those in grains and legumes, are not as easily absorbed, so animal products (meat, eggs, dairy, seafood) are our best source for protein. Carbohydrates, which include fruit, vegetables, grains, sugars, and starchy roots and tubers, are broken down into glucose to be used for energy. Carbohydrates are not essential in our diets, as the liver can produce glucose when carbohydrate stores are low. Fat provides essential fatty acids and, at 9 calories per gram, is the densest source of energy at our disposal. There are three types of fat, polyunsaturated, monounsaturated, and saturated. In future write-ups we’ll talk more about fat and dietary fatty acids. For now I’ll simply recommend getting your fats from a mix of animal products, nuts and seeds, and the less refined vegetable oils, such as olive oil and coconut oil.
We also want to consider the micronutrient content of our food, that is, vitamins and minerals. Animal products are our best source for the fat-soluble vitamins A, D, E, and K as well as the B complex vitamins. Fruits and vegetables are the most dense sources of vitamins and minerals per calorie versus grains and starchy roots. Sugars have little or no micronutrient content.
Our last big consideration is how these macro and micro nutrients affect body composition. To reduce excess body mass and maintain lean mass, we need to take control of our insulin production. Consumed carbohydrates break down into glucose and are sent into the bloodstream where insulin “pushes” the glucose into our muscles and organs. From there, glucose is used as energy or stored as glycogen. High insulin levels also signal our bodies to stop using fat as an energy source. By keeping our insulin levels fairly low, we can improve our utilization of fat. The glycemic index of a food refers to how quickly that food is digested and releases glucose into the bloodstream. Sugars and refined carbohydrates such as flour and cornstarch have a high glycemic index, and thus our body must release more insulin to control blood sugar levels after ingesting these foods. Grains and starchy roots have a lower glycemic index than refined carbohydrates, but they still produce higher blood glucose levels (requiring more insulin) than fruits and vegetables. Eating protein produces the hormone glucagon, which acts in opposition to insulin, while fat is more or less neutral on the insulin/glucagon scale.
Our goal as athletes is to increase our performance and improve our health. Now that we have the very basics of macro and micro nutrients down we can start to formulate a basic diet plan. We need to provide protein for essential amino acids and to maintain lean muscle mass and we need fat for essential fatty acids. We’d like to get the best micronutrient bang for our…calorie?…so we add on some fruits and vegetables. Now we just need a nice dense energy source to round things out, fat or carbs? If we choose carbs for our energy source we’re either stuck eating monumental amounts of fruits and veggies or a fair amount of whole grains (lets cut out sugars and refined stuff all together). On the other hand, if we choose fat (from animals, nuts, and seeds) we can keep our insulin levels low to burn off our own extra stores and reduce some of that intimidating volume of veggies (a cup of cooked broccoli is only about 50 cals).
So what does it all come down to? Eat meat, vegetables, nuts, and seeds, some fruit, little starch, no sugar. Oh. Cool.
Next time we’ll go over some strategies like quantity control (Zone Diet) and quality control (Paleo Diet). Send your questions and comments to ben@crossfitcharlottesville.com or leave comments below. UP, UP, and AWAY!! WHOOSH!
[pic from hamed]
Here’s an interesting article about high vs low-fat diets in rats. The little guys didn’t seem to do so well on high-fat kibble, in terms of performance in a maze and on a (tiny) treadmill.
http://well.blogs.nytimes.com/2009/08/13/fatty-foods-affect-memory-and-exercise/
and the original article can be downloaded from:
http://www.fasebj.org/cgi/content/abstract/fj.09-139691v1
Not sure how easy it is to translate rat diets into human world, but food for thought. 55% fat seems like a *lot*, regardless, and perhaps it was the change from a high-carb (75%) to exceedingly low-carb (16%) food that did them in. It would have been nice to vary ratios of all 3 nutrients (carbs, protein and fats) to see what the important piece really was.
The comments below the nytimes post (and rejoinders from the author) are highly entertaining. There are some good points about the duration of the study (perhaps too short) and bad points about animals (fat is ok because elephants are fat and have good memories – brilliant!).
Ben,
I would have started this by talking about evolution. Thinking about how evolution has affected humans, it seems obvious to me that there has not been enough time for humans to have evolved to eat neolithic food without problems. Neolithic food is stuff humans have eaten for less than 10,000 years like grains, legumes and dairy. (It is obvious that humans aren’t adapted to eat large quantities of sugar, but this goes way beyond sugar.) Individual humans may have PARTIAL adaptations to a neolithic diet, but not perfect adaptation.
When humans first started eating neolithic foods, there was selection for genes which could better process these new foods. For example, the lactose gene unlocks more calories in milk. Evolution does not drive toward perfection, but only selects for something which is better (even if only by a little) than before.
The neolithic diet may be suboptimal. Humans likely switched food sources because of overhunting. From wikipedia: “The Hunting hypothesis suggests that humans hunted megaherbivores to extinction. As a result, carnivores and scavengers that depended upon those animals became extinct from lack of prey. Therefore this theory holds Pleistocene humans responsible for the megafaunal extinction. One variant, often referred to as overkill, portrays humans as hunting the megafauna to extinction within a relatively short period of time. Some of the direct evidence for this includes: fossils of megafauna found in conjunction with human remains, embedded arrows and tool cut marks found in megafaunal bones, and cave paintings that depict such hunting.”
source: http://en.wikipedia.org/wiki/Quaternary_extinction_event#Hunting_hypothesis
Plants have evolved defenses against being eaten. See here:
http://en.wikipedia.org/wiki/Plant_defense_against_herbivory
The 400 generations since humans started relying on plants for a substantial portion of their calories isn’t enough time evolutionarily speaking for humans to evolve defenses against plant toxins. Food allergies are fairly common. These are acute reactions. Chronic reactions probably are widespread, but people don’t make the connection to their health and what they eat specifically.
Nice article, Ben! Now I want a detailed explanation on eicosanoids and their relationship to the lactate shuttle.
I believe in more fish than meat and think that research supports this…
From a health perspective, I think you can get just as much, if not more, quality out of meat than fish, so long as you’re buying from good producers. At the same time, because of the generally awful conditions of fishing stocks worldwide, I think overall cost/benefit greatly favors consumption of land animals.
@Neolithic eater: Definitely liked the elephant comment the most. I would check out these articles from Stephan at Whole Health Source (great blog): http://wholehealthsource.blogspot.com/2009/05/eicosanoids-fatty-liver-and-insulin.html (there is a note at the bottom about how rats feed on high fat diets) and http://wholehealthsource.blogspot.com/2009/06/letter-to-editor.html I think the main issue with fat consumption is going to be the omega-6/omega-3 ratio. If you crunch the numbers from one of the comments by the author, the high fat diet was getting more than triple the amount of polyunsaturated fats (4.34% vs 13.75% by percent of calories) and mostly omega-6 by the looks. This combined with the difference in how rats eat on a high fat diet might make the difference. Just speculation though!
@Jason: I definitely like attacking things from the evolutionary standpoint as well, but for this article I was shooting for coming to the right conclusions in a really basic way. I’m sure we’ll go over the logic behind paleo nutrition at some point though.
@Bin: I heard eicosanoids were fake and that the lactate shuttle is not the fastest way to the airport. Is this true?
@martha: Again I think the “fish is better than meat” mostly ends up coming down to omega-6 vs. omega-3 fatty acids, which I’m sure we’ll cover in depth in a post soon!
solid post. you guys should add a digg tagger to the blog–
here’s the one thing that I think you have to keep in the back of your head as you work on fine-tuning your nutrition–the human machine is a remarkable mechanism.
sure, we may not be optimally adapted to a neolithic diet, but for millenia, human beings have achieved extraordinary things in terms of physical prowess on a variety of diets (and lack thereof). in the last century, when carbs ruled fueling up for marathons & other endurance events, amazing records have been set, achievements made, etc. our bodies are exceptionally capable when it comes to teasing out nutrients from lackluster sources.
so on the one hand the principles of Zone & Paleo I think can be incredibly useful and effective in pushing plateaus and optimizing performance, on the other, don’t let any nutritional inadequacy in your diet become a mental crutch while you’re training.
Hey there! I’ve been reading your blog for a while now and finally got the bravery to go ahead and give you a shout out from Lubbock Texas! Just wanted to tell you keep up the good job!