“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 firstname.lastname@example.org or leave comments below. UP, UP, and AWAY!! WHOOSH!
[pic from hamed]