Nutrition is the foundation of the health and wellness. It is more important than exercise. We reject the low fat/high carb diet, and embrace lower carb protocols which are aimed primarily at regulating insulin.

"The CrossFit dietary prescription is as follows:
Protein should be lean and varied and account for about 30% of your total caloric load.
Carbohydrates should be predominantly low-glycemic and account for about 40% of your total caloric load.
Fat should be predominantly monounsaturated and account for about 30% of your total caloric load.
Calories should be set at between .7 and 1.0 grams of protein per pound of lean body mass depending on your activity level. The .7 figure is for moderate daily workout loads and the 1.0 figure is for the hardcore athlete.

What Should I Eat?
In plain language, base your diet on garden vegetables, especially greens, lean meats, nuts and seeds, little starch, and no sugar. That's about as simple as we can get. Many have observed that keeping your grocery cart to the perimeter of the grocery store while avoiding the aisles is a great way to protect your health. Food is perishable. The stuff with long shelf life is all suspect. If you follow these simple guidelines you will benefit from nearly all that can be achieved through nutrition.

The Caveman or Paleolithic Model for Nutrition
Modern diets are ill suited for our genetic composition. Evolution has not kept pace with advances in agriculture and food processing resulting in a plague of health problems for modern man. Coronary heart disease, diabetes, cancer, osteoporosis, obesity and psychological dysfunction have all been scientifically linked to a diet too high in refined or processed carbohydrate. Search "Google" for Paleolithic nutrition, or diet. The return is extensive, compelling, and fascinating. The Caveman model is perfectly consistent with the CrossFit prescription.

What Foods Should I Avoid?
Excessive consumption of high-glycemic carbohydrates is the primary culprit in nutritionally caused health problems. High glycemic carbohydrates are those that raise blood sugar too rapidly. They include rice, bread, candy, potato, sweets, sodas, and most processed carbohydrates. Processing can include bleaching, baking, grinding, and refining. Processing of carbohydrates greatly increases their glycemic index, a measure of their propensity to elevate blood sugar.

What is the Problem with High-Glycemic Carbohydrates?
The problem with high-glycemic carbohydrates is that they give an inordinate insulin response. Insulin is an essential hormone for life, yet acute, chronic elevation of insulin leads to hyperinsulinism, which has been positively linked to obesity, elevated cholesterol levels, blood pressure, mood dysfunction and a Pandora's box of disease and disability. Research "hyperinsulinism" on the Internet. There's a gold mine of information pertinent to your health available there. The CrossFit prescription is a low-glycemic diet and consequently severely blunts the insulin response.

Caloric Restriction and Longevity
Current research strongly supports the link between caloric restriction and an increased life expectancy. The incidence of cancers and heart disease sharply decline with a diet that is carefully limited in controlling caloric intake. “Caloric Restriction” is another fruitful area for Internet search. The CrossFit prescription is consistent with this research.  The CrossFit prescription allows a reduced caloric intake and yet still provides ample nutrition for rigorous activity. "

--quoted from crossfit.com

CF Issue #21 has an easy to understand explanation of the Zone. It also provides a block chart for the most popular foods, and many CrossFitters have found it extremely helpful to keep a copy of the chart on the fridge door.

Books on nutrition that we recommend are in the column to the bottom right.

The theoretical basis behind all lower carb/higher fat diets has roots in evolutionary biology. In this view, human beings evolved over some 500,000 years on diets that were very low in carbs compared to modern diets. Human metabolism was preferentially fat burning. The advent of agriculture approximately 10,000 years ago made civilization possible, but it also brought in many new foods that had not previously been part of the human diet. Almost without exception these new foods, mostly grains, were carbohydrates.

The insulin system exists to regulate levels of blood glucose. Carbs, when digested, are broken down into glucose, and as they enter the blood stream the body reacts to elevated glucose levels by secreting insulin. Insulin directs glucose first to the brain and muscles for immediate use, 2nd a very limited amount may go to replenish glycogen stores in the muscles, 3rd it takes any left over from these priorities and stores it as fat. This is one reason why we say it is carbs that make you fat.  If this is hard to wrap your head around consider how farmers fatten cows and pigs-they feed them corn.  Exess carb consumption leads to chronicly high level of insulin, and, in the long term, this causes metabolic havoc, leading to an ever expanding host of illnesses that are being attributed to hyperinsulinsim in current research.  These include obesity, diabetes. high blood pressure, high triglycerides, hypoglycemia, and even cancer, acne, early puberty, erectile disfunction, & infertility. (Try a google search with "hyperinsulinism" and any of these terms)

Have you ever eaten a candy bar and felt energized for a few minutes but then sleepy or hungry within about 30 minutes? Have you binged on chips, candy, etc never feeling satiated for very long? If so, you were on the glucose/insulin roller coaster. You eat a high glycemic food, it gives a rush of glucose and energy. The body responds to the high blood glucose with a spurt of insulin, even an over reaction because of the speed of blood glucose rise. The insulin reduces the blood glucose, making you fatter, hungry and/or sleepy. As a final insult, carbs are addictive. They hit the same pleasure receptors in the brain as other addictive substances like crack or heroin. Your body adapts to high carb diets by burning carbs in preference to body fat in resting mode, making it very difficult to lose fat. When you cut down on carbs you may have withdrawal symptoms as your body goes through the difficult process of returning to its evolutionarily natural state of burning fat preferentially.