The CrossFit Journal article above details the Zone diet and building meals (the 'how"). Below is a description of our nutrition philosophy and our prescription for eating healthy (the "why").
Eat meat and vegetables, nuts and seeds, some fruit, little starch and NO sugar. Keep intake to levels that will support exercise but not body fat.
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.
Glycemic Index vs. Glycemic Load
The Glycemic Index has been well studied by health experts but has recently been popularized by diet gurus like Barry Sears as an integral tool for effective weight loss. Today, it's nearly impossible to find a diet-related book that doesn't give mention of the Glycemic Index. But what doesn't get nearly as much attention is the Glycemic Load of food. While it is equally as important as the Glycemic Index, becoming well acquinted with both is ideal.
What is the Glycemic Index?
The Glycemic Index is a ranking system for carbohydrates based on their effect on blood glucose levels. It was developed in 1982 by scientists to accurately describe how quickly a carbohydrate converts to sugar and is released into the blood stream. Food is rated on a scale of 0-100, with pure sugar topping the charts as the highest GI food.
How does it work?
ALL carbohydrates turn into some form of sugar (glucose) in your body. When you eat food containing carbohydrates, the carbohydrates are broken down into sugar (glucose) during digestion and then released into your bloodstream. As your blood glucose rises, your pancreas secretes insulin to help shuttle the glucose out of the blood and into the cells. This increase in insulin production and blood glucose is often described as a "sugar rush" or "spike". The speed at which your food increases your blood glucose level is referred to as the "glycemic response". Choosing food with a low Glycemic Index (<55) will produce a minor fluctuation of blood glucose levels. Often times after eating a high GI food (>70) you'll experience a short surge of energy followed by an equally powerful crash as your blood sugar plummets. This is a vicious cycle that can lead to weight gain because you'll often reach for more food when the "high" wears off.
Why should you care about Glycemic Index?
Adhering to foods with a low (<55) or medium (56-69) glycemic index will help stabilize blood sugar and keep you from riding the energy roller coaster. Typically, foods with a low GI, like fruit and vegetables, have more fiber which will help keep you full longer between meals. This is why low GI foods are commonly recommended for individuals that are trying to lose weight. More importantly, these foods are more nutritious than their sugary and refined counterparts. When it comes to weight loss, it's best to limit the amounts of the higher GI foods and load up on the low-to-medium GI ones.
What about Glycemic Load?
The glycemic index compares the potential of foods containing the same amount of carbohydrate to raise blood glucose. However, the amount of carbohydrate consumed also affects blood glucose levels and insulin responses. The Glycemic Load of a food is calculated by multiplying the glycemic index by the amount of carbohydrate in grams and dividing the total by 100. The Glycemic Load gives you a more complete picture as it takes into account the quality (glycemic index) as well as the portion size of a carbohydrate in a meal. This means that if eaten in smaller quantities, a high GI food can actually have a low GL and be pretty harmless.
Calculating Glycemic Load
GI is 85 (high)
GL= (34g x 85)/100
The Glycemic Load is 29 This illustrates how the ranking system for GL factors in the portion size as well as the GI to provide a more useful measure of a carbohydrates effect of blood glucose.
Glycemic Index of Vegetables (low-high):
Red Peppers 10
Green peas 48
Corn, fresh 60
Glycemic Index of Fruit (low-high):
Figs, dried 61