Here is the text of Dave's commentary from the CrossFit Radio show on 4/18/2009:

"I have learned many things as a CrossFit coach, among them that teaching people what they cannot do is far more powerful than teaching them what they can do. Put another way, people need to fail to grow.

There is a correlary in diet. Whether we are schooled in Zone or Paleo or some combination of the 2, we tend to fixate on our recommended units of food, in addition to the quality of our food and the macro-nutrient balance. Those of us that are diligent about diet and want to get it right are often the worst about ignoring another valuable diet variable.

Just like with exercise when we focus too much on what we can do - while neglecting to ever determine what we can't do - in diet, we focus on how much food is too much food but we never explore the benefits of knowing how much food is too little. Notice I didn't say we should actually eat too little, I said we should know how much is too little. But it is true that the only way to know that is to actually eat too little for at least a brief period of time.

The process for determining this is a little delicate, but definitely worth the effort.

The important concepts here that may be new to you are:

• you must be in control of everything that you put in your mouth -
  no mindless eating - not knowing how much food is too little is mindless
  

• humans do best (i.e., perform better) with a quantity of food that is just this side of too little

Therefore, in addition to everything you know about diet and how to create a healthy one, add this to the list; continue to force your quantities down to a point that - however briefly - you know that you are eating too little food. You'll know it just like you know everything else about your health; your energy and your performance will begin to suffer. I trust you pay close attention to that. If you don't, here's yet another great reason to do that.

You'll want to repeat that process about once a year. When you do, you'll be surprised at how little food you need, and at how good you feel when you do it."