I'm helping a group at work do a Biggest Loser challenge, in part by writing a 1-2 page weekly newsletter. In my next issue (next Friday), I'm starting to deconstruct the Calories In vs. Calorie Out (CICO) model for weight loss, and was wondering what kinds of aspects I may be missing. Here's some ideas I have so far, would appreciate any feedback (including criticisms I could encounter)--keeping in mind that my audience at work aren't all low-carbers.

1.) CICO is based on rough analogy of human metabolism to a bomb calorimeter. A bomb calorimeter measures how much energy (measured in terms of calories) it takes to literally burn a food item to ashes. In this context, a gram of fat requires about 9 calories to burn; a gram of protein and carbohydrate each require about 4 calories to burn. However, it is well known that certain components of food, like fiber, cholesterol, the Nitrogen in protein, and some vitamins among others, aren't completely digested by the human body. So instead of a pound (453.5 grams in a pound) of fat requiring 4,081.5 calories (453.5 * 9) to burn, we're told it takes 3,500, which fits conveniently with our 7-day weeks. It's largely assumed that human metabolism is slightly less efficient than a bomb calorimeter in a physics lab. Source: Marion Nestle's "What to Eat" (not a pro-low-carb book/author). From here, the analogies break down even further.

2.) CICO assumes that both the "Calories In" and "Calories Out" parts of the equation are independent variables to one another, ignoring a biological process called homeostasis--our evolutionary tendency to maintain resource levels. Part of why the "Eat Less, Exercise More" idea doesn't always work long-term is that vigorous exercise tends to increase hunger--if you've ever "worked up an appetite," you'll know what I mean. Also, when you progressively restrict food intake long-term, your body adapts by slowing down your metabolism, increasing appetite, and decreasing energy levels--our body's hardwired preservation response to times of famine. Unfortunately, it's like our genes do not understand that we have food available 24/7. Source: Gary Taubes is a good one here, in particular his more readable "Why We Get Fat."

3.) Perhaps most importantly, CICO greatly minimizes the importance and complexity of what a food is actually composed of and how our body's biochemistry interacts with it. CICO is the nutritional equivalent of "judging a book by its cover." For example, in terms of sating one's appetite, protein followed by saturated fat are more effective than non-fiber carbohydrates. Sugar, starch, and even artificial sweeteners and MSG can actually increase one's appetite.

Any advice or constructive criticism would be greatly appreciated. Thanks in advance!