True, But Irrelevant

"Whether anyone likes to admit it or not, for sheer weight loss, it [macronutrient composition of the diet] probably doesn't. It is the total amount of energy consumed (calories) that matters. And this is not an arguable point. There is this pesky little physical law of the universe that forms the basis of all weight loss and weight gain. The first law of thermodynamics states that energy cannot be created or destroyed but is always conserved. In other words, energy that enters a system will necessarily equal the energy that remains in the system or leaves the system. Food, as far as the body is concerned, is merely a form of energy, and the amount of calories you take in (eat and drink) must equal the amount of calories stored in the body or expended through metabolism. Nowhere in this inalterable equation is the quality of the diet or composition of the diet a consideration, only the math of caloric deficit or surplus. It's old, but the phrase "calories count" is still as viable today as it was when the first diet hucksters tried to cash in on the vain American obsession with skinniness. So, according to the law of energy conservation, if you eat according to the food pyramid and keep the numbers of calories you eat to less than you expend, you can lose weight. If you go low-fat and low-calorie, you can eat and drink nothing but Choco Cap'n Crunch and Coke in appropriate quantities and you can lose weight. If you go low-carbohydrate, you can eat and drink nothing but bacon and diet Coke in appropriate quantities and you can lose weight. If you go low-protein, you probably can't think clearly enough to comprehend this, but, believe me, the same energetic relationships apply."
http://community.crossfit.com/article/physics-physiology-and-food

However, all of what was just written, as regards fat loss from dieting by "humans in the wild", is true, but irrelevant.  Thus, though his intro sound like a condemnation of low carb diets (better described as diets free of excessive carbohydrate), read on:

"The low-fat diet presumes, quite correctly, that since fat is a very  energy-dense macronutrient at nine calories (kilocalories, to be  precise, but we'll just call them calories, per popular use) per gram,  reducing how much fat you eat will reduce your caloric intake  significantly. The average American gets somewhere around 34 percent of  total dietary calories from fats in food. Reducing this intake to 20  percent would be enough of a caloric reduction for someone to lose about  a pound a week-if the calories were not replaced with carbohydrate or  protein. (Though, even replacing them on a gram-for-gram basis would  likely net a weight loss of about a pound every ten days or so, since  both carbohydrate and protein contain 4 calories per gram.) If you can  hang with the food choices of the low-fat diet, you can effectively lose  weight.    For a chance at success with a low-fat diet, not only do you need to  change the foods you eat, you also need to change how you eat. Instead  of three squares a day, it is much more effective to eat four or five  smaller meals with little snacks between. Spreading the food relatively  uniformly across the waking day helps minimize the time between insulin  concentration troughs, thereby helping limit between-meal hunger pangs.  

"It is interesting to note that, in the last decade, the  government-sponsored campaign against dietary fat has resulted in a  decrease in the percent of fat in the American diet (it peaked out at  over 42 percent a few years ago). But, over the same time, the average  bodyweight and body fat of the average citizen has increased despite the  decrease in dietary fat. Oops.    

"How is this true for carb restricted diets?  The highly touted low-carbohydrate diet has some quite clever elements  that are biologically effective and promotionally effective. "Eat as  much protein and fat as you like" is one element that almost every one  of its practitioners loves. "Wait, I'm on a diet and I can eat as much  as I want? Sign me up!" Despite its outward appearance, though, a  low-carbohydrate diet is not a high-calorie diet. Two interesting things  will initially prevent over-consumption of calories. First, fat is a  very satisfying macronutrient. A protein- and fat-rich meal will satisfy  hunger more effectively than a high-carbohydrate meal. Second, severely  limiting carbohydrate consumption limits insulin secretion, and the  dieter will not experience the swings in blood glucose seen in the  low-fat diet. With a more consistent level of blood sugar throughout the  day, the low-carbohydrate dieter will experience fewer hunger pangs (and  mood and energy swings). Less perceived hunger results in a  self-selected reduction in calories consumed. So eating "as much as you  want" actually turns out to be less than you normally would eat with a  typical American pattern of eating lots of carbohydrates along with your  fats and proteins. There is a misconception out there that  low-carbohydrate diets drop your body fat faster and to a greater  magnitude than low-fat diets. You do lose "weight" very quickly in the  early stages of the low-carbohydrate diet. This is because the body  mobilizes and uses its existing carbohydrate stores (i.e., glycogen and  glucose) when you stop consuming them in your meals. That elimination of  stored carbohydrate carries with it an elimination of water weight as  well. Any time carbohydrate is stored in a cell, it is stored in  conjunction with water. Get rid of the carbohydrate and you will also  get rid of the water. The end result is a rapid loss of bodyweight that  is composed mostly of stored sugars and water and minimally of fat. But  that loss of carbohydrate and water is fast enough and large enough for  most dieters to perceive a difference in the mirror and on the scales.  Success makes you feel good and contributes to staying on the diet  longer. Once the initial carbohydrate losses have petered out, the body will then begin to tap into stored fat and the rate of fat loss will  increase and be similar in rate and magnitude to that seen in a successful long-term low-fat diet."

I just want to say - I violently agree with Dr. Kilgore, and would add that, as regards health, the water weight loss is as important as the fat loss.