I think the advantage of Atkins is that it kind of "preps" your body for weight loss by increasing your metabolism, reducing cravings, etc. But in the long run the result is the same -- burning more calories than you consume.
I agree in general. The calorie in/calorie out equation is the most reliable in predicting weight gain/loss. But there are some additional factors in play. First, it is much easier to digest, for example, simple sugars as compared to complex carbs. They end up in the bloodstream relatively unchanged. Fats flow a bit slower through the tube as well when compared to sugars. Plus, fat does tend to maintain a feeling of fullness longer than carb-based foods and especially sugars do.
There is also little energy expended when the body converts excess glucose to fat. It is comparatively more energy-intense when fat is converted to be used as energy. These are probably not huge differences, but they are important.
I think the advantage of Atkins is that it kind of "preps" your body for weight loss by increasing your metabolism, reducing cravings, etc. But in the long run the result is the same -- burning more calories than you consume.
I don't know that much about ketosis, but it seems that you may be metabolically "higher" when in the state of ketosis as compared to being in a normal carb-rich state.
Still not quite true. In my case I had several weeks where I would lose 6-8 pounds in 7 days (OTOH, I had several weeks where I would not lose an once - da&n plateaus!). If a pound of fat contains 3,500 calories, and I consumed ~1600 cal/day, then in those weeks I "burned" about 5,100 cal/day. That's not possible. What I was really doing was excreting unmetabolized ketone fragments without oxidizing them first (Atkins can be hard on your kidneys. Drink ALOT of water on it to keep them flushed). Your body is not a simple calorimeter. The calorie myth (in must equal out as energy equivilents) is one of the most pervasive nonsequitors out there about dieting.
There is one thing you are overlooking. That is that most fat comes as a by-product of the Krebs cycle which requires INSULIN. The amount of insulin your body secretes is determined by the amount of carbohydrates you injest! Basically, carbohydrates are converted by insulin in the Krebs cycle to glycogen to power the cells... but excess glycogen that is NOT used is then converted to FAT... human fat. When dietary fat is used instead of dietary carbs to power the body in Ketosis, insulin is not produced in quantity. Without the carbohydrates, the body does not produce anywhere near the amount of insulin and the excess dietary FAT is excreted instead of converted to human fat.
This means that if you injest 3000 calories of carbohydrates, you better be prepared to burn 3000 calories or the excess will be turned to fat. However, if you injest 3000 calories of dietary fat, it is not necessarily required to burn 3000 calories to avoid converting it to human fat... because the Krebs cycle is missing or minimal.