Before I say anything I'd like the qualify that I'm only a first year med student, so basically at the bottom of the ladder. So take whatever I say with a grain of salt because I'm just parroting back that the teacher told me in class. Anyway here is goes...
So in theory the Atkins Diet works like this. They body need energy and the easiest form of energy to mobilize is going to be sugar. And all excess energy is going to be stored as fat, regardless of the source in which it came from. By eatting a low carbohydrate diet, you force your body to mobilize fat stores. For some reason that I forgot, you give yourself the illusion of being full when you are eatting a low carbohydrate diet, so you end up eatting less calories then you would have if you were eatting a "balenced" diet.
When you are converting this fat/protien into energy, you produce a lot of ketone bodies, and enter a state of ketosis. Because now you don't have glucose in your body any more, you need to fuel the brain somehow. And the brain being the picky thing that it is, like glucose, but in a pinch can use ketone bodies but it make it very unhappy to get ketone bodies.
Although ketosis is the desired state in the Atkins diet, in general ketosis is considered a bad thing. Like if you go to the doctor with ketosis, he's going to try to fix you.
Another problem with getting most of your calories through fat and protien is that protien contains a lot of nitrogen, and that will pose a problem to your system because all of that excess nitrogen is also bad for your system. So your body is going to be working really hard to excrete all that nitrogen, which gets transformed into ammonia and urea. Therefore, you are setting yourself up for kidney damage and dehydration. So if you are going on one of these diet at least do yourself a big favor and drink lots of water.
Here's also an example that the professor gave in class and take it for what it's worth.
So there are two American indian tribes. One that is situated in mexico and the other one which was new mexico or arizona (I forgot). Originally these two tribes were the same tribe but for some reason they got split into two groups, but you can assume that they have relatively similar genetic makeup and still have similar customs. However, over time their diets have drifted. The one in mexico was still eatting a tradition diet which was high in carbs and lower in fats and protien, however the one in the US switched to a diet that was low in carbs and high in fats and protien (too much government cheese perhaps ). Supposedly, the group in mexico is in general much healthier. However, this is not a controlled study, so they could be doing differing degrees of physical activity...
Just to make this a hot deal..... the "free" diet.
decrease food intake
increase physical activity
The goal is slow and steady weight loss. So we're not talking about huge cuts in food. I'm talking drinking water instead of coke. Eating one less snack than you usually do. etc...
In terms of physical activity. Remember physical activity does not equal exercise. Physical activity is walking up the stairs instead of taking the elevator. Parking further away than you normally would. Supposedly by fidgetting while you are sitting alone, you can burn enough calories to lose 10 lbs a year.
Losing weight is about making lifestyle changes rather than dramatic changes in weight.
On yeah, on another note. Metabolife. BAD! BAD! BAD! If you take Metabolife according to the manufaturer's suggestions you are getting 96 mg / day of epinepherine in the form of Ma Huang. The FDA recommends that doctors don't prescribe more than 24 mg / day. However, since metabolife is marketed as a nutritional supplement instead of a drug, the FDA has no jurisdiction.