Weight Loss [on Atkins] depends on a number of things: Net Carbs, Glycemic Load, True Calories, Protein, etc...If you take in too many Net Carbs, you won't lose weight. If the Glycemic Load of your foods is too high, you probably won't lose weight. Taking in too little Protein can lead to muscle loss rather than fat loss. If you take in more True Calories than you put out, you will not lose weight...Although, if there is no insulin rush, you also won't gain.

Some folks could lose at 5,000 Calories/day [assuming 65% Fat, <20g CHO, that is 3,500 True Calories*.] Of course, most of us couldn't lose at that level. Make it 3,000 Calories/day [same assumptions] and you've only taken in 2,100 True Calories*. At 2,000 Calories/day [same assumptions,] you've taken in 1,400 True Calories*. Those last two are low enough for most men to lose at. Some women may have to stay at the lower intake to lose.

*True Calories -- It is a myth that Fat contributes a disproportionate number of Calories (9 Kcal/g vs 4 kcal/g). When your body breaks fat down into Ketones, it expends 4 kcal/g. That means, after subtracting the amount of energy needed to get Calories from the Fat, you arrive at a Net figure of 5 Kcal/g...much closer to the 4 Kcal/g for Carbs and Protein. In fact, Protein's True Calories may also be lower as it not only takes energy to use, but a substantial amount is used by the body for functions other than energy. But, since I can't say how much is actually not used for energy, I have to assume all is capable of being used for energy. True Calories reflects 5 Kcal for every gram of Fat, rather than the 9 Kcal per gram the FDA has mandated Food Makers use.