I was told by one who was on the Adkins Diet that they could lose the weight because the body can't efficiently metabolize the fat calories without the Carbohydrates. I don't know if that is true, but I have seen a lot of folks lose weight on the Adkins diet.
For me, the issue is not losing the weight. The issue is keeping my arteries clear. For that we need to severely limit the saturated fat. Monounsaturated fat found in canola and olive actually lead to a Higher HDL and a lower LDL (very, very good). Pig fat is very bad. Olive fat is very good. Limiting saturated fat is only half the battle. As you said, exercise is required to burn the carbohydrate calories. The answer is a combination of exercise, moderate eating and low saturated fat. We will lose weight, and we can slow, stop or occasionally reverse artery disease.
The same here. I was put on a low fat low cholesterol diet because of hypertension and a high cholesterol count. I lost eight pounds in four weeks. Not a good thing for me because when I started this diet I was 5'6" and 146 lb's. I've modified the diet to gain back the weight.
My point here is in my case a low fat diet caused me to lose weight even when I didn't need or want to.