Colette- how long have you been low-carbing? what plan are you following, and do you have and read the book for that plan?
actually, after the first 4 days or so, most people experience a SURGE of energy, not the other way around. usually when people say they are having low energy, i see different scenarios...
1. they are not following any plan at all but doing their own
lc version without reading any books or being fully informed.
2. they are in induction, and are having normal sugar withdrawls, which pass after about 3-4 days.
3. they are deliberately eating less than 20 carbs trying to lose faster, or starving themselves trying to lose faster.
4. they are not taking vitamins and not eating enough veggies. veggies aren't optional, and low carb is NOT just steak, eggs and bacon cheeseburgers. if you are doing this, you're not following a real low-carb plan.
5. they have other health issues which need to be managed first, or in addition to, their low carb eating.
being in contact with a doctor can be quite helpful, especially if you have any other health issue besides weight.
in particular, if you are trying to do atkins, i can't stress enough: GET THE BOOK and read it. it will help you troubleshoot issues, because feeling lethargic is the opposite of what you would expect after a week on low-carb.