Did anybody feel run-down when starting low carb?

The good news is, I've lost 2 lbs this month using the food diary and trying to watch my calorie intake. Other good news, I saw my surgeon yesterday and we are submitting to my new insurance for RNY. This is much quicker than I thought it would be. I was planning on having to do the 6 month supervised diet, but my company changed insurance in January to Humana and the surgeon's office doesn't think they have this requirement. The bad news is I've put on 20 lbs since the first time I saw the surgeon last April (26 lbs gained and 8 lbs lost). He wants me definitely in a losing phase before surgery to help shrink my liver. I am stepping up my efforts, working toward the very low carb diet he recommends for 2 weeks pre-op. I probably have at least a couple months, but figured it doesn't hurt to start now and try to get in the habit. My husband started a month out before his surgery and it really got him off to a good start. Did other people feel run-down and sick the first day or 2 of Atkins or other low carb diet? I feel sick and headachy. My husband has a bug though, so it may just be that. Thanks! Caryl