If your metabolism is damaged through starvation and/or years of yo-yo dieting, yes you might gain a few pounds at first. If that does happen, my advise would be to NOT PANIC and stick with it. It's going to take some time and patience to heal your damaged metabolism, but it is possible.
I would suggest that you read The Schwarzbein Principle and The Schwarzbein Principle II for more information on what years of starvation and yo-yoing does to your metabolism and what best to do about it (hint...continuing to starve yourself and yo-yo isn't the answer!).
I'd also caution you against going into this with the mindset of being able to "pig out" on low carb foods. On low carb we are are to learn to eat until satisfied, but not stuffed and to eat a wide variety of protein, fats and vegetables.
Since you have very little to lose (less than 20 pounds), Dr. Atkins suggested that you skip induction and go right to the ongoing weight loss (OWL) phase at 25-30 grams of carb per day to start with and go from there. You may want to consider other low carb plans than Atkins (see the link already suggested) before you settle on a plan and definitely get the book for whichever plan you choose and read it thoroughly before you begin.
Best of success to you!