The important thing with a Low Carb diet is to remember that it goes hand in hand with High Fat (or Healthy Fat, if you prefer). That's why it is often called LCHF. The aim of LCHF is not just to cut right down on carbs and therefore starve yourself to slimness and ill health, but to re-train your body to make use of lovely healthy fats, which are bursting with all sorts of essential nutrients (unlike carbs).
Add eggs, cream, cheese, oily fish, bacon, fatty meats, nuts, seeds, avocados, olive oil etc to your diet and you will feel great and should keep the weight on.
Look at the Diet Doctor site for lots of ideas and encouragement concerning Low Carb.
Sally