In the close examination of your case, it is understood that your well controlled diet is not giving sufficient calories to maintain weight. That is what causing a weight loss. Now, what is your weight goal? What is your weight now? I would recommend you to work with a registered dietician. It will help you to have a well planned exercise plan and diet plan which can help in maintaining weight and good health. A dietician can teach you how to determine how much food of how much calories is needed per meal and in what quantities. He will help in selecting nutrient rich food for a balanced weight and optimal health.