If you eat flax seed it will kill the toxins in your body and give you more energy to exercise.
You know how to do this safely
Restrict calories and exercise. Take in less than you put out.
To not gain the weight again make those changes in your life that you have to. Eat what you need to operate your body and exercise regularly . Simply and safe.
The better way of losing way is : Eating less and eat only the vegetables and fruits with a little of chicken as other meats like pork and beef are easy to take weight.
I am not a vegetarian, but I like eat vegetables and fruits, sometimes with a little meat like chicken, then my weight does not change. I am slim.