I'm not familar with your challenge. But what I try to do is eat natural foods. Now if you had to eat nothing but natural foods (non-processed), that would be a real challenge. Every so often a nice pizza is a temptation

, or some other commercially prepared food.
What's natural foods? They are foods that are found naturally in nature without man-made additives, chemicals, and sweeteners etc. You can find these natural foods generally on the outside edges of a food supermarket.
To eat natural foods one hundred percent means making your own breads etc. from whole grains; eating things like fruits, nuts, seeds, vegetables, meats without adding anything except herbs and spices etc. It can be done but take a lot of time and effort. By eating natural wholesome foods, the vitamins, minerals, and fiber are generally so high, that taking supplements are not usually necessary. Also the calories are generally much lower in relation to the nutritional value, that a person's weight is easier to maintain. This is because you don't feel hungry after feeding the body what it needs - not just "empty" calories that you will find with a lot of processed foods.