You can actually have berries from the get go, up to 2 c. a day, but that should then be your only fruit of the day. They are low in sugar, high in fiber and antioxidants, and thus supportive. This program is designed to "hit 'em hard and fast” for a short three weeks. Then bring in the leaky gut healers and improve the microbiome in the lower bowel, so there is comprehensive support of the immune system and rebuilding of the terrain, so the body itself does not accommodate overgrowth and the diet does not support it. Things get better over time. Once the terrain is improved, it's a case of "if you build it, they will come." Benefits and improved results continue long after the program ends.