Foods listed in red or orange could be inflammatory causing to the body. Much like any inflammation, the body's natural defense mechanism is to encase the inflammation with water to try and heal the area; this can lead to water retention, which can result in "weight gain."
Chronic periods of inflammation with water retention will naturally acquire body fat to encase the chronically inflamed area. The body's water storage and electrolytes - sodium, potassium, and magnesium- may become imbalanced if the water and electrolyte reserves are continuously used up to encase the inflammation. This can then lead to problems with weight gain or "not being able to lose weight" regardless of dieting.
Removing the red and orange items for 6 - 8 weeks from the diet may allow the body a chance to heal and no longer be in such a state of inflammation. As a result, a person can lose weight without exercising or cutting calories by simply committing the foods in red and orange.
However, we do advocate a healthy amount of exercise being incorporated into daily living, and calories do play a role in overall weight loss.