"When someone breaks up with diet culture to focus on healing their relationship with food, body, and self, it is not uncommon for weight gain to occur. Chances are the weight of a person, after years of chronic dieting and disordered eating behavior, is not their natural set point. As they let go of their tight grasp for control and the reins on their eating behavior are loosened, it is extremely common for there to be some backlash as they work on neutralizing food and eating while becoming more attuned to internal cues of hunger and fullness.
This is often uncomfortable for many reasons: 1) the person is used to having a ton of food rules to follow so they often feel like they are flailing when they let go of the culture’s ideas of 'right/wrong, good/bad, healthy/unhealthy', and 2) weight gain tends to occur as eating is normalized and the focus turns toward healing their relationship with food/body (which is only possible when thoughts about controlling the size, shape and weight of the body are put on the back burner)." » Be Nourished