There are some good thoughts on the study here from the researchers:
The results defy the notion that fasting or dieting leads to gorging later; they also counter the idea that people have a genetically determined set point weight.
However, the study suggests a new strategy for losing weight. Although chronic lifestyle changes (eating healthier foods and getting more exercise) are preferable ways to lose weight, Levitsky said, a weekly fast might be another way to go.
Since it takes 10 to 14 days to recover the body tissue lost from a one-day fast, "Going without food for one day each week should produce a significant reduction in body weight over time," Levitsky said, now that we know that "fasting does not lead to overeating, and total recovery of body tissue does not occur within the week."
A useful study for those interesting in the science behind IF
One day of food restriction does not result in an increase in subsequent daily food intake in humans
The purpose of this study was to examine the effect of one day of food restriction on subsequent spontaneous daily food intake and the recovery of body weight in humans. Twenty-two, non-restrained females were fed from Monday to Friday for four weeks using food prepared and measured in the Cornell Metabolic Laboratory. For the first week, all participants ate ad libitum. For each subsequent Monday, participants were divided into three groups in which either they (a) ate ad libitum, (b) were restricted to eating 1200 kcal (5040 kj), or (c) were fasted. From Tuesday until Friday participants ate ad libitum. During each session, all food consumed as well as body weight were measured.
Body weight did not change following the day of ad libitum eating, but decreased significantly after the day of food restriction decreasing still further after fasting, indicating high compliance with study protocol. Although the loss in body weight was regained within four days, the recovery was accomplished without any increase in spontaneous food intake. Although no direct measurement of energy expenditure was made in this study, the results strongly suggest that decreases in metabolic rate play a more dominant role in the recovery of body weight following food restriction than the control of food intake.