Although we cannot predict which patient will or will not temporarily overshoot his or her optimal weight set point during a recovery process from a restrictive eating disorder, we do seem to have some scientific evidence that an overshoot is necessary so that the body might eventually return to its optimal fat mass to fat-free mass ratio.
Abdul Dulloo and his colleagues carefully assessed the comprehensive data from the Minnesota Starvation Experiment [AG Dulloo et al., 1990, 1996, 1997 and 1998], and found that in re-feeding the body preferentially restores fat relative to lean tissue, contributed by reduced thermogenesis, to support further adipose organ restoration; that there appear to be distinct signalling mechanisms in re-feeding from both fat mass and fat-free mass to trigger hyperphagia (extreme eating); and that we can surmise from these findings that the return to an optimal fat mass to fat-free mass ratio will be curtailed should a patient fail to refeed fully and allow for a possible temporary overshoot in weight to occur.
Because a recovered state from self-imposed starvation in clinical trials often refers merely to a return to BMI 18.5 and above (rather than a cessation of all weight gain and weight stabilization as a result of unrestricted eating), we see a large body of literature that indicates many 'recovered' patients that fit the clinical criterion of BMI 18.5 or above have disproportionately high levels of visceral fat compared to lean (fat-free) mass [L Scalfi et al., 2002; M Helba et al., 2009; J Hebebrand et al., 2007; MT García de Álvaro et al., 2007].
All that science is important.
If you just restore to a specific weight either by half-restricting throughout the recovery process or as soon as you reach a "target weight", then you set yourself up for disproportionate layers of visceral fat. That is known to correlate with negative health implications for you over your lifetime [MI Goran et al., 1999; T Cascella et al., 2002; JL Kuk et al., 2006].
Conversely, in the very few trials where recovery was identified with both extended inpatient and outpatient review and a criterion of "achieved maximum weight gain", then patients achieved average fat mass to fat-free mass ratios and returned to average gynoid (female) shape [CI Orphanidou et al., 1997].
Here's the deal: No one can predict your final optimal weight set point. It's unwise to assume anything about the process of recovery. While overshooting your optimal weight set point may occur, it may not. And it's probably even unwise to hope that you have overshot if you don't like the weight at which your body decides to settle in after several months of dedicated rest and re-feeding, because that can simply keep you locked into eating disorder focus on your weight defining your very existence.
It's not the food intake or extreme hunger that causes a temporary overshoot in weight, it is the need for the body to restore its optimal fat mass to fat-free mass ratio that causes food intake and extreme hunger when recovering from persistent energy deficits in the body.