I always figured that on compensatory feeding days, my fish actually had to work for a living. And still ate and grew on natural food, which perhaps had experienced some days without fish eating it to get bigger/more numerous.
Rather than compensatory feeding, it may be better call that feeding supplemental feeding. So indeed your fish are doing well on natural foods and the supplemental feeding is boosting their gain. But this gain isn't compensatory growth in the context were using the term. If a fish is denied food or is placed into stress that reduces it food intake for a sufficient period of time ... there is window that follows when food is abundant where growth rate is high and food conversion is more efficient (lower FCR). This increased efficiency and increased gain "compensates for" the period of stress or starvation.
There must be a good explanation for it but it is probably multifaceted making it difficult to the isolate contributions of differing effect. One of the more obvious possible underlying causes is that fish lose weight but not frame during starvation. In other words they get a lot thinner but rarely shorter (unless the starvation is severe). When a fish is exposed to abundant food after such a period, the food is converted into growing fatter first. It just makes sense that this conversion is more efficient than having to grow larger bones, fins and organs. Another contributor may be suppressed gonosamitic growth. In other words the productions of eggs and sperm is subdued during compensatory growth. There may be other effects (e.g. in TP the consumption of food also increases ... they are hungrier than controls) but how does one separate all the these by their separable contributions?