A theory of predicting the growth of an animal following a period of nutritional limitation is proposed here. The theory consists of the following three propositions. Proposition 1: there is a scale of size, such that the growth rate following a period of nutritional limitation is that of normal animals at the same size. Proposition 2: any abnormalities in body composition at the end of the period of limitation will be corrected over time. Proposition 3: the rates at which abnormalities in body composition at the end of the period of limiting conditions are corrected, are always set by the conditions of rehabilitation. The propositions are connected with three other problems viz normal growth, growth under some limitation and the conditions needed by an animal to perform at its potential. These problems are dealt here by: (i) using a simple description of normal growth, (ii) considering the limitation by its effects rather by attempting to predict the effects of a given limitation, and (iii) using simple assumptions about protein and energy scales and requirements. The predictions of the theory are compared with experimental data, and a good qualitative agreement is found. Important conclusions from the theory are: (a) that it is essential to measure as fully as may be the state of the animal at the end of the period of limitation and to compare it with the state of normal animals and (b) that careful attention needs to be given to the choice and the description of the treatment, or preferably treatments, during the rehabilitation period.