3 4 5
Here, a is still energy-in, b is still energy-out, and c is still the resultant change in body weight. But now the difference between a and b is multiplied by the unknown variable k, our genetic ‘black box’. We do not know the value of k and, in fact, it is imperative that we do not know, since if we did know it might turn out that the left side of the equation fails to equal the right side. If this were the case, we might decide to abandon the model.