Growth in body size is the most prominent aspect of the ontogenetic development during individual life history. Necessarily, development depends on food availability and thus indirectly on the feedback from population foraging. Current ecological theory, however, ignores development and considers population dynamics as the balance between reproduction and mortality only. I will show that population models accounting for food-dependent growth in individual body size make predictions that match existing theory on population dynamics, only if food availability limits development and reproduction to the same extent. In contrast, when either development or reproduction is more food-limited, models accounting for food-dependent growth make very different and counter-intuitive predictions. For example, they predict that positive relationships can occur between population biomass and individual mortality and that a doubly handicapped consumer species, which is ousted by its competitor when competing for resources and is moreover preferentially preyed upon by a shared predator, nonetheless is the only consumer species surviving the predation pressure. I hence argue that the theory about population and community regulation needs to be revised to account for the effects of food-dependent ontogenetic development.