Anything that he does over and above merely staying alive will be defined as work, and is supported by "work calories" which he takes in.Work calories are used not only for what we call work in common speech; they are also required for all forms of enjoyment, from swimming and automobile racing to playing music and writing poetry.Put another way, there is no "technical solution" to the problem.I can win only by giving a radical meaning to the word "win." I can hit my opponent over the head; or I can falsify the records.
It is fair to say that most people who anguish over the population problem are trying to find a way to avoid the evils of overpopulation without relinquishing any of the privileges they now enjoy.
(The case of perpetual wide fluctuations above and below zero is a trivial variant that need not be discussed.) When this condition is met, what will be the situation of mankind? It is not mathematically possible to maximize for two (or more) variables at the same time.
Specifically, can Bentham's goal of "the greatest good for the greatest number" be realized? This was clearly stated by von Neumann and Morgenstern,  but the principle is implicit in the theory of partial differential equations, dating back at least to D'Alembert (1717-1783).
The population problem cannot be solved in a technical way, any more than can the problem of winning the game of tick-tack-toe.
Population, as Malthus said, naturally tends to grow "geometrically," or, as we would now say, exponentially.
It is easy to show that the class is not a null class. Consider the problem, "How can I win the game of tick-tack-toe?