Note—Modelling the Effect of Decreased Food Intake on the Activity Pattern of an Individual

The effect of decreases in food energy intake on the activity pattern of an individual may be described by an M^x/M/1 queueing model. λ represents the rate of activity arrival to the system. E(k) represents the average energy level at which the system performs, μ represents the rate at which the system processes energy units. p₀ = 1 − λE(k)/μ represents the probability of an idle system, of the system at rest. The model was validated by collecting data on food energy intake and activities from ten healthy young men. When food energy intake decreased an average of 500 kcal/day, 1 − p₀, the probability of a nonidle system, decreased from 0.431 to 0.413, p < 0.005. The greatest parameter change occurred in λ, which decreased from 0.245 to 0.235, p < 0.001. Thus, when food energy intake decreases, the activity pattern of an individual as represented by a queueing system changes: more time is spent at rest; less time is spent in moving activities.