Sensitivity of the prevalence of obesity to different control programs. Effectiveness of interventions is measured by equilibrium prevalence as a function of relative reduction in certain parameter(s). A &C. The prevalence when single parameters (ε, β, 1/γ and σ) are independently varied. B &D. Comparison between the primary prevention (reducing α) and the secondary prevention (reducing κ). The baseline value of β is set to be low in panels A and B (1.99 × 10-7 per year), while panels C and D shows the case when β is set at high (4.33 × 10-7 per year).