CONCLUSIONS: The 2-part models of instrumental variables, which estimate the causal effects of obesity on direct medical costs, showed that the effect of obesity is greater than suggested by previous studies, which estimated only correlations. Much of the aggregate national cost of obesity—$260.6 billion—represents external costs, providing a rationale for interventions to prevent and reduce obesity.

J Manag Care Spec Pharm, 2021 Mar;27(3):354-366.
https://doi.org/10.18553/jmcp.2021.20410

HT to https://www.healthcare-economist.com/2023/02/08/estimating-the-economic-cost-of-obesity/