The TFA carefully outlines country-wide factors; but treating the U.S. as a monolithic entity in terms of health care access and risk factor prevalence means missing major factors that explain why the outcomes are poorer than other health systems. Regional disparities in certain disease prevalence, risk factors and economic disadvantage all have nearly superimposable maps.
Research has found that people who follow the Mediterranean diet tend to live long, healthy lives. It's not designed for weight loss, merely a specific selection of healthy foods. https://www.healthdirect.gov.au/mediterranean-diet