My dad had a serious illness—then he started eating McDonald’s, and the results shocked me

Years ago, my 84-year-old dad, who had always prioritized his health with tennis, a balanced diet, and outdoor activities, was diagnosed with pulmonary fibrosis. The news was shocking but explained his worsening symptoms—shortness of breath, a persistent cough, and significant weight loss. Doctors suspected his decreased oxygen intake was reducing his energy and appetite. (Video: Getty Images)