<p>Obesity prevalence is increasing worldwide, and drives the rising prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD), currently the most prevalent chronic liver disease in all age groups. MASLD, like obesity, is linked to premature motality and increased risk of comorbidities. As in a Tango, the obesogenic environment and MASLD interact closely through complex interplays involving the gut–liver–brain axis. Once established, MASLD alters several metabolic responses to environmental mstimuli, promoting a feedback loop. It is therefore urgent to improve the awareness of the pathways leading to metabolic disease, focusing on pathophysiology, early diagnosis using non-invasive tools, environmental determinants, and multidisciplinary models of care. Efforts to combat obesity and MASLD must extend beyond simple clinical care and pills. Rather, we need multisectoral responses to protect public and environmental health, since many health systems remain passive, and therefore facilitate the onset consequences due to unnecessary and harmful body fat over storage. Care models must pivot to risk-based screening, early detection, tailored intervention, with mitigation of environmental hazards driving involuntary exposure. This includes early liver dysfunction assessment, access to lifestyle programmes, and digital tools for remote monitoring. Building on such needs, we joined important EU-funded initiatives FOIE GRAS, PAS GRAS, and PRIMA to advance knowledge on hepatic bioenergetics, gut–liver axis dysfunction, and gene–environment interactions, while testing lifestyle-based preventive strategies. We also implemented the 13Cmethacetin breath test, a novel non-invasive functional tool that detects subclinical hepatocyte dysfunction in individuals with obesity, even before structural changes or biochemical abnormalities appear in the liver. The detrimental Tango can be interrupted at the individual level by non-invasive diagnostics, personalised prevention, adequate phenotyping, and at the community level through cross-sectoral policies oriented toward equity, sustainability, and primary prevention. Strategic, integrated actions can transform global health by advancing not only longevity but also healthspan and resilience. The Tango between the obesogenic environment and MASLD urgently requires active partners, not passive spectators. Internal medicine is pivotal in coordinating this transition across settings and disciplines</p>