The Geometric Framework for Nutrition provides a unifying model for exploring the complex relationships between nutrition and health. Interactions between the nutritional environment, physiology and disease outcomes are mediated via appetite and metabolic control systems, with gut, liver and brain playing key roles. In this talk I will present some of the latest data from experiments in which these relationships have been explored using nutritional geometry in mice, flies and humans. I will introduce data on the double burden of branched chain amino acids, the role of macronutrient ratios in shaping the microbiome, and on the regulation of protein appetite.