Nutrition is a fundamental mediator of ecological processes, shaping foraging behaviour, performance, population persistence and community structure across ecosystems. Traditional foraging theory has centred on unitary measures of nutrition, such as energy maximisation, as the key driver of food selection. However, a large body of work in nutritional ecology has transformed our understanding of foraging in terrestrial systems by demonstrating the important role of nutrient balance in feeding and its consequences. This perspective is underutilised in marine research and conservation. Although detailed dietary data, including stomach content analysis, remain fundamental to understanding predator ecology, identifying what predators eat may no longer be sufficient to predict their responses to climate-driven changes in prey communities. Instead, we must ask whether potential changing diets continue to provide the nutrient balance required to sustain growth, performance and population persistence. A nutrient balance perspective could offer powerful insights into marine predator ecology and management, from predicting habitat use and migration to understanding population declines or changes in diet with warming oceans. Nutrient balance is, however, a more complex nutrition paradigm with more stringent data requirements than simpler measures such as food or energy-based approaches and poses specific challenges for research on marine predators, such as sharks. Here, we introduce the Nutritional Geometry Framework (NGF), a modelling approach that has been applied in terrestrial systems for examining the role of nutrient balance in foraging ecology. We illustrate its application using select terrestrial examples, then present an example from shark research. As ocean temperatures rise and prey communities shift under climate change, understanding the nutritional dimensions of predator–prey interactions is becoming increasingly critical. By framing shark foraging through the lens of nutrient balancing, we can better predict species responses to changing environments and improve the management of predators in dynamic marine ecosystems.