Understanding species responses to environmental changes and the potential for range shifts requires integrating both a whole-organism and molecular perspective, whilst investigating how environmental gradients shape thermal responses. Here, we did so by profiling whole-organism traits (i.e., growth, feeding rate, metabolic rate, thermal limits) and the metabolome, to investigate differences in functional trade-offs along a broad latitudinal gradient, using the intertidal gastropodLittorina littoreaas a model. We collected individuals from ten locations across a wide latitudinal gradient in the species non-native range in North America. Snails were exposed under laboratory conditions to one of 12 temperatures for 30 d, after which we characterised their phenotypes and their energy metabolisms, using a targeted metabolomics approach. We evidence that a large portion of the metabolomic variation underlines energetic trade-offs promoting thermal tolerance at the expense of growth. Furthermore, such trade-offs appear more pronounced in the warmer locations, given that individuals from warmer regions showed generally lower metabolite levels. Last, snails from locations with lower summer temperatures accumulated metabolites associated with cellular stress responses, explaining their greater thermal tolerance and acclimation capacity. Our integrative framework indicates that snails from colder (northern) regions possess a more effective molecular “toolkit” to cope with thermal stress, which improves their thermal acclimation capacity and heat tolerance, suggesting a future species range shift northward with the progression of climate change.