The aim of the present chapter is to present a conceptual framework for examining associations between eating, drinking and wellbeing. The approach is exemplified by considering two topics which have received considerable attention, namely the effects of consumption of breakfast and ingestion of caffeine. It is argued that other aspects of diet can be considered in a similar way once the volume of research reaches appropriate levels. The first feature of the current approach to wellbeing is that it is multi-factorial. Research on diet and health has confirmed the view that there is more to health than the absence of disease. Being able to function efficiently, both mentally and physically, is an important part of wellbeing. Similarly, the absence of negative affective states (negative mood, stress, anxiety and depression) and the presence of positive emotions (positive affect, happiness, and life satisfaction) have long been recognised as key features of wellbeing. Previous research has investigated the relationship between diet and well-being, with some topics such as the effect of a healthy diet (e.g. consumption of breakfast, fruit and vegetables and oily fish) or a bad diet (e.g. junk food) being widely studied. Other aspects of eating and drinking require further attention (e.g. eating super-foods such as broccoli; effects of BMI; emotional eating; and consumption of foods which change the gut microbiome -pre-biotics and probiotics). There are three major problems with most of the previous research. First, the different dietary topics are often studied in isolation, which clearly misrepresents the real-life situation. Secondly, wellbeing is influenced by other established predictors (psychosocial factors such as stress, social support, personality and coping styles; health-related behaviours such as exercise, and sleep) and these are rarely controlled for. Thirdly, most of the research involves cross-sectional studies. What is now needed are multi-variate, longitudinal studies of eating, drinking and wellbeing. Such research will elucidate underlying biological mechanisms and develop practical approaches of preventing and managing negative effects and maximising positive ones.