Investigation of the underlying energy-regulating mechanisms of nuts: implications for nutrition labelling and strategies to promote nut consumption

Chronic disease is an ongoing source of poor health, and conditions such as cardiovascular disease and overweight and obesity are highly prevalent in Australia. Nuts are a core food associated with a range of health benefits; however, global consumption, including in Australia, is low. Previous research acknowledges consumer concern regarding the potential impact of nut consumption on body weight as a barrier to nut intake. While nuts are an energy-dense food, the evidence suggests that regular consumption is not associated with weight gain. Some proposed energy-regulating mechanisms of nuts include lower metabolisable energy (due to some fats within nuts being encapsulated within thick cell walls and not easily accessed and digested), reduced subsequent energy intake due to post-consumption appetite regulation (energy compensation), and increased energy expenditure. Currently, the energy content on nutrition labels in Australia is estimated based on Atwater factors, which do not account for the lower energy availability, hence may over-represent the available energy from nuts, and potentially deter the inclusion of nuts in habitual diets. Furthermore, energy intakes from nuts may be overestimated among consumers and other stakeholders. The aim of this thesis is, therefore, to synthesise evidence on the energy-regulating mechanisms of tree nuts and peanuts, and to explore the potential influence of these mechanisms on population energy intakes and strategies for labelling and promotion of nut intake. The research hypothesised that the metabolisable energy of nuts will consistently be lower than energy predicted using Atwater factors and that nut consumption will reduce subsequent energy intake and increase energy expenditure. Furthermore, energy intakes estimated using metabolisable energy values of nuts will be lower than the conventional Atwater method in Australian nut consumers, and while knowledge and practices regarding nuts will vary among consumers and other stakeholders, promoting the metabolisable energy of nut products may encourage nut consumption.