The effects of wholegrain processing on appetite: randomised crossover trial in adults with type 2 diabetes

Aims: Recent observational data indicate higher ultra-processed food intakes are associated with a broad range of adverse health outcomes. Experimental studies on why this might be are lacking. We have considered the effects of wholegrain processing on measures of appetite in free-living adults with type 2 diabetes. Materials and methods: Participants were randomised to two interventions of two-weeks duration, separated by washout. Interventions were nutrient-matched wholegrain foods that differed by the amount of processing. Self-reported hunger and satiety were indicated on visual analogue scales before or after meals for four days at baseline and the end of each intervention. Metabolite markers of appetite were measured pre and post intervention in fasting plasma. Results: 31 adults (63 ± 13 years old, BMI 32.4 ± 7, HbA1c 7.5 ± 3.4% (59 ± 14 mmol mol^-1)) commenced the trial, 28 (90%) completed both interventions. Wholegrain consumption, as measured by alkylresorcinols, was balanced between interventions. Self-reported pre-meal hunger was consistently lower at breakfast (MD, mean difference 0.49/10 95% CI 0.03 to 0.94), lunch (MD 0.67/10 95% CI 0.09 to 1.25), and dinner (MD -0.71/10 95% CI 0.19 to 1.23) during the intervention of less processed whole grains when compared with pre-intervention measures, however this did not result in a difference between interventions. Change in metabolite markers of appetite did not differ between interventions. Conclusions: A significant difference in hunger or satiety between less and more processed whole grains over intervention periods of two weeks was not detected within the current trial. Further experimental studies are needed to consider the potential effects of food processing on physiological processes such as appetite to provide mechanistic understanding behind observations of highly processed food intakes and adverse health outcomes.