The GI MRI Research group at the University of Nottingham has been developing new, non-invasive magnetic resonance imaging (MRI) techniques to image the gastrointestinal tract. In collaboration with food manufacturer Unilever, the investigators want to image the abdomen of healthy volunteers after consumption of test meals of varying volume and energy density to determine levels of gastric distension and investigate possible correlations of this with the subjects' sense of satiety.

The tone of the proximal stomach decreases on meal intake through a process of gastric accommodation, aimed at increasing the capacity of the stomach. An increased gastric volume progressively distends the stomach, and this distension has been shown to have an inverse relationship on appetite. The link is assumed to be based on activation of mechanoreceptors lying in the walls of the stomach. On activation, vagal discharges are triggered, leading to activation of hypothalamic neurons and regulation of feelings of satiety. Gasrtric emptying is also regulated by duodenal feedback mechanisms triggered by the arrival and amount of nutrients.

Based on current knowledge, a high volume test meal would be expected to produce more gastric distension and satiety over a low volume test meal, and a low energy density food would be expected to empty from the stomach faster than a high energy density food. Going on this premise, study test meal 2 would be expected to empty faster than study test meal 1. These phenomena will be investigated using non invasive Magnetic Resonance Imaging (MRI) methods. MRI can measure gastric volumes serially and non-invasively with high spatial resolution. Ultimately, the findings from this study will provide novel insights on mechanisms of gastric distension and satiety.

Inclusion criteria:

• Apparently healthy; no medical conditions that might affect the study measurements (as determined by the study physician)
• No use of medication that would interfere with the study measurements (as determined by the study physician)
• No use of antibiotics in the 3 months before the study or during the study
• No reported participation in another nutritional or biomedical trial 3 months before the study or during the study
• Being used to eating 3 meals daily
• BMI: 20 - 35 kg m-2
• No reported participation in night shift work 2 weeks prior to the study or during the study
• Not taking part in strenuous exercise ≤10 hours/week
• Not consuming more than 21 alcoholic test meals in a typical week
• Not presently a smoker
• No reported weight loss or gain of more than 10 % of bodyweight for 6 months before the study
• No eating disorder
• No MRI contraindications; i.e absence of metal implants, infusion pumps and pacemakers, as assessed by a MRI safety screening questionnaire

Exclusion criteria:

• High or very high restrained eater
• Use of any medically- or self-prescribed diet for the duration of the study
• Allergies or food intolerances