Physiological and sensory influences on food intake in learnt satiety.
This Thesis examined the contributions of gastrointestinal and/or sensory influences to the
control of food intake in everyday life.
The postingestional effects at first exposure to an unfamiliar variant of a familiar food were
measured by correcting the observed satiating effects with what the eater expected them to be.
Physical forms of fat or chemical compositions of carbohydrate in familiar foods differed in the
timing of these postingestional satiating effects. Cream, which is hypothesised to empty rapidly
from the stomach into the intestine, satiated rapidly but transiently. Conversely, oil that was liable
to separation in the stomach produced a delayed and more prolonged satiating effect.
Learning about the postprandial effects of foods containing unfamiliar levels of a form of
nutrient occurred at first exposure to the after-effects of that variant: that is, sensory recognition of
that variant at the second exposure resulted in participants' predictions of its satiating effect
becoming more realistic.
A more prolonged satiating effect was expected from yoghurts containing a higher amount
of fat. At the same time, repeated exposure to a particular flavour of yoghurt induced more accurate
predictions of the postprandial effects of the amount of fat associated with that flavour.
Expected duration of hunger suppression by familiar and identifiable foods was related to
some extent to the observed differences in the duration of postingestional satiating effects of a
particular nutrient preparation. Pasta with an oily salad dressing was believed to satiate the eater for
longer than a pasta with a creamy salad dressing. Breakfast cereal labelled as high in fibre was
expected to produce a more prolonged satiating effect than protein and so on in order for starch, fat
These differences in expected postingestional satiating after-effects of a food or meal may
contribute to the planning of meal contents and perhaps timing. Unexpected timing of a meal or a
`surprise' in the postingestional effects of a food altered the composition of the next meal of another
sort from the participant's usual choice towards one giving the appropriate after-effects.