Effect of Feeding Status on Appetite and Eating Behaviour.

Primary outcomes

1. Dietary restraint

   Time frame: Once before the breakfast meal and once 90 minutes after the meal during each experimental trial.

   Dietary restraint is the cognitive effort or intention to consciously limit food intake of eating. Participants will complete assessments of the Three Factor Eating Questionnaire (TFEQ) (Stunkard et al., 1985) to assess restraint once at two different time points on each experimental trial in a randomised, counterbalanced fashion. The minimum score for restraint is 0 and the maximum is 20, with a higher score indicating higher levels of restraint.

2. Disinhibition

   Time frame: Once before the breakfast meal and once 90 minutes after the meal during each experimental trial.

   Disinhibition refers to the tendency to overeat in response to emotional, social, or situational cues, even when not physiologically hungry. Participants will complete assessments of the Three Factor Eating Questionnaire (TFEQ) (Stunkard et al., 1985) to assess disinhibition once at two different time points on each experimental trial in a randomised, counterbalanced fashion. The minimum score for disinhibition is 0, and the maximum is 16, with a higher score indicating greater disinhibition or loss of control over eating.

3. Hunger

   Time frame: Once before the breakfast meal and once 90 minutes after the meal during each experimental trial.

   Hunger reflects the subjective perception of appetite and the susceptibility to feelings of hunger and food cues. Participants will complete assessments of the Three Factor Eating Questionnaire (TFEQ) (Stunkard et al., 1985) to assess hunger once at two different time points on each experimental trial in a randomised, counterbalanced fashion. The minimum score for hunger is 0 and the maximum is 14, with a higher score indicating indicating greater susceptibility to feelings of hunger and greater responsiveness to food cues.

4. Unconditional Permission to Eat (UPE)

   Time frame: Once before the breakfast meal and once 90 minutes after the meal during each experimental trial.

   Unconditional Permission to Eat reflects a person's ability to allow themselves to eat a wide range of foods without guilt or unnecessary rules. It captures how flexible and trusting someone is toward their own hunger cues. Participants will complete the Intuitive Eating Scale-2 (IES-2) (Tylka & Kroon Van Diest, 2013) to assess UPE at two time points during each experimental trial in a randomised, counterbalanced order. Items are rated on a 5-point scale from 1 (strongly disagree) to 5 (strongly agree), with higher scores indicating a greater ability to permit oneself to eat when hungry without external restrictions.

5. Eating for Physical Rather Than Emotional Reasons (EPR)

   Time frame: Once before the breakfast meal and once 90 minutes after the meal during each experimental trial.

   Eating for Physical Rather Than Emotional Reasons reflects the extent to which individuals eat in response to genuine physical hunger rather than emotions such as stress, boredom, or sadness. This construct captures a healthy separation between emotional states and eating behaviour. Participants will complete the IES-2 (Tylka & Kroon Van Diest, 2013) at two time points during each experimental visit in a randomised, counterbalanced order. Items are scored on a 1-5 scale, with higher values indicating a stronger tendency to eat based on physical hunger rather than emotional triggers.

6. Reliance on Hunger and Satiety Cues (RHSC)

   Time frame: Once before the breakfast meal and once 90 minutes after the meal during each experimental trial.

   Reliance on Hunger and Satiety Cues measures how effectively individuals listen to and trust their internal bodily signals to guide when, what, and how much to eat. It reflects a mindful and attuned approach to eating. Participants will complete the IES-2 (Tylka & Kroon Van Diest, 2013) at two different time points on each study day in a randomised, counterbalanced fashion. Items are rated on a 5-point scale, and higher scores indicate stronger trust in one's internal cues of hunger and fullness.

7. Body-Food Choice Congruence (BFCC)

   Time frame: Once before the breakfast meal and once 90 minutes after the meal during each experimental trial.

   Body-Food Choice Congruence reflects how consistently individuals choose foods that support their physical functioning, health, and well-being. It captures a compassionate connection between how a person feels and the types of foods they select. Participants will complete the IES-2 (Tylka & Kroon Van Diest, 2013) at two time points during each experimental visit in a randomised, counterbalanced design. Items use a 1-5 response scale, with higher scores indicating greater alignment between food choices and physical self-care.

8. Hunger

   Time frame: Once before the breakfast meal and once 90 minutes after the meal during each experimental trial.

   Hunger represents how frequently and intensely participants felt hungry over the past week. Using the weekly Visual Analogue Scale (wVAS) (Womble et al., 2003), participants rate their overall hunger on a 100-mm line from 0 mm (not hungry at all during the week) to 100 mm (extremely hungry throughout the week). Higher scores indicate stronger or more frequent hunger sensations during the previous week.

9. Fullness

   Time frame: Once before the breakfast meal and once 90 minutes after the meal during each experimental trial.

   Fullness reflects how often or how strongly participants felt full across the previous week. Using the weekly Visual Analogue Scale (wVAS) (Womble et al., 2003), participants will complete the wVAS, marking fullness on a 100-mm scale from 0 mm (rarely or never felt full during the week) to 100 mm (felt very full very often throughout the week). Higher scores indicate more frequent or stronger feelings of fullness across the week.

10. Satisfaction with eating

    Time frame: Once before the breakfast meal and once 90 minutes after the meal during each experimental trial.

    Satisfaction reflects how content or pleased participants felt with their eating experiences during the past week. Using the weekly Visual Analogue Scale (wVAS) (Womble et al., 2003), participants rate satisfaction on a 0-100 mm line from 0 mm (not satisfied at all during the week) to 100 mm (extremely satisfied with eating throughout the week). Higher scores indicate greater overall satisfaction during the week.

11. Desire to Eat

    Time frame: Once before the breakfast meal and once 90 minutes after the meal during each experimental trial.

    Desire to eat reflects how frequently participants experienced an urge or motivation to eat during the previous week. Using the weekly Visual Analogue Scale (wVAS) (Womble et al., 2003), participants will rate this on the wVAS, from 0 mm (little or no desire to eat during the week) to 100 mm (strong desire to eat very often throughout the week). Higher scores indicate a stronger or more frequent desire to eat during the past week.