Comprehensive Intervention for Changing Eating Habits Through Portion Control (PORTIONS_V_RCT)

Participants will receive a comprehensive 12-month intervention focused on changing eating habits through portion control. The intervention will include four components to promote lifestyle modification: (1) an educational guide with recommendations on nutrition, well-being and physical activity; (2) a portion-control toolset (calibrated oil dispenser and portion control serving spoon); (3) a healthy and sustainable recipe book; and (4) a mobile application to foster engagement with the intervention. Participants will also receive 6 follow-up telephone calls during the intervention period and will attend 4 clinical investigation days and 2 group sessions (with an additional 2 optional group sessions). A subsample of participants will undergo a focus group session (n=30) or functional magnetic resonance imaging (n=20).

Self-applied, multicomponent intervention with a previously validated portion control toolset

• Beteendeförändring
• Livsstilsförändring

Participants will receive a 12-month enhanced standard intervention based on printed nutrition and physical activity recommendations/guidelines from official health and nutrition organizations (i.e., WHO). The intervention will include general dietary advice, recipes and physical activity guidelines. Participants will also receive 6 follow-up telephone calls during the intervention period and will attend 4 clinical investigation days and 2 group sessions (with an additional 2 optional group sessions). A subsample of participants will undergo a focus group session (n=15) or functional magnetic resonance imaging (n=10).

Active comparator with same level of follow-up as experimental group

• Beteendeförändring

Change in waist circumference (cm) from baseline will be assessed over the 12-month intervention period. Waist circumference will be measured using standardized anthropometric procedures

Dietary energy (in kcal) and Dietary volume (in g) will be combined to obtain Dietary energy density (kcal/g).

Dietary nutrient composition (in g) will be defined as the average % energy provided by macronutrients, obtained from the 24 h dietary record

Dietary nutrient composition (in % energy) will be defined as the average % energy provided by macronutrients, obtained from the 24 h dietary record

Number of times the intervention spoon has been used in a period of 24 h (experimental arm only)

Number of times the oil dispenser has been used in a period of 24 h (experimental arm only)

Number of times the intervention guide has been used in a period of 24 h

Number of times the intervention app has been used in a period of 24 h (experimental arm only)

Number of times the cookbook has been used in a period of 24 h

Number of times the intervention spoon has been used in a period of 15 days (experimental arm only)

Number of times the oil dispenser has been used in a period of 15 days (experimental arm only)

Number of times the intervention guide has been used in a period of 15 days

Number of times the intervention app has been used in a period of 15 days (experimental arm only)

Number of times the cookbook has been used in a period of 15 days

Height will be measured in m using a stadiometer

Weight will be measured in kg using Tanita scales

Waist circumference will be measured in cm using a measuring tape

Hip circumference will be measured in cm using a measuring tape

Neck circumference will be measured in cm using a measuring tape

Weight will be measured in kg

Body Mass Index will be calculated from weight and height as kg/m^2

Waist to hip ratio is defined as the ratio of the waist circumference (cm) to the hip circumference (cm)

Body fat composition will be quantified as fat mass (in kg, %) from a body composition analyser

Fasting blood glucose levels (mg/dL)

Fasting blood insulin levels (mIU/L)

Fasting blood triglycerides levels (mg/dL)

Fasting blood total cholesterol levels (mg/dL)

Fasting blood HDL-cholesterol levels (mg/dL)

Fasting blood LDL- cholesterol levels (mg/dL)

Fasting blood ghrelin levels (pg/mL)

Fasting blood leptin levels (ng/mL)

Fasting blood GLP-1 levels (pmol/mL)

Average amount of yogurt with granola consumed per unit of time (g/min), based on validated methodology (Yeomans, 2000)

Average amount of yogurt with granola consumed at each bite (g), based on validated methodology (Yeomans, 2000)

Average time used to eat a yogurt with granola (min), based on validated methodology (Yeomans, 2000)

Average change in eating rate (g/sec-squared), based on validated methodology (Yeomans, 2000)

% error in chosen portion sizes for starch, protein and vegetables of a virtual meal vs recommended portion sizes (based on Brunstrom & Rogers, 2009)

% error in chosen nutrient content of a virtual meal vs recommended nutrient content (based on Brunstrom & Rogers, 2009)

Neural activity associated with food reward and eating- related sensations, assessed using functional magnetic resonance imaging (fMRI) during exposure to food-related auditory stimuli, based on Carnell et al., 2017 (Subsample n=30 only)

Gut microbiota diversity and abundance of bacterial taxa associated with metabolic status, adiposity, mental health, and eating behavior

Food addiction symptoms assessed using the Yale Food Addiction Scale (YFAS), validated by Granero et al., 2018

Automaticity of eating-related habits assessed using the Self-Report Behavioural Automaticity Index (SRBAI), validated by Gardner et al., 2012

Individual profile defined by the combined Restraint (0-21 points), Disihnibition (0-16 points) and Susceptibilty to hunger (0-14 points) sub-scales scores of the Three Factor Eating Questionnaire (TFEQ), validated by Stunkard & Messick, 1985. Restraint values above 11, disinhibition values above 8 and susceptibility to hunger values above 4 are considered worse outcomes (i.e. risk for development of obesity and other eating disorders)

Dietary energy (kcal) will be obtained from the 24 h dietary record

Dietary volume (g) will be obtained from the 24 h dietary record

Handgrip strength will be measured in kg using a dynamometer

Score in the Eating Attitudes Test-26 (EAT-26), ranging from 0-78 points, validated by Garner et al., 1982. Scores above 20 suggest a higher risk for presence of potential eating disorders

Score in the short-form International Physical Activity Questionnaire (IPAQ), expressed as metabolic equivalent of task (MET)-minutes per week (Craig et al., 2003). Higher MET minutes indicates higher levels of physical activity.

Score in the World Health Organization Quality of Life-BREF (WHOQOL-BREF) questionnaire (The WHOQOL Group, 1998). Higher scores indicate a higher perception of quality of life.

Frequency of consuming homemade meals via self-reported questionnaire

Frequency of consuming take away meals via self-reported questionnaire

Responsible person for cooking at home, via self-reported questionnaire

Liking for the foods to be used in the intervention, via self-reported questionnaire (100 mm visual analogue scale)

Familiarity with the foods to be used in the intervention, via self-reported questionnaire (100 mm visual analogue scale)

Shortened version of the pre-piloted on-line Beverage Portion Size survey (Self-reported questionnaire assessing caloric beverage intake and awareness of beverage portion sizes) (Vargas-Alvarez et al., 2022)

Validated questionnaire (Carter & Jansen, 2012) used to identify eating patterns associated with the risk for obesity. It consists of 25 items answered on a 5-Pt intensity scale. The information collected can be used qualitatively, to identify problematic behaviors, or quantitatively by adding the direct scores. Scores greater than 50 suggest a moderate to high frequency of behaviors associated with obesity

Self-reported questionnaire based on previous studies (Almiron-Roig et al., 2023) asking about special dietary needs, pregnancy, lactation, menopause, history of eating disorders, history of mental illness, incompatible medical conditions (e.g., cancer, diabetes, memory loss), regular medication including nutritional and other supplements

Fat mass distribution (trunk, arms, legs), fat-free mass (kg, %), fat-free mass distribution, visceral fat score, basal metabolic rate (kcal/day)

Score in the NEO-Five Factor Inventory (NEO-FFI) 60 item validated questionnaire (Costa & McCrae, 1989). The score for each central domain of normal personality defined by the Five-Factor Model of personality (neuroticism, extraversion, conscientiousness, agreeableness, and openness to experience) is calculated. A higher score on a scale assessing a certain personality domain indicates a stronger expression of traits associated with this particular domain

Score in the Perceived Stress Scale-14 (PSS-14) validated questionnaire (Cohen et al., 1983). Scores ranging from 0 to 13 suggest low stress, scores ranging from 14 to 24 suggest moderate stress, and scores above 27 suggest high perceived stress

Score in the Trait Meta-Mood Scale-24 (TMMS-24) validated questionnaire (Salovey et al., 1995). The score for three different dimensions of emotional intelligence are calculated. To obtain a score for each factor, items 1 to 8 are added for the emotional attention factor, items 9 to 16 for the emotional clarity factor, and items 17 to 24 for the emotional repair factor

Score in the Profile of Mood States (POMS) validated questionnaire (McNair et al., 1971). The score for six different dimensions of mood (tension, anger, fatigue, depression, confusion, and vigour) is calculated. A higher score on a scale assessing a certain mood dimension indicates a stronger expression of associated feelings. The resulting scores will range from -24 to 177, with lower scores indicative of people with more stable mood profiles

Self-constructed scale evaluated with the sum of scores (1-10) for 5 items (based on Borkovec & Nau, 1972). The 5 items include rating the intervention's logic, satisfaction, recommendability, expected usefulness, and the respondent's readiness to follow it. A higher score reflects a more positive expectation towards the upcoming intervention

Self-constructed scale evaluated with the sum of scores (1-10) for 5 items (based on Nau & Borkovec, 1972). The 5 items include rating the intervention's logic, satisfaction, recommendability, usefulness, and the respondent's readiness/intention to continue with it. A higher score reflects a more positive opinion towards the experienced intervention

Previously piloted questionnaire (Almiron-Roig et al., 2016) including 5-Pt Likert scores for portion tool attractiveness, fits within lifestyle, embarrassment, ease of use, perceived effectiveness and resistant to use. An average score of 1 or 2 indicates low acceptance, 3 neutral, and 4 or 5 high acceptance (experimental arm only)

Single scale instrument measuring the level of intention to use each component from 0-100 on a 100 mm visual analogue scale (previously piloted questionnaire, Almiron-Roig et al., 2016) (experimental arm only)

System Usability Scale (SUS) (based on Brooke, 1996). Includes ten 5-Pt Likert questions of which 5 items are scored positively (pleasant, easy to use, good functionality, quick to learn, safe), and 5 items are scored reversedly (complex, requires support, inconsistent, complicated to use, requires learning). A higher overall score indicates higher perceived usability (experimental arm only)

Single scale instrument measuring the level of intention to use the intervention app from 0-100 on a 100 mm visual analogue scale (previously piloted questionnaire, Almiron-Roig et al., 2016) (experimental arm only)

Self-constructed questionnaire including 20 items answered with a 5-Pt Likert scale. The first 10 items assess content of the guide (credibility, coherence, usefulness, applicability) and the second 10 items assess format (organisation, word choice and communication style). A score <60 indicates poor assessment (the tool cannot be used in clinical practice as it stands); a score between 60-79 indicates the tool needs revision before implementation; a score of 80 or above indicates the tool is well rated by potential users and may be useful in clinical practice

Single scale instrument measuring the level of intention to use the intervention guide from 0-100 on a 100 mm visual analogue scale (previously piloted questionnaire, Almiron-Roig et al., 2016)

Self-constructed questionnaire including 6 items answered with a 5-Pt Likert scale. The items assess coherence, usefulness, applicability, contents, word choice and communication style. A score <18 indicates poor assessment (the tool cannot be used in clinical practice as it stands); a score between 18-24 indicates the tool needs revision before implementation; a score of 24 or above indicates the tool is well rated by potential users and may be useful in clinical practice

Single scale instrument measuring the level of intention to use the Cookbook from 0-100 on a 100 mm visual analogue scale (previously piloted questionnaire, Almiron-Roig et al., 2016)

Monthly questionnaire asking about types of meals in which the serving spoons were most frequently used in the last 2 weeks (experimental arm only)

Monthly questionnaire asking about types of meals in which the oil dispenser was most frequently used in the last 2 weeks (experimental arm only)

Monthly questionnaire asking about guide sections most frequently checked in the last 2 weeks

Monthly questionnaire asking about cookbook sections most frequently checked in the last 2 weeks

Monthly questionnaire asking about app functions most frequently used in the last 2 weeks (experimental arm only)

Self-constructed interview to verify participants' compliance with arrival time, physical activity and dietary requirements and any change in medication occurred prior to each clinical investigation day

Taste detection thresholds for bitter, sweet, sour, and salty tastes, assessed using paper taste strips impregnated with the corresponding taste stimuli

Qualitative information on barriers to adherence encountered after 6 months of intervention, and participants' proposed solutions or strategies to overcome these barriers, collected through focus group discussions (subsample only n=45)

Self-constructed interview to assess participant's overall experience with the intervention at study end (items include previous tools/methods employed, satisfaction with intervention, consistency of use, barriers experienced and intention to continue using the components)

Adverse events are defined as any new unfavourable and unintended event that the participant has experienced during the course of the intervention or treatment. AE do not necessarily have a causal relationship with the intervention. Examples of AE may include:

• Abnormal laboratory findings
• Symptoms (e.g. gastro-intestinal discomfort, headache)
• Disease
• Worsening of existing symptoms

Serious adverse events (SAE) are defined as any untoward medical occurrence that:

• Results in death
• Is life-threatening at the time of the event
• Requires in-patient hospitalization as in extension of an already planned hospitalization or requiring a new (unplanned) hospitalization
• Results in persistent or significant disability or incapacity
• Is another important medical event

Fasting scores for hunger measured on a 100 mm visual analogue scale, taken before consumption of yogurt with granola (validated questionnaire based on Hill & Blundell, 1982)

Fasting scores for fullness measured on a 100 mm visual analogue scale, taken before consumption of yogurt with granola (validated questionnaire based on Hill & Blundell, 1982)

Fasting scores for thirst measured on a 100 mm visual analogue scale, taken before consumption of yogurt with granola (validated questionnaire based on Hill & Blundell, 1982)

Fasting scores for desire to eat measured on a 100 mm visual analogue scale, taken before consumption of yogurt with granola (validated questionnaire based on Hill & Blundell, 1982)

Fasting scores for prospective intake measured on a 100 mm visual analogue scale, taken before consumption of yogurt with granola (validated questionnaire based on Hill & Blundell, 1982)

Fasting scores for nausea measured on a 100 mm visual analogue scale, taken before consumption of yogurt with granola (validated questionnaire based on Hill & Blundell, 1982)

Age will be recorded in self-reported age in years at recruitment point

Sex will be recorded as self-reported sex assigned at birth (male, female)

Gender will be recorded as self-identified gender with one of these options: man, women, other (describe if you wish), prefer not to say.

Education will be recorded as self-reported maximum education level achieved with one these options: without education; prmary education; secondary education; seconary vocational education; high vocational education; university degree; other (specify).

Marital status will be recorded as self-reported status with one of these options: married, civil union, separated, divorced, widowed, single (never married), other (specify).

Self-reported country of birth will be recorded using an open-ended question "country of birth"

Employment will be recorded as self-reported professional situation with one of these open-ended questions: Current job (if you have); Last job (in case of retirement, permanent leave, unemployment, etc.); Without a current or past job

Smoking status will be recorded as self-reported habits with one of these options: never smoked; ex-smoker (for more than 3 months); current smoker; occasional smoker (fewer than 4 cigarettes per month).

Alcohol intake will be recorded as self-reported weekly alcohol unit consumption (1 unit = can, glass or shot).