Implementing Strategies for Eating Behaviour Modification Based on Portion Control

This is a pre-post intervention study designed to evaluate the feasibility of a self-applied weight management intervention based on portion control. A total of 40 healthy volunteers with overweight/obesity will take part in a 6-month intervention featuring 4 components: a portion control toolset; a manual including instructions for the use of the tools, dietary and activity recommendations, and behavioural strategies; a mobile app to motivate intervention engagement; and biweekly telephone support. The primary outcome will be Intervention adherence, assessed as the change in dietary energy density, meal nutrient composition and utilization of intervention components from start to end of trial. Other measurements (at baseline, 3 and 6 months from baseline) will include body composition, fasting biochemical parameters, inhibitory control, eating behaviour, portions size norms and acceptance of the intervention.

According to recent meta-analyses, portion control tools represent an acceptable and potentially effective strategy to aid in weight loss. However, how well these tools work depends on their consistent use and a good integration with other lifestyle modification strategies around body weight control and overall health. The present pilot study was designed to evaluate the feasibility of a self-applied weight management intervention based on portion control and to identify factors influencing adherence. The sample will consist of 40 healthy volunteers with overweight/obesity who will engage in a pre-post intervetion study lasting six-months. The intervetion will include four components: (1) a portion control toolkit (serving spoon and oil dispenser); (2) a phsyical manual with instructions for using the tools, dietary and physical activity recommendations, and strategies to build habits and improve mental wellbeing; (3) a mobile app to motivate intervention engagement; and (4) biweekly short telephone support. Adherence to the intervention will be the primary outcome, assessed on a fortnightly basis as the change from baseline in dietary energy density and change in meal nutrient composition plus frequency of using the intervention components. Other measurements that will be taken at baseline, 3 and 6 months from baseline, will be: body composition, fasting biochemical parameters, inhibitory control (only baseline and 6 months), eating behaviour, portion size norms and intervention acceptance. After 3 months of taking part in the intervention, a subset of the sample will participate in a nominal group session aimed at identifying barriers to intervention adherence and strategies to overcome them. The study results will inform the design of a full-scale controlled trial featuring the most successful components.

Eligibility Criteria:
Inclusion Criteria:

* Body mass index equal or above 27.5 kg/m2 (26.0 kg/m2 for those of Asian descent)
* Eating home-made meals at least 5 days a week
* Physically and mentally fit as assessed by the study researcher
* On-going pharmacological and hormonal treatment is accepted when this does not affect the study parameters (e.g. glucose response, appetite), and when the participant has been in a stable dose for at least 3 months
* Agreeing to undergo all the study procedures
* Being able to attend in person on 3 clinical investigation days during working hours
* Being able to understand and agree to sign the informed consent form

Exclusion Criteria:

* Being a regular smoker (that is, smoke more than 4 cigarettes a month)
* Being pregnant, breastfeeding or planning a pregnancy
* Exceed the alcohol consumption limit marked for the corresponding sex (more than 14 units in women and 20 units in men)
* Having followed a meal plan for weight loss and/or muscle mass gain in the 3 months prior to the start of the study intervention
* Having used a portion measuring instrument (e.g. scale, calibrated plate, etc.) consistently (at least in one main meal for at least 5 days a week) during the 3 months prior to the start of the study intervention
* Experiencing a weight change greater than 5% in the last 3 months
* History of relevant functional or structural anomalies of the digestive system, such as malformations, angiodysplasias, active peptic ulcers, chronic inflammatory or malabsorption diseases, or history of intestinal or bariatric surgery
* Suffer from some type of cancer, currently undergoing treatment for cancer, or when a period of at least 5 years has not elapsed since its eradication
* On-going chronic metabolic disease or obesity-related disease, or any systemic intestinal, liver or kidney disease such as type 1 or type 2 diabetes, severe dyslipidemia, uncontrolled thyroid function disorder, cirrhosis, inflammatory bowel disease, untreated anemia, etc. . (will not be excluded due to "fatty liver")
* Avoiding, being allergic, or being intolerant to the study foods or their ingredients (lactose free and regular chocolate milkshake)
* History of anaphylactic reaction to any food
* Taking any nutritional supplementation as a prescription medication that may affect the results of the study
* Taking over-the-counter nutritional supplementation (that is, without a medical prescription) that may affect the results of the study, unless the person is willing to stop it during the 6 months of the study duration and only when a minimum washout period of 14 days can be guaranteed prior to the basal measurements being taken
* A high incidence of attitudes and behaviors associated with eating disorders, expressed as a score greater than 20 on the 26-item Eating Attitudes Test scale (EAT - 26)
* Co-inhabiting with a study participant
* For former PORTIONS-3 study participants, when less than 3 months have passed since the last intervention visit (accepted if 3 or more months have elapsed).