Acute Intervention to Assess the Impact of Practical Strategies for Healthy Eating

Obesity has reached epidemic proportions globally, alongside its associated comorbidities including cardiovascular diseases, diabetes and cancer. Effective weight management strategies are thus paramount to improve the population´s health. One of the key causes of obesity lies in excessive energy consumption derived from eating too large portions of food. In this context, practical tools to control portion size represent a promising, cost-effective strategy.This study will investigate whether using an optimized portion-control toolkit to consume a meal under controlled laboratory conditions has a positive effect on the nutritional quality of the meal as well as any benefits in physiological, cognitive, affective and behavioural outcomes.The study will involve 40 volunteers with overweight or obesity who will attend two lunch sessions at the Center for Nutrition Research of the University of Navarra (Spain) on two different days. At each session, participants will be invited to self-serve and eat a lunch from a cold buffet. On day one, participants will self-serve and season their food using control tools (conventional kitchen serving spoons and oil dispenser). On day two, participants will self-serve the same foods as on day one but using experimental tools (calibrated portion-control serving spoons and calibrated oil dispenser). A set of cognitive tests will be completed before, during and after the meal.Conventional and experimental tools will be compared in terms of the following variables: meal portion size and energy density, cognitive effort while serving food, cephalic and intestinal satiety responses, appetite sensations, energy adjustment post-meal, awareness of the quantities of the previously consumed foods and recalibration of portion size norms. Additionally, the study will explore acceptance for and intention to use the optimized portion control toolkit, as well as intention to change eating habits.It is expected that the findings from this study will shed light into the cognitive and physiological processes associated with portion control. It may also help to explain individual variations in the responses to obesogenic environments, which will hopefully lead to improved personalized interventions.

Inclusion Criteria:Adults aged between 18 and 65 yearsBMI between 27.5 and 39 kg/m-sq, except for Asian participants (BMI 26 to 39 kg/m-sq)Good gastrointestinal healthGood visual acuity or wearing contact lensesRegular eating habits (i.e. consuming lunch and dinner at least 5 days a week)Liking of at least one of the foods from the three major categories (vegetables, protein, and starch)Willingness to provide blood samplesAvailability to attend two clinical visits at lunch timeExclusion Criteria:Malnutrition (including dehydration; anaemia; blood donation within less than 3 months)Gastrointestinal disordersEating disorders (a score of 20 or more in the EAT-26)Elevated stress levels (a score of 27 or more in the PSS-14)Need to wear glasses to self-serve foodBeing on a diet to gain or lose weight (leading to >7.5% body weight change in the last 3 months)Food allergies or restrictions impacting food choices at the buffet meal (including veganism)Active medical conditions like diabetes, cancer, epilepsy, memory loss impacting on food behaviour and/or body weightTaking medications affecting appetite, body weight, memory or sight, except if the person has been on a stable dose for the past 3 months and no symptoms have been experiencedUsing a pacemaker/other electronic medical device that may interfere with the eye tracking equipment or softwareSmokers, drinkers, athletes and pregnant or lactating womenKnowledge that can affect the results of the study (e.g., nutritionists/dietitians, those with previous training in eating behaviour research)Participation in the preceeding qualitative study.Menstrual cycle in women will not be controlled for but day of last menstruation in pre-menopausal women will be recorded. Post-menopausal women will not be excluded; however, this detail will be noted at screening, with an individual's menopausal status (pre, peri or post).Candidates working shifts may be eligible if they are able to attend a clinical visit at least 12 hours since the last shift, to ensure they have sufficient sleep and their appetite sensations are not altered.