Portion Size Effects on Mood

Age: 18 - 65

Sex: Any

Trial Phase: Academic

Sponsor: The University of Tennessee, Knoxville

Must not be taking: Appetite suppressants

Disqualifiers: Pregnancy, Athlete, Therapeutic diet, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Compensation: Varies

Number of Visits: Unknown

Duration: 1 year

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial explores how different portion sizes of food can affect mood. Researchers will divide participants into groups to receive decreased, increased, or mixed portion sizes, while a control group will receive standard care with equal portions. The aim is to determine if changing food amounts can influence happiness or stress levels. Ideal participants are non-smokers, not on medications affecting appetite, and have no food allergies.

As an unphased trial, this study offers a unique opportunity to contribute to understanding how food portions impact emotional well-being.

Will I have to stop taking my current medications?

If you are taking any medications that affect appetite or food intake, you will need to stop taking them to participate in this trial.

Is there any evidence suggesting that this trial's treatments are likely to be safe?

Research shows that changing portion sizes is generally safe. Studies on reducing, increasing, or mixing portion sizes report no harmful effects. When portion sizes are reduced, research examines the impact on energy intake and appetite, finding no safety issues. Similarly, studies on increasing portion sizes find no harmful effects and explore changes in mood, including the gut-brain connection. For mixed portion sizes, studies again report no safety concerns, focusing on energy intake. Overall, evidence suggests that changing portion sizes is well-tolerated without negative effects. ^{1 2 3 4 5}

Why are researchers excited about this trial?

Researchers are excited about this trial because it explores the impact of portion size on mood, an area not typically addressed by standard treatments for mood disorders, which often include medications and therapy. Unlike conventional approaches that focus on chemical imbalances or cognitive patterns, this study examines how changing the size of food portions might directly affect emotional well-being. By comparing decreased, mixed, and increased portion sizes, the trial could uncover a simple, everyday method to influence mood positively, offering a potential new strategy that is both non-invasive and easily integrated into daily life.

What evidence suggests that this trial's treatments could be effective for mood?

This trial will compare the effects of different portion sizes on mood. Participants will join one of the following groups: decreased portion sizes, increased portion sizes, mixed portion sizes, or a control group receiving equal amounts of food.

Research has shown that eating smaller portions can improve mood. In one study with 111 people, those who ate smaller meals consumed less energy, which was linked to better emotional well-being. Other studies suggest that smaller portions can help manage emotional reactions to food, leading to a more positive mood overall.

Regarding larger portions, research highlights a connection between food and mood through the gut-brain link. However, the focus often lies on diet quality rather than just the amount of food when considering mood effects. A review of several studies found that improving diet quality can help reduce symptoms of depression and anxiety, indicating the importance of food type.

Studies on mixed portion sizes have examined their potential impact on mood changes. Some findings suggest that portion size can influence emotional responses to food. However, the effect of mixed portion sizes on mood remains less clear and may vary from person to person. ^{1 3 6 7 8}

Who Is on the Research Team?

Hollie Raynor, PhD

Principal Investigator

University of Tennessee

Are You a Good Fit for This Trial?

This trial is for individuals aged 18-35 with a healthy body weight (BMI of 18.5 to 24.9), who eat without restrictions (score below 12 on the Three Factor Eating Questionnaire) and do not smoke.

Inclusion Criteria

be an unrestrained eater( scoring less than 12 on the Three Factor Eating Questionnaire)

have a body mass index of 18.5 and 24.9 kg/m^2

Report Being a non-smoker

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Treatment

Participants receive different portion sizes of foods to assess mood changes

1 year

Multiple sessions (in-person)

Follow-up

Participants are monitored for safety and effectiveness after treatment

4 weeks

What Are the Treatments Tested in This Trial?

Interventions

• Control
• Decrease Portion Size
• Increase Portion Size
• Mixed Portions

Trial Overview The study explores how different food portion sizes affect mood. Participants will be randomly assigned to control, decreased, increased, or mixed portion size groups to see if there's any impact on their emotional state.

How Is the Trial Designed?

Group I: Mixed Portion Sizes Experimental Treatment 1 Intervention

Participants will receive mixed portion sizes.

Group II: Increase Portion Size Experimental Treatment 1 Intervention

Participants will receive increased portion sizes.

Group III: Decrease Portion Sizes Experimental Treatment 1 Intervention

Participants will receive decreased portion sizes.

Group IV: Control Experimental Treatment 1 Intervention

Participants will receive equal amounts of foods.

Who Is Running the Clinical Trial?

The University of Tennessee, Knoxville

Lead Sponsor

Trials

93

Recruited

19,500+

Published Research Related to This Trial

In a study involving 111 adult participants, reducing meal portion sizes consistently led to decreased energy intake, suggesting that smaller portions can help most people eat less during meals.

The research found no significant participant characteristics (like sex, body weight, or eating behaviors) that affected how much energy intake changed with portion size reduction, indicating that portion control could be an effective strategy for reducing overall energy consumption across diverse populations.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Individual differences and moderating participant characteristics in the effect of reducing portion size on meal energy intake: Pooled analysis of three randomized controlled trials. Robinson, E., Haynes, A.[2023]

The review identified several critical factors that influence the placebo response and clinical trial outcomes in depression, including the probability of receiving a placebo, study duration, dosing schedule, and the severity of the illness.

Understanding these factors can help optimize clinical trial designs for mood disorders, potentially leading to more predictable outcomes and improved success rates in testing new treatments.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The nature of placebo response in clinical studies of major depressive disorder. Papakostas, GI., Østergaard, SD., Iovieno, N.[2022]

Reducing breakfast portion sizes by 20% and 40% did not significantly change overall energy intake throughout the day in a study of 33 adults, indicating that smaller portions may not lead to lower total calorie consumption.

However, a 40% reduction in portion size resulted in lower levels of gastrointestinal hormones associated with fullness and higher appetite ratings, suggesting that while energy intake remained stable, appetite and hormone responses were affected, which could inform strategies for managing energy intake.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Effect of reducing portion size at a compulsory meal on later energy intake, gut hormones, and appetite in overweight adults. Lewis, HB., Ahern, AL., Solis-Trapala, I., et al.[2023]

In a study of 1017 patients with major depressive disorder treated with placebo, key predictors for remission included younger age, less severe depressive symptoms, lower anxiety levels, and shorter duration of the current depressive episode.

The predictive models developed showed modest accuracy (ROC curve areas of 0.6-0.65), suggesting they may help adjust for placebo effects in clinical trials, but are not reliable for predicting remission in individual patients.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Predictors of remission with placebo using an integrated study database from patients with major depressive disorder. Nelson, JC., Zhang, Q., Deberdt, W., et al.[2015]

Citations

1. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC3734152/

A qualitative study of psychological, social and behavioral ... This present study aimed to explore consumers' views about factors influencing their portion size selection and consumption and to identify barriers to ...

2. sciencedirect.com sciencedirect.com/science/article/pii/S0950329322000131

Does portion size matter? Dynamic changes in hedonic ... This study investigated dynamic changes in hedonic and emotional responses to high energy-dense foods varying in portion size.

3. bmj.com bmj.com/content/369/bmj.m2382

Food and mood: how do diet and nutrition affect mental ... Poor nutrition may be a causal factor in the experience of low mood, and improving diet may help to protect not only the physical health but also the mental ...

4. researchgate.net researchgate.net/publication/358023405_Does_portion_size_matter_Dynamic_changes_in_hedonic_and_emotional_responses_to_foods_varying_in_portion_size

Does portion size matter? Dynamic changes in hedonic ... PDF | One way to promote healthier eating behaviors is to reduce food portion sizes and thereby decrease the average daily energy consumed.

5. withpower.com withpower.com/trial/phase-9-2012-0f4a5

Portion Size Effects on Mood · Info for Participants In a study involving 111 adult participants, reducing meal portion sizes consistently led to decreased energy intake, suggesting that smaller portions can help ...

6. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC10490081/

Influence of Food Type on Human Psychological–Behavioral ... Studies show that wholesome meals can increase happiness and well-being, while unhealthy foods may have a weaker mood-elevating effect. Healthy eating can ...

7. ifst.org ifst.org/resources/information-statements/psychology-food-intake-and-portion-control-0

The Psychology of Food Intake and Portion Control Emotions influence both increased and decreased food intake. Depression and stress can inhibit eating, but for some consumers, eating is a comfort and intake is ...

8. sciencedirect.com sciencedirect.com/science/article/pii/S2475299125029142

Beyond Hunger: Uncovering the Link between Food ... This study examines the associations between FI and symptoms of depression, anxiety, and stress in a sample of 712 adolescents aged 12–17 y from Valle de ...