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

25 Participants Needed

Trial Summary

What is the purpose of this trial?

The purpose of this study is to investigate whether different portion sizes will effect overall mood.

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.

What data supports the effectiveness of the treatment 'Decrease Portion Size' on mood?

Research shows that reducing portion size can decrease the amount of energy consumed during a meal for most people, which might indirectly influence mood by preventing overeating and its associated discomfort. ^{1 2 3 4 5}

Is it safe to participate in a clinical trial studying the effects of portion size on mood?

Research on portion size effects, including studies on reducing portion sizes, generally shows no safety concerns for humans. These studies focus on energy intake and appetite, and do not report any harmful effects from changing portion sizes. ^{1 4 6 7 8}

How does the placebo treatment differ from other treatments for mood conditions?

The placebo treatment is unique because it doesn't involve active medication but can still influence mood through psychological and neurobiological responses, such as enhanced patient expectations and the relationship with healthcare providers. This effect is not fixed and can vary greatly, making it different from standard treatments that rely on specific active ingredients. ^{9 10 11 12 13}

Research Team

Hollie Raynor, PhD

Principal Investigator

University of Tennessee

Eligibility Criteria

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

I am between 18 and 35 years old.

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

Timeline

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

Treatment Details

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.

Participant Groups

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+

Findings from Research

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]

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]

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]

References

1. Switzerland pubmed.ncbi.nlm.nih.gov

Effects of Placebo Interventions on Subjective and Objective Markers of Appetite-A Randomized Controlled Trial. [2023]

2. Switzerland pubmed.ncbi.nlm.nih.gov

Taking Placebos as Needed to Reduce Appetite: A Randomized Controlled Trial with Ecological Momentary Assessment. [2023]

3. Germany pubmed.ncbi.nlm.nih.gov

Effect of the perception of breakfast consumption on subsequent appetite and energy intake in healthy males. [2022]

4. England 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. [2023]

5. England pubmed.ncbi.nlm.nih.gov

The effect of a dietary preload on estimation of usual food portion size by photograph in female volunteers. [2004]

6. Switzerland pubmed.ncbi.nlm.nih.gov

Food-Evoked Emotions and Optimal Portion Sizes of Meat and Vegetables for Men and Women across Five Familiar Dutch Meals: An Online Study. [2023]

7. United States 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. [2023]

8. England pubmed.ncbi.nlm.nih.gov

How to measure mood in nutrition research. [2015]

9. Germany pubmed.ncbi.nlm.nih.gov

Pretreatment neurophysiological and clinical characteristics of placebo responders in treatment trials for major depression. [2018]

10. England pubmed.ncbi.nlm.nih.gov

Predictors of remission with placebo using an integrated study database from patients with major depressive disorder. [2015]

11. Germany pubmed.ncbi.nlm.nih.gov

[Clinical significance of the placebo effect]. [2021]

12. England pubmed.ncbi.nlm.nih.gov

The impact of pharmaceutical form and simulated side effects in an open-label-placebo RCT for improving psychological distress in highly stressed students. [2023]

13. United States pubmed.ncbi.nlm.nih.gov

The nature of placebo response in clinical studies of major depressive disorder. [2022]