Portion Size Effects on Body Weight:Free Living Setting

Study Overview
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Brief Summary
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The study purpose was to evaluate the effects of portion sizes on body weight and energy intake in a free-living setting. 223 healthy adults were recruited from an urban worksite and randomized to one of four groups for a six-month period. The groups were: 1) 400 kcal box lunch; 2) 800 kcal box lunch; 3) 1600 kcal box lunch; or 4) no box lunch. Participants were required to pick up a box lunch every week day for six months. Control participants did not receive a box lunch and were instructed to eat their usual lunch. Participants were weighed and dietary intake measured at baseline, one, three and six months. It was hypothesized that at six months, participants in the 1600 kcal box lunch would gain more weight and have higher energy intake than those in the other groups.

Official Title
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Portion Size Effects on Body Weight: Free Living Setting

Conditions
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Portion Sizes

Intervention / Treatment
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* Other: portion size kcal of box lunch


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: : 1) age 18-60 yrs; 2) nonsmoker; 3) fluent in English; 4) not taking medications that affect appetite or body weight; 5) work at the medical complex full time, including during the lunch hours; 6) not allergic to the foods in the study lunches; 7) willing to eat the foods in the study lunches [examples were provided of the types of foods]; 8) not currently on a diet to lose weight; 9) no history of a diagnosed eating disorder; 10) not moving from the area during the next six months; 11) not currently taking part in another research study; 12) not currently pregnant, nursing or pregnant in the last 12 months. Exclusion Criteria: if the person does not meet the criteria above -

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 60 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: portion size small<br>400 kcal box lunch was delivered each weekday to each participant at the worksite for a six month period. | Other: portion size kcal of box lunch<br> <br> * Other names: box lunches of different portion sizes were provided to participants each weekday for six months. Portion size conditions were 440 kcal, 800 kcal or 1600 kcal.;|
| Experimental: portion size medium<br>800 kcal box lunch was delivered each weekday to each participant at the worksite for a six month period. | Other: portion size kcal of box lunch<br> <br> * Other names: box lunches of different portion sizes were provided to participants each weekday for six months. Portion size conditions were 440 kcal, 800 kcal or 1600 kcal.;|
| Experimental: portion size large<br>1600 kcal box lunch was delivered each weekday to each participant at the worksite for a six month period. | Other: portion size kcal of box lunch<br> <br> * Other names: box lunches of different portion sizes were provided to participants each weekday for six months. Portion size conditions were 440 kcal, 800 kcal or 1600 kcal.;|
| No Intervention: control<br>no box lunch provided to participants. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| body weight change | change in body weight from baseline to six months | six months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| dietary energy intake | change in energy intake from baseline to six months | six months |