Outcome
Type |
Measure |
Description |
Time frame |
Safety issue |
Other |
Change in executive function from baseline to 2-weeks post high UPF or 2 weeks no UPF diet |
Participants will undergo computerized tests of executive function, such as working memory, cognitive flexibility, and inhibitory control. These tasks have been widely used with participants across the lifespan and contain simple graphics. |
4 measurements (pre/post 2-week UPF diet, pre/ post 2-week no UPF diet) |
|
Other |
Change in eating in the absence of hunger from baseline to 2-weeks post high UPF or 2 weeks no UPF diet |
Following the ad libitum buffet meal, participants will move to a separate room where an ample amount of 4 pre-weighed snack items (2 UPF, 2 no UPF) and magazines are available. Using an approach consistent with previous research studying this outcome, participants will be instructed to take 2 bites of each snack item and rate its palatability on the LHS, and to eat the remainder of the snacks or look at the magazines while they wait for the next part of the study. Participants will be left to consume the snacks or relax for 15 minutes. Participants will also be given a box of snacks to assess eating in the absence of hunger outside the laboratory environment. Snack boxes will be returned to study staff the next morning. Staff will document the amount and type of snacks consumed. |
4 measurements (in person and take home portion following the 2-week UPF diet, in person and take home portion following the 2-week no UPF diet) |
|
Other |
Change in internal state ratings from 2 weeks high UPF or 2 weeks no UPF diet |
To assess sensations of hunger a Visual Analog Scale bounded by "not hungry at all" and "extremely hungry" will be used. With higher scores indicated higher hunger. Same for fullness. Visual Analog Scales will be completed prior to (min. 0), and following the buffet meal (min. 30). |
2 measurements (following the 2-week UPF diet, following the 2-week no UPF diet) |
|
Other |
Change in sensitivity to delayed consequences from 2 weeks high UPF or 2 weeks no UPF diet |
To assess sensitivity to delayed consequences by assessing preference for different amounts of money varying over different amounts of time. This will be associated with a k value (discount rate), the lower the k value, the less discounting. |
4 measurements (pre/post 2-week UPF diet, pre/ post 2-week no UPF diet) |
|
Primary |
Change in brain response from baseline to 2-weeks post high UPF or 2 weeks no UPF diet |
3 hours post supervised breakfast, participants will rate each flavored milkshake and a tasteless solution in the scanner before image acquisition using an fMRI compatible mouse. Two flavors of ultra-processed milkshake will be used to avoid flavor habituation during the scan. An artificial saliva or "tasteless" solution is used as a control condition. Each milkshake and tasteless solution will be delivered through a custom manifold fitted to the head coil and connected to a pump system that allows precisely timed and measured delivery of liquids. Two 11-minute scans will be performed, where both milkshakes and the control tasteless solution will be delivered using an event-related design over 4 seconds. A variable "jitter" of 5-12 seconds will follow stimulus delivery, allowing time to swallow. Following each milkshake or tasteless presentation, a water rinse will occur over 4 sec to clear any remaining solution from the mouth. fMRI testing will take place before and on day 14. |
4 measurements (pre/post 2-week UPF diet, pre/ post 2-week no UPF diet) |
|
Secondary |
Change in energy intake from 2 weeks high UPF or 2 weeks no UPF diet |
Participants will arrive at the laboratory in the fasted state for an ad libitum breakfast buffet meal. The buffet meal will contain a variety of food items that vary in macronutrient content and in their degree of processing (UPF, no UPF). The meal will consist of typical breakfast items in excess of what would normally be consumed. Participants will self-select foods over a 30-minute period. Food items will be weighed (±0.1 grams) prior to and after the completion of the meal to determine the amount consumed (g, kcal), calculated using NDSR nutritional analysis software. |
2 measurements following the 2-week UPF diet (day 15), following the 2-week no UPF diet (day 15) |
|
Secondary |
Change in eating rate from 2 weeks high UPF or 2 weeks no UPF diet |
Participants will arrive at the laboratory in the fasted state for an ad libitum breakfast buffet meal. The buffet meal will contain a variety of food items that vary in macronutrient content and in their degree of processing (UPF, no UPF). The meal will consist of typical breakfast items in excess of what would normally be consumed. Participants will self-select foods over a 30-minute period. Meal eating rate (g/min, kcal/min) will be determined using meal start and stop times. |
2 measurements following the 2-week UPF diet (day 15), following the 2-week no UPF diet (day 15) |
|
Secondary |
Change in food items selected from 2 weeks high UPF or 2 weeks no UPF diet |
At the ad libitum buffet meal, food selection will be determined by the number of items consumed from UPF vs no UPF. |
2 measurements (following the 2-week UPF diet, following the 2-week no UPF diet) |
|
Secondary |
Change in grams of food selected from 2 weeks high UPF or 2 weeks no UPF diet |
At the ad libitum buffet meal, food selection will be determined by the number of grams consumed from UPF vs no UPF. |
2 measurements (following the 2-week UPF diet, following the 2-week no UPF diet) |
|
Secondary |
Change in amount of energy (kcals) selected from 2 weeks high UPF or 2 weeks no UPF diet |
At the ad libitum buffet meal, food selection will be determined by the number of amount of energy (kcals) consumed from UPF vs no UPF. |
2 measurements (following the 2-week UPF diet, following the 2-week no UPF diet) |
|