Ultra Crave: An Investigation of Ultra-Processed Food

This study experimentally investigates whether a reduction in ultra-processed (UP) food intake (1) causes aversive withdrawal symptoms in humans, (2) increases the motivational salience of UP food cues and, if so, (3) whether these factors undermine the ability to adhere to a low-UP diet. The following aims and hypotheses are tested:

Aim 1: To investigate whether aversive physical, cognitive, and affective withdrawal symptoms emerge in response to reduced UP food intake compared to a high-UP diet, and whether this predicts failure to adhere to a low-UP diet.

H1a: Reducing UP food intake will result in aversive physical, cognitive, and affective withdrawal symptoms, as indicated by 1) ecological momentary assessment (EMA) reports of aversive withdrawal symptoms, and 2) heart rate reactivity and subjective distress to an in-lab stressor.

H1b: Aversive symptoms of UP food withdrawal will predict greater UP food intake and higher blood glucose levels when trying to adhere to a low UP diet.

Aim 2: To investigate whether increased motivational salience of UP food cues emerges in response to reduced UP food intake, and whether this predicts failure to maintain a low-UP diet.

H2a: Reducing UP food intake will result in increased motivational salience of UP food cues, as indicated by 1) EMA reports of UP food craving, 2) heart rate reactivity and subjective craving in a simulated fast-food restaurant, 3) heightened reinforcement value for UP food relative to other reinforcers, and 4) greater reward-related neural response to UP food cues.

H2b: Increased motivational salience of UP food cues will predict greater UP food intake and higher blood glucose levels when trying to adhere to a low UP diet.

The study will include a combination of in-person, at-home, and virtual activities over the course of \~14 days (contingent on scheduling, this duration may vary and particularly between in-person visits #1 and #2). Participants complete three in-lab visits. Visit 1 and 2 will each followed by a week of remote data tasks (e.g., EMA, continuous glucose monitoring, physical activity and sleep tracking (Fitbit), and two 24-hour dietary recall interviews).

During in-lab visit #1, participants will complete questionnaires, behavioral tasks, and interviews, and will have body composition measurements taken (height, weight, Inbody scan). Participants will complete the remote tasks for the following week while eating their typical diet (i.e., baseline period).

During in-lab visit #2, participants will complete questionnaires, interviews, and body composition measurements (height, weight, Inbody scan). Participants are randomly assigned to one of three conditions--control (i.e., high UP), self-guided low UP, or meals provided low UP--and will follow instructions about how to eat consistent with their condition during week 2 of remote data collection (i.e., dietary intervention period).

During in-lab visit #3, participants will complete questionnaires, behavioral tasks, body composition measurements (height, weight, InBody scan), and an fMRI scan.

Participants are contacted 1- and 3-months later to complete a short follow-up survey and provide information about their current diet.

Eligibility Criteria:
Inclusion Criteria:

* 22 to 60 years of age
* English-speaking
* Must own an Android or iPhone Smartphone
* Live within a 1-hour radius of the laboratory
* endorsement of \> 4 symptoms on the YFAS 2.0 completed during eligibility screener; at the time of consent, symptom count must remain above threshold for food addiction (this discrepany is based on a previously found tendency during pilot testing to overestimate food addiction symptoms at the time of screening)
* Willing and able to follow specific dietary instructions provided by the study team
* Willing and able to attend 3 in-person lab visits
* Willing to complete 4 phone interviews about foods eaten in the past 24 hours
* Willing to report daily intake of food
* Like the taste of chocolate milkshake (for fMRI scan eligibility only).

Exclusion Criteria:

* participants with a self-reported BMI \< 18.5 and \> 40
* Current diagnosis of disorder that may impact study results or the ability to safely complete study tasks (hypothyroidism (uncontrolled by medication), diabetes, etc.)
* History of food allergies
* Unable to respond to brief questionnaires within 90-minutes during the day
* Work night shifts or irregular shifts
* Restrictive dietary requirements (e.g., vegan) or high levels of picky eating
* Medications (e.g., insulin, antipsychotic medications) that may impact study results or safe completion of study tasks
* Diagnosis of severe mental illness (e.g., schizophrenia, bipolar disorder)
* Diagnosis of a restrictive eating disorder (e.g., Anorexia Nervosa, Bulimia Nervosa, purging disorder) within the last 5 years
* Current diagnoses of disorders that can impact reward/metabolic functioning
* 20+ pound weight fluctuation in the last 3-months
* Prior weight loss surgery (e.g., bariatric surgery)
* Currently pregnant, breastfeeding, trying to get pregnant, or within 6-months of having given birth
* High levels or high-risk intake of alcohol or caffeine
* Use of tobacco or nicotine in the past month
* Use of THC cannabis within the past week
* Unwillingness to abstain from THC cannabis, tobacco or nicotine during the main portion of the study (\~22 days)
* fMRI contraindications (e.g., claustrophobia, metal implants).
* inability to complete a random report within 90 minutes