Whole Foods for Teens: A Pilot Dietary Intervention to Reduce Body Adiposity in Adolescents With Obesity

This study will address the following aims:

Aim 1: Conduct an 8-week pilot RCT to examine the effects of a whole foods diet intervention on body adiposity in adolescents with obesity.

Aim 1a (Primary): Evaluate intervention effectiveness on total fat mass following the 8-week intervention.

Hypothesis 1a: Adolescents randomized to the whole foods intervention will have lower total fat mass (kg) at the 8-week follow-up than those in the control group.

Aim 1b: Evaluate intervention effectiveness on anthropometric changes following the 8-week intervention.

Hypothesis 1b: Adolescents randomized to the whole foods intervention will have lower weight, BMI-z scores and/or waist circumference at the 8-week follow-up than those in the control group.

Secondary Aims:

Aim 2: Conduct an 8-week pilot RCT to examine the effects of a whole foods diet intervention on diet quality in adolescent and parent pairs during the study period.

Hypothesis 2: Adolescents and parents randomized to the whole foods intervention will have higher diet quality scores at the 8-week follow-up than those in the control group.

Aim 3: Conduct post-intervention family focus groups to identify how individual/family needs and preferences and social determinants of health (SDOH) may be perceived barriers and/or facilitators of diet adherence to a whole foods diet pattern.

For adolescents with obesity, a healthy diet pattern is recommended as a first-line non-pharmacological treatment. Yet, despite decades of research, there is inconclusive evidence from randomized clinical trials (RCT) to support an optimal dietary pattern to treat adolescent obesity. While observational data has linked poor-quality diet patterns high in calories, fat, and refined carbohydrates to greater body adiposity in adolescents, some research suggests that dietary patterns that emphasize high-quality whole foods (e.g. Mediterranean, low-glycemic load) not only improve diet quality but can also effectively reduce body adiposity and improve metabolic outcomes (e.g., insulin resistance) without the need for calorie restrictions. However, for adolescents with obesity, adherence to a healthy diet pattern requires the involvement of the whole family, with the potential to improve diet quality and reduce body adiposity and its associated metabolic complications. Unfortunately, weaknesses of past studies include 1) a failure to intervene upon diet quality at the family level to modify adolescent dietary behaviors, and 2) a lack of consideration for how individual/family needs and social determinants of health (SDOH) impact diet adoption. To address these gaps, we will test a novel 8-week pilot RCT of a non-calorie-restricted whole foods diet adapted from the 2020-2025 Dietary Guidelines for Americans that offers a simple, customizable MyPlate Plan approach (i.e., 5 daily food group goals) focused on individual, family, cultural, and budgetary preferences. We will recruit 30 eligible adolescent (10-18 years) and parent (≥25 years) pairs to test the diet's effects on 1) adolescent body adiposity measured with dual-energy x-ray absorptiometry (DXA) to measure fat mass and anthropometry to measure weight, BMI, and waist circumference (Aim 1) and 2) adolescent and parent diet quality scores measured from dietary recalls using the 2020 Healthy Eating Index during the intervention (Aim 2). Post-intervention family focus groups will be conducted to understand how individual/family needs and preferences and SDOH may be perceived barriers or facilitators of diet adherence in families (Aim 3). Feasibility, acceptability, enrollment, retention, and diet satisfaction data will be generated to establish successful benchmarks to support future studies. Participants randomized to the intervention will receive bi- weekly food delivery, menus, and dietetic support for 8 weeks. Participants randomized to the usual care group will receive a single dietetic counseling session on MyPlate. The successful completion of this study will result in the generation of quantitative and qualitative data to support a future R01 that will test the long-term effectiveness of a whole foods diet on obesity and metabolic outcomes, and diet sustainability in adolescents with obesity and their families.

Eligibility Criteria:
Inclusion Criteria:

For this study, eligible adolescents will be those that:

1. 10-18 years of age at time of initial screening;
2. living at home full-time with the enrolled parent or caregiver (≥80% in primary residence);
3. obesity defined as a body mass index (BMI) greater than or equal to 95th percentile for age and gender based on standardized CDC growth curves;
4. reside within greater Middle Tennessee area and has enrolled parent/caregiver willing to drive to Vanderbilt University and Vanderbilt University Medical Center for study visits;
5. are without medical conditions that would limit participation in a diet-related study (e.g., tube feeding, dysphagia, severe food allergy to 3 or more food groups causing anaphylaxis);
6. are willing and able to participate in an 8-week diet study that encourages preparing and eating healthy foods and snacks for 8 weeks with parental or caregiver support;
7. have parental or caregiver commitment to participate in the research study;

For this study, eligible adult parents or caregivers will be those that:

1. adult parent or primary legal caregiver (greater than or equal to 25 years of age) of an enrolled adolescent;
2. live with the adolescent full-time (≥80% in primary residence);
3. have 1 or more metabolic risk factor(s) and/or metabolic condition(s) (e.g., overweight/obesity, hypertension, hypercholesterolemia or dyslipidemia, hyperglycemia \[elevated fasting blood glucose ≥100 mg/dL\] and/or prediabetes, history of gestational diabetes, polycystic ovarian syndrome, type 2 diabetes, non-alcoholic fatty liver disease);
4. reside within greater Middle Tennessee area and are willing to drive to Vanderbilt University and Vanderbilt University Medical Center for study visits;
5. are without medical conditions that would limit participation in a diet-related study (e.g., tube feeding, dysphagia, severe food allergy to 3 or more food groups);
6. are able to participate in a study program that encourages preparing and eating healthy foods and snacks for 8 weeks with most preparation/cooking of meals/snacks at home;

Exclusion Criteria:

Adolescent exclusion criteria include:

1. Outside of the specified age range;
2. not living in the home of the enrolled parent or caregiver full time (≥80% in primary residence);
3. BMI less than 95th percentile for age and gender;
4. pregnant or lactating;
5. no eligible enrolled parent or caregiver or lack of parental/caregiver commitment to participate in study;
6. food allergy to 3 or more food groups; dietary restrictions or medical condition that prohibits participation in a diet study;
7. use of medications that cause weight loss or diabetes medications;
8. active participation in a weight loss or intense lifestyle modification program;
9. limited English-language proficiency;
10. participants unwilling or unable to give informed consent, accept random assignment, attend dietary counseling sessions, adhere to treatment prescription, or complete study measures;
11. adolescents who display dissenting behaviors during baseline data collection;
12. adolescents who do not otherwise meet the eligibility criteria listed in sections above as determined by pre-screen;

Adult Parent or Caregiver exclusion criteria include:

1. not parent/ or legal caregiver;
2. not living in a household full-time with enrolled adolescent (less than 80% time spent away from primary residence);
3. lack of metabolic condition(s) per inclusion criteria;
4. special dietary restrictions, food allergies, or medical conditions that prohibit participation in a diet-related study;
5. limited English-language proficiency;
6. participants unwilling or unable to give informed consent, accept random assignment, attend dietary counseling sessions, adhere to treatment prescription, or complete study measures;
7. parent or caregivers who do not otherwise meet the eligibility criteria listed in sections above as determined by pre-screen;