The Healthy Diet and Lifestyle Study

Background and rationale: East Asian adults are known to have higher levels of visceral adiposity than whites, African Americans, and Hispanic adults in the US. This visceral fat deposition, because of its close proximity to the portal vein, has greater metabolic activity and is associated with a greater risk of cardiometabolic diseases and possibly certain cancers (e.g., breast and colorectal cancers). Newly introduced weight loss interventions, specifically, intermittent energy restriction (IER), have been proposed to be as effective as continuous energy restriction, achieve higher and long-term compliance, and may predominantly result in a decrease in visceral fat. Thus, implementing this novel weight loss intervention among East Asian Americans with high visceral fat deposition would be particularly beneficial .

Goal: This study aims to demonstrate the feasibility to conduct an intermittent energy restriction (IER) nutritional intervention aimed at reducing visceral adiposity in overweight Asian Americans middle-aged adults.

1. To finalize and implement a protocol for an IER intervention plus exercise with the goal of reducing visceral fat in overweight adult East Asian Americans (EAA). The protocol will include an intensive dietary intervention and an exercise program administered by a dietitian through individual meetings and the use of new technologies to monitor dietary compliance.
2. After eligibility screening, 70 individuals will be randomized to either the intensive intervention diet group or to a non-intensive intervention (active comparator) diet group for 12 weeks. The intensive intervention group will follow a low carbohydrate- low energy IER diet for two consecutive days, and the Mediterranean (MED) diet for the other five days and meet estimated energy requirements (IER + MED group). The active comparator group will follow the Dietary Approaches to Stop Hypertension (DASH) diet for all seven days and meet estimated energy requirements (DASH group). With an expected attrition rate of ~25%, the investigators expect ~50 participants to complete the study.
3. To evaluate study retention, protocol adherence, effect size of the intervention on body weight, total adiposity, DXA measured visceral fat (main outcome), estimated visceral adipose tissue area, and selected clinical measures (e.g., waist circumference, hip circumference).

Design: Randomized lifestyle intervention trial to compare the effects of two twelve-week diets - (i) an IER + MED diet versus (ii) DASH diet- on DXA quantified visceral fat deposition distribution in overweight/obese men and women. Both intervention groups will be asked to follow a moderate exercise program (1 hour of walking five days a week). The research will be carried out in the University of Hawaii Cancer Center (UHCC). The investigators will determine and compare the primary and secondary endpoints at least five days after the last 2 energy-restricted days to a corresponding day of the week in the DASH group at the completion of the 12th week of IER+MED or DASH diets.

Assessing dietary intervention adherence: Dietary intake of energy, fat (monounsaturated fatty acids (MUFA), Polyunsaturated fatty acids (PUFA) and saturated fat), carbohydrate, protein, dietary fiber and alcohol will be assessed prior to the first week of intervention, the 5-6th week, and the 12th week. Participants will capture images of foods eaten and consumed over four days (i.e., before and after images of each eating occasion). A mobile app designed to seamlessly take images of foods/beverages will be loaded to onto each participant's mobile telephones for free and removed at the end of the study. Physical activity level will be assessed at baseline using a physical activity questionnaire.

Advice, support and monitoring in both diet groups Foods eaten for the IER+MED and DASH diets will be self-selected by the participants and not provided by the study team. The IER+MED and DASH groups will receive clear instructions on how to follow the allocated diet in a face-to-face dietary consultation with one of the trial dietitians (45- 60 minute appointment) at the UHCC. Both groups will receive comprehensive written instructions of how to follow the diets at home, including recommended portion sizes and recipes and suggested meal plans. Both groups will receive appropriate behavioral techniques to promote adherence to diets (i.e., self-monitoring of diet and goal setting).

Participants will be contacted by telephone by an allocated dietitian one week after randomization to check that they have started the diet, to assess understanding of the diet and to provide any trouble shooting advice. Participants will be contacted by an allocated dietitian with weekly phone calls in weeks 1 to 4 to discuss adherence and any problems with the diet; and with every other week phone calls in weeks 5 to 12. Both groups will be asked to record 4-day dietary records with the mobile food record at Week 6 and Week 11. This will allow assessment to adherence of the allocated diets and better tailor dietary advice. Participants will be asked to report overall compliance to the diet and physical activity plans using a scale of 0-10 for each, on the weekly and fortnightly phone calls with the dietitian. The IER+MED group will also be asked to record adherence to the 2-day IER using a scale of 0-2. All participants will also be advised to become more active, walking at least one hour per day five days per week. The intermittent energy restriction (IER) group will be encouraged to walk on the non-IER days.

Post-Study At the end of the study all participants will be offered advice on continued weight loss and/or weight loss maintenance if they have reached a target weight and this is appropriate. This will include advice regarding preferred diet, i.e., IER+MED or DASH. If resources permit, the investigators will recontact participants six and twelve months after the end of the intervention to assess dietary intake, physical activity and body weight.

Statistical Considerations Statistical analysis will be conducted within Epidemiology Program, UHCC. The primary aim is to determine changes in percentage visceral fat between the IER+MED diet and the DASH diet over a 3 months period. The sample size of 25 participants per group has been chosen to detect a difference of 15 percentage points in the reduction in visceral fat between the two different diets, assuming an estimated 25% drop-out rate. Calculations assume a two-sided t-test with estimated standard deviation of 10% and the conventional 5% significance level. The primary analysis will be performed on an intent-to-treat principle, where all participants will be analyzed by randomization group, regardless of compliance.

The primary endpoints of visceral fat measurements will be regressed on randomization group and time point, as well as potential confounders, using a mixed model approach accounting for the repeated measures at baseline, and 6 and 12 weeks. The primary hypothesis will be tested by a contrast F test comparing the difference between groups in the change from baseline to 12 weeks. The 6 month assessment will be similarly tested to understand the trend over time. If there is evidence of a linear change in fat over time, time will be entered as a continuous variable and the slope will be compared between groups. Visceral fat will be modelled as an absolute area and as percentage of total area. The secondary analysis will analyze relationship between the IER+MED intervention and total adiposity.

Ethical Considerations The study will be performed in accordance with the ethical principles in the Declaration of Helsinki and the University of Hawaii operational and ethical guidelines for research and other applicable regulatory requirements.

Participant information and consent Consent to enter the study will be sought from each participant only after a full explanation has been given, information has been provided and time allowed for consideration. The right of the participant to refuse to participate without giving reasons will be respected.

Discontinuation and withdrawal Participants are free to withdraw from the study at any time, without prejudice to further treatment. Participants may also be discontinued from the study at any time, at the discretion of the investigator. Requests by the participant to be withdrawn from the study should be made through the principal investigator.

Confidentiality After the participant has consented, any information from the study will be stored on a secure password-protected computer that will be accessible only to the research team. Trial data on anthropometry and activity meter data will be kept in a secure computer at the UHCC. The food \& beverage images from the 4-day mobile food records will be kept on a secure server.

Data Handling and Record Keeping All data will be kept strictly confidential. Any individual volunteering to participate will be assigned a code number, with the link to identifying information only available to the few study staff that require this information. Identifying information will be maintained in separate secure computer files from the remainder of the data. All forms will be stored in locked file cabinets, and those with identifying information will be stored separately from the other forms. No analysis will ever identify participants individually.