Obesity, Body Fat Distribution, and Cancer Risk in the Multiethnic Cohort 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.