Ectopic Fat in Singaporean Women - the Culprit Leading to Gestational Diabetes, Metabolic Syndrome, and Type 2 Diabetes (TANGO Study)

Overview

Ectopic fat is the accumulation of adipose tissue in anatomical sites not classically associated with fat storage - for example, in the liver and skeletal muscles. Excessive fat accumulation in liver cells, often diagnosed as non-alcoholic fatty liver disease (NAFLD), is a precursor to a wide range of liver conditions and metabolic disorders. The usual standard of care for NAFLD is to advise weight loss through controlled diet and physical activity, but the outcome of weight management and treatment of NAFLD is highly variable. Diet interventions - such as the Mediterranean, ketogenic, paleo, and high-protein-low-carbohydrate diets - have shown varied benefits in the management of NAFLD. However, food-based interventions must align with cultural and regional preferences in food to succeed in making the modifications part of the habitual diet. A recent diet intervention study (Della Pepa et al., 2020) highlighted that the components of a diet, rather than its caloric content, play a greater role in achieving healthier outcomes. In this study, a multifactorial diet intervention using locally sourced and produced meals will be implemented with the aim of reducing elevated liver fat content in healthy women diagnosed with NAFLD. The study will also evaluate the effects of the proposed diet on the participants' metabolic health and describe potential changes in their gut microbiome signatures (via frequent stool samples). The dysregulation of the gut microbiota has been linked to the development of NAFLD and it is known that the composition of the gut microbiota could be modified by dietary intake. This study will investigate the association of gut microbiome signatures with elevated liver fat in Asian women and test whether the dietary intervention will modify their gut microbiota. Finally, ectopic fat in the liver is a highly prevalent condition worldwide but the cut-off values for NAFLD has been largely derived from studies performed in Western populations. This study seeks to cross examine the diagnostic ranges in various clinical assessments of NAFLD that commonly involve ultrasound spectroscopy (Fibroscan), fatty liver indexes (FLI) and magnetic resonance spectroscopy (MRS). This effort seeks to derive appropriate cut-off values for NAFLD in Singaporean-Chinese women.

The study will consist of a 12-week, parallel three-arm, single-centre, randomized controlled trial (RCT); 90 women of Chinese ethnicity matched for age and BMI will be randomized to one of 3 study arms in 1:1:1 ratio by Blockrand R software at Week -1 visit. The study arms are: (1) Lifestyle advice alone, (2) Lifestyle advice with calorie-restricted diet-intervention, and (3) Lifestyle advice with calorie-restricted diet-intervention inclusive of odd-chain fatty acids (OCFA)-containing food product. In all 3 study arms, the lifestyle advice on maintaining a healthy diet and regular exercise (\~180 mins/ week) will be compatible with recommendations by Health Promotion Board. The participants in the control study arm (Lifestyle advice alone) will receive 1 session of diet advice from the study dietician at the start of the study only. The dietitian will provide dietary advice on the eating plans and instructions for completion of diet checklist. In the "Diet Intervention (calorie-restricted multifactorial diet)" study arm (arm 2), a moderate energy restriction (500-1000 kcal/day) will be prescribed to facilitate weight loss. To facilitate compliance, participants in the diet-intervention arms will receive individual diet consultations with the study dietitian during the study. Participants in both the meal-based diet-intervention arms (arm 2 and arm 3) will be supplied with 2 main meals per day as part of their daily diet, for 6 days a week. Additional food products may be supplied for breakfast and snacks. The diet will be designed to be nutritionally replete, feasible, and sustainable in the long-term. The diet will be based on whole grain-based products, vegetables, legumes, extra virgin olive oil, fruits, almonds, salmon, and plant-based meat analogues. Diet plans will be individualized and energy matched to enable any metabolic differences between arms to be attributed to the macronutrient profiles of the diets, without confounding by differences in weight loss between diet arms. Energy requirements will be calculated by indirect calorimetry (Quark CPET, COSMED) with an activity factor. Participants in the "OCFA meal-based diet-intervention" study arm (arm 3) will be provided with a daily OCFA-containing food product, in addition to the lunch and dinner meals. Both the participants in arm 2 and 3 will be receiving the same lunch and dinner meals. Participants in both the meal-based diet-intervention arms (arm 2 and arm 3) will be told to consume only low-fat dairy products (milk, yoghurt), avoid ruminant meat (beef, lamb), avoid cheese, butter and butter-containing food products. Both diet-intervention arms will be told to avoid sugar-sweetened beverages.