The GlasVEGAS Study (Glasgow Visceral & Ectopic Fat With Weight Gain in South AsianS) - Does Adipose Tissue Expandibility Differ Between South Asians and Europeans and Does This Contribute to Differences in Cardio-metabolic Disease Risk?

South Asians have about five times the risk of adult onset diabetes (high blood sugar) than Europeans and nearly one in five South Asian men in the United Kingdom have the disease. Diabetes is a serious disease that can lead to a number of adverse health consequences including heart disease, kidney disease and blindness and accounts for about 10% of all healthcare costs in the UK. Obesity is strongly linked to diabetes risk, but the adverse effect of getting fatter on diabetes risk is much higher in South Asians than Europeans. The purpose of this study is to understand why this is the case. When humans put on weight initially this fat is stored under the skin (subcutaneous fat). This is relatively safe. However, when the capacity of this under skin storage is exceeded, fat is stored internally within the tummy area (visceral fat) and in organs such as the liver and muscle, which is less safe and increases diabetes risk. Investigators think that South Asians' capacity to store fat safely under the skin is lower than Europeans, so fat is stored internally and in liver and muscle at lower body weights than Europeans. The purpose of this study is to investigate whether this occurs and why. To do this investigators will compare a group of South Asian and European men and see how gaining and losing weight affects fat storage within the body and the function of fat cells. Investigators will also assess the effect of weight gain and weight loss on metabolism, fitness and risk factors for diabetes and heart disease.

The study will include healthy men of normal weight aged between 18-45 year and of either white European or South Asian (both parent of Indian, Pakistani, Bangladesh or Sri Lankan origin) ethnic origin.

Body weight will be altered by initially gaining weight and then losing weight. To do this participants will initially have to eat more food for 4-6 weeks and then go on a diet combined with exercise for 12 weeks. Participation in the study will last around 5½ months in total.

During the study pictures of body fat stores will be taken using an MRI scanner, a biopsy/sample of tummy fat will be taken to look at the fat cells and physical fitness and body metabolism (the way the body deals with sugar, insulin and fat) will be measured. These measurements will be done at three different times: before gaining weight, once weight is gained, and after losing weight (and back to original weight). The measurements will give a detailed assessment of the changes in the body when gaining or losing weight.

The benefits of taking part in the study are receiving detailed feedback about fitness levels, body fat, dietary intake, blood pressure, cholesterol, blood sugar and level of "insulin resistance". Feedback about the overall study findings will also be provided.