 Research has shown that body composition is a key component of health and future disease risk. Being overweight and obese is associated with a higher body fat composition, and a greater risk of developing type II diabetes and heart disease. The location where fat is stored in the body is becoming increasingly recognised an important predictor of risk, with extra fat around the abdomen and waist referred to as the android pattern of fat distribution or apple shape thought to increase your disease risk than storing fat around the thighs and buttocks gynoid pattern of fat distribution or pear shape. As a result, there is significant interest in techniques to accurately monitor and detect changes in body composition, and also physiological and lifestyle factors which influence body fat, lean tissue mass and bone mineral density. This cross sectional human study will look at how physiological, behavioural and genetic factors relate to total body composition in 1,196 healthy men and women aged between 18 and 70 years. Interested applicants will be invited to attend for a single visit at the Hugh Sinclair Unit of Human Nutrition at the University of Reading. This visit lasts around two hours and includes noninvasive measures of body composition bio-electrical impedance and dual energy x-ray absorptiometry, arterial stiffness and fasting measures of metabolic health. Diet and physical activity will then be monitored over a four day period using diet and activity diaries, and an activity monitor. The findings from this study will contribute to the evidence base on how subject characteristics influence body composition and inform on the design of future human studies on body composition methodology. 