Obesity is associated with a range of poor health outcomes (e.g., high blood pressure), but not all obese individuals have these outcomes. The relationships of childhood growth and body mass index (BMI is used to define obesity) trajectories, that describe how BMI changes as a person ages, with adulthood obesity have been well-documented. However, few studies have investigated whether there are multiple different patterns of BMI change over age that all lead to adulthood obesity but have different health outcomes. For example, it has been proposed that there are two main BMI patterns that lead to adulthood obesity. The first is characterised by being big at all ages due to a healthy combination of fat and fat-free mass, while the second is characterised by low or normal BMI in infancy and subsequently an unhealthy level of fat accumulation in childhood. It is hypothesised that the first pattern doesn't incur any adverse health consequences, while the second pattern does. This project aims to test this idea that there exist multiple different BMI patterns that lead to adulthood obesity and that they have different consequences for cardio-metabolic health. The same analysis in normal weight adults will help explain the BMI pattern that leads to some normal weight adults having poor health prospects.