A longitudinal study of adolescents into adulthood: tracking of nutrient intake and body size
Cardiovascular disease, cancer and type 2 diabetes are major causes of death and links with obesity and diet are well established. In addition, several of the metabolic consequences of obesity relate specifically to intra-abdominal fat accumulation. Efforts to tackle these problems are now turning towards early prevention rather than later treatment. However, this assumes that improvements in diet and adiposity will be maintained into adulthood. This thesis describes the progression of diet and body fat from adolescence into adulthood by assessing how they change, whether individuals maintain nutrient intake and body size relative to other individuals (or ‘track’), and whether adult intakes and levels of adiposity are influenced by other factors present between adolescence or adulthood. The study followed up, at 33 years old, 202 participants of a survey of Northumberland 12 year olds carried out in 1979-1980. At both time-points dietary intake was measured using two 3-day food diaries with follow up interviews, and height and weight were measured to assess body mass index (BMI, kg/m2). Additional measurements of abdominal body fat (waist circumference) and body fat distribution (waist-to-hip circumference ratio) were taken at 33 years old only. Socio-demographics and lifestyle data were collected. Between 12 and 33 years of age, the prevalence of overweight and obesity escalated dramatically whilst absolute nutrient intakes had moved much closer to the dietary recommendations. Despite this, relative body size, and to a lesser extent nutrient intake, was maintained significantly between 12 and 33 years. BMI at age 12 also predicted the development of obesity and abdominal fat accumulation in adulthood. Adult nutrient intakes and body size were subject other significant factors, particularly gender, smoking status and carbohydrate intake at 12 years old. These findings provide evidence to support initiatives aimed at achieving an optimal nutrient intake and body weight early in life, but emphasise the fact that these measures are subject to other factors occurring beyond early adolescence.
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