Weight loss and premature death: the 1946 British birth cohort study

Abstract

Objective: The relationship between weight loss and mortality has important clinical and public health significance but has proved to be complex. Evidence is mixed and particularly limited on the association between weight loss in mid-life and premature death (i.e. before 65 years of age), a small albeit important segment of total mortality. We aimed to study the association between midlife weight change and mortality accounting for health and lifestyle characteristics, and also considering potential bias due to preexisting chronic diseases and smoking status.

Design: Longitudinal, population-based, 'the 1946 British' birth cohort study.

Subjects and measures: In 2750 men and women, mortality from age 53 through 65 years was analyzed according to categories of measured 10 year weight change between 43 and 53 years. Cox's hazard ratios (HR) were progressively adjusted for socio-demographic, lifestyle and health characteristics.

Results: Nearly 20% of participants lost weight and over 50% gained 5 kg or more in midlife. There were 164 deaths. Compared to those who gained between 2 and 5 kg, those who lost 5 kg or more had an increased risk of premature death independently of midlife physical activity, socio-economic circumstances and educational attainment. This association was unaltered when highest weight loss (lost more than 15 Kg) (p = 0.04) and early deaths were excluded (p<0.001), but was no longer significant after adjustment for cardiovascular risk factors and health status (HR = 1.8; 95% CI: 0.9 to 3.5).

Conclusion: The inverse association between weight loss in midlife and higher risk of premature death may be explained by vascular risk factors and ill health. In consideration of the burden of premature death, closer monitoring of weight loss in mid-life is warranted.

Figure 1. Weight Change (kg) Between 43 and 53 Years and all-Cause Mortality Hazard Ratios (HRs) Between 53 and 65 Years (95% CI bands, dotted lines), in the 1946 British Birth Cohort (n = 2 568; deaths  = 141).

HRs are from Fully Adjusted* Cox Regression Using Cubic Splines and Median Weight Change ( = 4.8 Kg) as Reference Point.