Intentional weight loss and mortality among initially healthy men and women.
ABSTRACT Most prospective observational studies suggest that weight loss increases the risk of premature death among obese individuals. This is surprising because clinical studies show that weight loss generally leads to overall improvements in cardiovascular risk factors. It is sometimes argued that the increased mortality observed with weight loss must depend on confounding or poor study designs. This review was conducted to summarize results from studies on intentional weight loss and mortality among healthy individuals, while carefully considering the designs and problems in these studies. Evaluation criteria with a rating scale were developed. Of the studies evaluated, two found decreased mortality with intentional weight loss, three found increased mortality, and four found no significant associations between intentional weight loss and total mortality. Thus, it is still not possible for health authorities to make secure recommendations on intentional weight loss. More studies designed to specifically address this issue are warranted.
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ABSTRACT: To assess the validity of self-reported height and weight by comparison with measured height and weight in a sample of middle-aged men and women, and to determine the extent of misclassification of body mass index (BMI) arising from differences between self-reported and measured values. Analysis of self-reported and measured height and weight data from participants in the Oxford cohort of the European Prospective Investigation into Cancer and Nutrition (EPIC-Oxford). Four thousand eight hundred and eight British men and women aged 35-76 years. Spearman rank correlations between self-reported and measured height, weight and BMI were high (r > 0.9, P < 0.0001). Height was overestimated by a mean of 1.23 (95% confidence interval (CI) 1.11-1.34) cm in men and 0.60 (0.51-0.70) cm in women; the extent of overestimation was greater in older men and women, shorter men and heavier women. Weight was underestimated by a mean of 1.85 (1.72-1.99) kg in men and 1.40 (1.31-1.49) kg in women; the extent of underestimation was greater in heavier men and women, but did not vary with age or height. Using standard categories of BMI, 22.4% of men and 18.0% of women were classified incorrectly based on self-reported height and weight. After correcting the self-reported values using predictive equations derived from a 10% sample of subjects, misclassification decreased to 15.2% in men and 13.8% in women. Self-reported height and weight data are valid for identifying relationships in epidemiological studies. In analyses where anthropometric factors are the primary variables of interest, measurements in a representative sample of the study population can be used to improve the accuracy of estimates of height, weight and BMI.Public Health Nutrition 08/2002; 5(4):561-5. · 2.25 Impact Factor
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ABSTRACT: There are many good reasons to expect that weight loss in overweight and obese subjects should lead to reduced mortality, not least because the general risk factor profile of several diseases responsible for the excess mortality associated with overweight and obesity improves with weight loss. However, observational long-term population studies have shown that weight loss in overweight subjects leads to increased long-term mortality, even if the studies are well controlled with regard to known confounding factors, including hazardous behaviour and underlying diseases that may lead to both weight loss and increased mortality. It seems unfeasible to wait for the multiple randomized clinical trials of sufficient quality, size and duration that may resolve this question. Therefore, the recommendations about weight loss must be based on the weaker evidence that can be obtained in short-term clinical trials and the observational population studies. Several studies have tried to address the problem by distinguishing intentional from unintentional weight loss, but only few do so by gathering information about the intention to lose weight before weight loss is observed. These studies suggest that intentional weight loss is associated with increased mortality. Recommendations to healthy overweight and obese subjects to lose weight must be based on an explicit weighing of the short-term well-documented benefits of weight loss, including improvement of quality of life, against the possible risk of an increased mortality in the long-termObesity Reviews 03/2003; 4(1):3-7. · 6.87 Impact Factor
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ABSTRACT: Short-term studies indicate that intentional weight loss (IWL) among obese persons significantly improves health variables that are often precursors or markers of chronic diseases (e.g. heart diseases, type-2 diabetes). Hence, it is logical to assume that IWL among obese persons would lead to increased longevity. On the whole, epidemiological studies, including recent ones that use conservative analytic approaches such as distinguishing between apparently IWL and unintentional weight loss (UWL), adjusting for potential confounders and excluding apparently unhealthy subjects, indicate that apparently IWL appears to neither increase nor decrease mortality rate. However, it is important to note that none of the existing studies were designed specifically to test the hypothesis that IWL reduces mortality rate, and given methodological problems, these studies do not provide a satisfactory way to address the body mass index (BMI)-mortality question. Several controlled clinical trials suggest that IWL may reduce mortality rate. However, even in these studies, it is important to acknowledge that subjects are randomized to conditions that produce more or less weight loss and not to distinct levels of weight loss per se. Nevertheless, while we await additional data from better designed studies, given our incomplete knowledge, we conclude that it seems more likely than not that IWL achieved by medically recommended methods does not increase and probably decreases mortality rate.Obesity Reviews 03/2003; 4(1):9-16. · 6.87 Impact Factor