Predicting risk of substantial weight gain in German adults-a multi-center cohort approach.

Background: A risk-targeted prevention strategy may efficiently utilize limited resources available for prevention of overweight and obesity. Likewise, more efficient intervention trials could be designed if selection of subjects was based on risk. The aim of the study was to develop a risk score predicting substantial weight gain among German adults. Methods: We developed the risk score using information on 15 socio-demographic, dietary and lifestyle factors from 32 204 participants of five population-based German cohort studies. Substantial weight gain was defined as gaining ≥10% of weight between baseline and follow-up (>6 years apart). The cases were censored according to the theoretical point in time when the threshold of 10% baseline-based weight gain was crossed assuming linearity of weight gain. Beta coefficients derived from proportional hazards regression were used as weights to compute the risk score as a linear combination of the predictors. Cross-validation was used to evaluate the score's discriminatory accuracy. Results: The cross-validated c index (95% CI) was 0.71 (0.67-0.75). A cutoff value of ≥475 score points yielded a sensitivity of 71% and a specificity of 63%. The corresponding positive and negative predictive values were 10.4% and 97.6%, respectively. Conclusions: The proposed risk score may support healthcare providers in decision making and referral and facilitate an efficient selection of subjects into intervention trials.

Main nutrient patterns are associated with prospective weight change in adults from 10 European countries.

PURPOSE: Various food patterns have been associated with weight change in adults, but it is unknown which combinations of nutrients may account for such observations. We investigated associations between main nutrient patterns and prospective weight change in adults. METHODS: This study includes 235,880 participants, 25-70 years old, recruited between 1992 and 2000 in 10 European countries. Intakes of 23 nutrients were estimated from country-specific validated dietary questionnaires using the harmonized EPIC Nutrient DataBase. Four nutrient patterns, explaining 67 % of the total variance of nutrient intakes, were previously identified from principal component analysis. Body weight was measured at recruitment and self-reported 5 years later. The relationship between nutrient patterns and annual weight change was examined separately for men and women using linear mixed models with random effect according to center controlling for confounders. RESULTS: Mean weight gain was 460 g/year (SD 950) and 420 g/year (SD 940) for men and women, respectively. The annual differences in weight gain per one SD increase in the pattern scores were as follows: principal component (PC) 1, characterized by nutrients from plant food sources, was inversely associated with weight gain in men (-22 g/year; 95 % CI -33 to -10) and women (-18 g/year; 95 % CI -26 to -11). In contrast, PC4, characterized by protein, vitamin B2, phosphorus, and calcium, was associated with a weight gain of +41 g/year (95 % CI +2 to +80) and +88 g/year (95 % CI +36 to +140) in men and women, respectively. Associations with PC2, a pattern driven by many micro-nutrients, and with PC3, a pattern driven by vitamin D, were less consistent and/or non-significant. CONCLUSIONS: We identified two main nutrient patterns that are associated with moderate but significant long-term differences in weight gain in adults.

Weight cycling and the risk of type 2 diabetes in the EPIC-Germany cohort.

AIMS/HYPOTHESIS: Studies on weight cycling and the risk of type 2 diabetes have revealed inconsistent results, possibly due to differences in the definition of weight fluctuations. Here, we investigated whether weight cycling during adulthood is related to diabetes risk in a large cohort study, using a complementary approach to define patterns of weight development. METHODS: Weight cycling, weight loss and weight gain were defined (1) a priori, using distinct categories, and (2) by functional principal component analysis (FPCA) to capture weight patterns in greater detail. Associations of weight cycling, weight loss and weight gain with the risk of type 2 diabetes were evaluated by Cox regression models. RESULTS: A priori defined weight cycling was associated with increased diabetes risk, compared with stable weight (HR 1.36 [95% CI 1.09, 1.68]). No significant association between FPCA-derived weight cycling and risk of diabetes was observed after adjustment for concurrent weight patterns (HR 1.19 [95% CI 0.89, 1.60]). Subgroup analyses showed that FPCA-derived weight cycling during net weight gain was associated with a higher risk of diabetes (HR 1.68 [95% CI 1.14, 2.48]). A priori defined weight gain (HR 2.08 [95% CI 1.60, 2.70]) was more clearly related to the risk of diabetes than FPCA-derived weight gain (HR 1.20 [95% CI 0.95, 1.51]), while no significant associations were observed for weight loss. CONCLUSIONS/INTERPRETATION: Overall, weight cycling may not be an independent risk factor for type 2 diabetes when accounting for concurrent patterns of weight development. However, weight cycling may pose a stronger risk of diabetes than non-cycling during net weight gain.

General and abdominal obesity and risk of esophageal and gastric adenocarcinoma in the European Prospective Investigation into Cancer and Nutrition.

General obesity, as reflected by BMI, is an established risk factor for esophageal adenocarcinoma (EAC), a suspected risk factor for gastric cardia adenocarcinoma (GCC) and appears unrelated to gastric non-cardia adenocarcinoma (GNCC). How abdominal obesity, as commonly measured by waist circumference (WC), relates to these cancers remains largely unexplored. Using measured anthropometric data from 391,456 individuals from the European Prospective Investigation into Cancer and Nutrition (EPIC) study and 11 years of follow-up, we comprehensively assessed the association of anthropometric measures with risk of EAC, GCC and GNCC using multivariable proportional hazards regression. One hundred twenty-four incident EAC, 193 GCC and 224 GNCC were accrued. After mutual adjustment, BMI was unrelated to EAC, while WC showed a strong positive association (highest vs. lowest quintile HR = 1.19; 95% CI, 0.63-2.22 and HR = 3.76; 1.72-8.22, respectively). Hip circumference (HC) was inversely related to EAC after controlling for WC, while WC remained positively associated (HR = 0.35; 0.18-0.68, and HR=4.10; 1.94-8.63, respectively). BMI was not associated with GCC or GNCC. WC was related to higher risks of GCC after adjustment for BMI and more strongly after adjustment for HC (highest vs. lowest quintile HR = 1.91; 1.09-3.37, and HR = 2.23; 1.28-3.90, respectively). Our study demonstrates that abdominal, rather than general, obesity is an indisputable risk factor for EAC and also provides evidence for a protective effect of gluteofemoral (subcutaneous) adipose tissue in EAC. Our study further shows that general obesity is not a risk factor for GCC and GNCC, while the role of abdominal obesity in GCC needs further investigation.

Can the use of blood-based biomarkers in addition to anthropometric indices substantially improve the prediction of visceral fat volume as measured by magnetic resonance imaging?

PURPOSE: To investigate whether blood-based biomarkers can improve the prediction of visceral fat volume as measured by magnetic resonance imaging (MRI) and thus be used as proxies of visceral adiposity in large-scale epidemiological studies. METHODS: Whole-body MRI was performed to determine overall and regional body compartments in 542 participants aged 48-80 years (52% men) of the Heidelberg cohort of the European Prospective Investigation into Cancer and Nutrition. Anthropometric measures were taken, and clinical chemistry profiles including 15 routine biomarkers were obtained. Furthermore, nine novel biomarkers of visceral fat were assayed in a discovery sample of 100 participants. Multivariable regression models were calculated to assess associations between anthropometric variables, biomarkers, and visceral fat volume. RESULTS: The proportion of variance in visceral fat volume explained by anthropometric measures was 65.2% in women and 60.8% in men. By using blood-based biomarkers in addition to anthropometric indices, the variance in visceral fat volume explained could be increased by 4.8% in women and 4.0% in men. After backward selection, HbA1c, triglycerides, and adiponectin remained in the final multivariable regression model in women, while in men hsCRP, leukocytes, AST (GOT), GGT, LDL, and adiponectin remained in the final model. CONCLUSIONS: In the present study, blood-based biomarkers moderately improved the prediction of visceral fat volume. This finding suggests that the underestimation of true associations between visceral fat and disease outcomes in epidemiological studies remains critical, even when using comprehensive sets of anthropometric and biomarker variables as proxies of visceral adiposity.

Socioeconomic status and anthropometric changes-A meta-analytic approach from seven German cohorts.

OBJECTIVE: To study the association between socioeconomic status (SES) and annual relative change in anthropometric markers in the general German adult population. METHODS: Longitudinal data of 56,556 participants aged 18-83 years from seven population-based German cohort studies (CARLA, SHIP, KORA, DEGS, EPIC-Heidelberg, EPIC-Potsdam, PopGen) were analyzed by meta-analysis using a random-effects model. The indicators of SES were education and household income. RESULTS: On average, all participants gained weight and increased their waist circumference over the study's follow-up period. Men and women in the low education group had a 0.1 percentage points greater annual increase in weight (95% CI men: 0.06-0.20; and women: 0.06-0.12) and waist circumference (95% CI men: 0.01-0.45; and women: 0.05-0.22) than participants in the high education group. Women with low income had a 0.1 percentage points higher annual increase in weight (95% CI 0.00-0.15) and waist circumference (95% CI 0.00-0.14) than women with high income. No association was found for men between income and obesity markers. CONCLUSIONS: Participants with lower SES (education and for women also income) gained more weight and waist circumference than those with higher SES. These results underline the necessity to evaluate the risk of weight gain based on SES to develop more effective preventive measures.

Changes in Waist Circumference among German Adults over Time - Compiling Results of Seven Prospective Cohort Studies.

AIM: This study aims to quantify longitudinal changes in waist circumference (WC) among adults aged 45-64 years in Germany. METHODS: Data of 15,444 men and 17,207 women from one nationwide and six regional prospective German cohort studies were analyzed. The sex-specific mean change in WC per year of follow-up was assessed for each study separately. Findings from the cohort-by-cohort analysis were combined by applying meta-analytic methods. Progression to central obesity (WC ≥ 102 cm in men and ≥ 88 cm in women) within a standardized period of 10 years was described for each study. RESULTS: The estimated mean change in WC per year of follow-up for all cohorts combined was 0.53 (95% confidence interval 0.29-0.76) cm/year for men and 0.63 (0.48-0.77) cm/year for women, but varied between the included studies. Within 10 years, about 20% of individuals with low WC (<94 cm in men; <80 cm in women) and about 50% of individuals with intermediate WC (94-102 cm in men; 80-88 cm in women) progressed to central obesity. CONCLUSION: The increase in mean WC with aging along with a profound increase of central adiposity is obviously and may have several adverse health effects. Obesity prevention programs should also focus on abdominal obesity.

Plasma elaidic acid level as biomarker of industrial trans fatty acids and risk of weight change: report from the EPIC study.

BACKGROUND: Few epidemiological studies have examined the association between dietary trans fatty acids and weight gain, and the evidence remains inconsistent. The main objective of the study was to investigate the prospective association between biomarker of industrial trans fatty acids and change in weight within the large study European Prospective Investigation into Cancer and Nutrition (EPIC) cohort. METHODS: Baseline plasma fatty acid concentrations were determined in a representative EPIC sample from the 23 participating EPIC centers. A total of 1,945 individuals were followed for a median of 4.9 years to monitor weight change. The association between elaidic acid level and percent change of weight was investigated using a multinomial logistic regression model, adjusted by length of follow-up, age, energy, alcohol, smoking status, physical activity, and region. RESULTS: In women, doubling elaidic acid was associated with a decreased risk of weight loss (odds ratio (OR) = 0.69, 95% confidence interval (CI) = 0.55-0.88, p = 0.002) and a trend was observed with an increased risk of weight gain during the 5-year follow-up (OR = 1.23, 95% CI = 0.97-1.56, p = 0.082) (p-trend<.0001). In men, a trend was observed for doubling elaidic acid level and risk of weight loss (OR = 0.82, 95% CI = 0.66-1.01, p = 0.062) while no significant association was found with risk of weight gain during the 5-year follow-up (OR = 1.08, 95% CI = 0.88-1.33, p = 0.454). No association was found for saturated and cis-monounsaturated fatty acids. CONCLUSIONS: These data suggest that a high intake of industrial trans fatty acids may decrease the risk of weight loss, particularly in women. Prevention of obesity should consider limiting the consumption of highly processed foods, the main source of industrially-produced trans fatty acids.

Validation of anthropometric indices of adiposity against whole-body magnetic resonance imaging--a study within the German European Prospective Investigation into Cancer and Nutrition (EPIC) cohorts.

BACKGROUND: In epidemiological studies, measures of body fat generally are obtained through anthropometric indices such as the body mass index (BMI), waist (WC), and hip circumferences (HC). Such indices, however, can only provide estimates of a person's true body fat content, overall or by adipose compartment, and may have limited accuracy, especially for the visceral adipose compartment (VAT). OBJECTIVE: To determine the extent to which different body adipose tissue compartments are adequately predicted by anthropometry, and to identify anthropometric measures alone, or in combination to predict overall adiposity and specific adipose tissue compartments, independently of age and body size (height). METHODS: In a sub-study of 1,192 participants of the German EPIC (European Prospective Investigation into Cancer and Nutrition) cohorts, whole-body MRI was performed to determine adipose and muscle tissue compartments. Additional anthropometric measurements of BMI, WC and HC were taken. RESULTS: After adjusting for age and height, BMI, WC and HC were better predictors of total body volume (TBV), total adipose tissue (TAT) and subcutaneous adipose tissue (SAT) than for VAT, coronary adipose tissue (CAT) and skeletal muscle tissue (SMT). In both sexes, BMI was the best predictor for TBV (men: r = 0.72 [0.68-0.76], women: r = 0.80 [0.77-0.83]) and SMT (men: r = 0.52 [0.45-0.57], women: r = 0.48 [0.41-0.54]). WC was the best predictor variable for TAT (r = 0.48 [0.41-0.54]), VAT (r = 0.44 [0.37-0.50]) and CAT (r = 0.34 [0.26-0.41]) (men), and for VAT (r = 0.42 [0.35-0.49]) and CAT (r = 0.29 [0.22-0.37]) (women). BMI was the best predictor for TAT (r = 0.49 [0.43-0.55]) (women). HC was the best predictor for SAT (men (r = 0.39 [0.32-0.45]) and women (r = 0.52 [0.46-0.58])). CONCLUSIONS: Especially the volumes of internal body fat compartments are poorly predicted by anthropometry. A possible implication may be that associations of chronic disease risks with the sizes of internal body fat as measured by BMI, WC and HC may be strongly underestimated.