D. Prud’homme

Overweight and obese teenagers: why is adolescence a critical period?

This paper discusses the critical period of adolescence and its potential role in the development and persistence of obesity. The adolescent years are characteristic of changes in body composition (location and quantity of body fat), physical fitness and decreased insulin sensitivity during puberty. This period of growth and maturation is also marked with behavioural changes in diet, physical activity, sedentary behaviour and psychological health. Physical activity and sport participation decline during adolescence especially in teenage girls, while sedentary behaviour, risk for depression and body esteem issues increase during the teenage years. These physiological and behavioural changes during adolescence warrant the attention of health practitioners to prevent the onset and continuation of obesity throughout the lifespan.

Excessive gestational weight gain predicts large for gestational age neonates independent of maternal body mass index

Objective: To determine the effects of maternal pre-pregnancy body mass index (BMI) and gestational weight gain (GWG) on large-for-gestational-age (LGA) birth weight (≥90th % ile). Methods: We examined 4321 mother-infant pairs from the Ottawa and Kingston (OaK) birth cohort. Multivariate logistic regression (controlling for gestational and maternal age, pre-pregnancy weight, parity, smoking) were performed and odds ratios (ORs) calculated. Results: Prior to pregnancy, a total of 23.7% of women were overweight and 16.2% obese. Only 29.3% of women met GWG targets recommended by the Institute of Medicine (IOM), whereas 57.7% exceeded the guidelines. Adjusting for smoking, parity, age, maternal height, and achieving the IOM’s recommended GWG, overweight (OR 1.99; 95%CI 1.17–3.37) or obese (OR 2.64; 95% CI 1.59–4.39) pre-pregnancy was associated with a higher rate of LGA compared to women with normal BMI. In the same model, exceeding GWG guidelines was associated with higher rates of LGA (OR 2.86; 95% CI 2.09–3.92), as was parity (OR 1.49; 95% CI 1.22–1.82). Smoking (OR 0.53; 95%CI 0.35–0.79) was associated with decreased rates of LGA. The adjusted association with LGA was also estimated for women who exceeded the GWG guidelines and were overweight (OR 3.59; 95% CI 2.60–4.95) or obese (OR 6.71; 95% CI 4.83–9.31). Conclusion: Pregravid overweight or obesity and gaining in excess of the IOM 2009 GWG guidelines strongly increase a woman’s chance of having a larger baby. Lifestyle interventions that aim to optimize GWG by incorporating healthy eating and exercise strategies during pregnancy should be investigated to determine their effects on LGA neonates and down-stream child obesity.

Apolipoprotein B: a predictor of inflammatory status in postmenopausal overweight and obese women

Aims/hypothesisInflammation is implicated in the development of type 2 diabetes and CHD, but the trigger of inflammation is unclear. Although in vitro and animal studies support a role of elevated levels of atherosclerotic lipoproteins in the activation of inflammation, plasma cholesterol cannot predict inflammatory markers in humans. Moreover, the association between inflammatory markers and other traditional risk factors of diabetes and CHD is unclear. To increase our knowledge of in vivo regulation of inflammation, we examined the association between several traditional risk factors and inflammatory markers. We hypothesised that because apolipoprotein B (ApoB) reflects atherogenic particle number, it is the primary predictor of inflammatory status.Subjects, materials and methodsWe examined the association between several traditional risk factors and plasma high-sensitivity (hs) C-reactive protein (CRP), hsTNF-α, soluble TNF receptor 1, IL-6, orosomucoid, haptoglobin and α1-antitrypsin in 77 non-diabetic overweight and obese postmenopausal women.ResultsThe inflammatory markers correlated positively with total and abdominal adiposity, blood pressure, 2-h OGTT glucose, insulin resistance, triglyceride, total/HDL cholesterol, ApoB, ApoB:apolipoprotein A1 (ApoA1) ratio and Framingham CHD risk points. They correlated negatively with ApoA1, and total, LDL and HDL cholesterol. ApoB was an independent predictor of the interindividual variation in IL-6, hsCRP, orosomucoid, haptoglobin and α1-antitrypsin (R2 range 8–40%); other risk factors were less predictive. Compared with BMI-matched control subjects, women with hyperapobetalipoproteinaemia (hyperapoB) had higher hsTNF-α, IL-6, hsCRP and orosomucoid (increase 17–104%).Conclusions/interpretationApoB is the primary predictor of inflammatory markers in postmenopausal overweight and obese women. Given elevated levels of inflammatory markers in hyperapoB women, we hypothesise that hyperapoB women may have an increased risk of developing both CHD and diabetes.

Leisure Physical Activity is Associated with Quantitative Ultrasound Measurements Independently of Bone Mineral Density in Postmenopausal Women

The purpose of this study was to assess the magnitude of the relationship between leisure physical activity and bone status as measured either by an AchillesTM ultrasound bone densitometer (QUS) or dual-energy X-ray absorptiometry (DXA) in postmenopausal women. We studied 1162 French Canadian postmenopausal women, aged 33–84 years (mean age 58 years), for QUS parameters [broadband ultrasound attenuation (BUA), speed of sound (SOS), and stiffness index (SI)] measured at the right calcaneus, and bone mineral density (BMD) measured at the lumbar spine and femoral neck. Multivariate regression analyses revealed that leisure physical activity level was an independent predictor of the heel QUS parameters and of femoral neck BMD. No such association was observed for BMD of the lumbar spine. Heel QUS parameters (BUA, SOS, SI) and femoral neck BMD adjusted for interfering covariables showed a statistically significant difference between sedentary (less than three sessions/month) and active women (three or more sessions/week) (P ≤ 0.001). Furthermore, after adjusting each heel QUS parameters for the mean lumbar spine BMD value, the association observed between leisure physical activity and QUS remained significant. These results suggest that regular leisure physical activity could influence QUS parameters, independently of BMD, and that quantitative ultrasound could be a suitable outcome measure in exercise studies in postmenopausal women.

Ovariectomy Stimulates Hepatic Fat and Cholesterol Accumulation in High-fat Diet-fed Rats

This study was designed to determine how estrogens withdrawal during a high-fat (HF) diet regimen affects liver triacylglycerol (TAG) and cholesterol accumulation. Female Sprague-Dawley rats were submitted to a HF (42% energy as fat) or a standard (SD) diet for 6 weeks before being either ovariectomized (Ovx) or sham operated (Sham). Thereafter, Ovx and Sham rats were kept on the same diet for another 6 weeks leading to euthanasia. Liver TAG content was increased (p<0.01) in Ovx rats but not by the HF diet alone. However, the combination of HF diet and Ovx resulted in a greater liver TAG accumulation (p<0.06) than that observed in Ovx-SD/SD. Measurement of molecular markers of liver lipid metabolism revealed an increase in transcripts of markers of lipid oxidation (CPT-1 and PGC1; p<0.05) in rats fed the HF diet. This increase was, however, substantially less if HF fed rats were Ovx. Liver total cholesterol levels were increased (p<0.01) only in the Ovx-HF/HF rats while plasma cholesterol levels were increased in Ovx-SD/SD and in SHAM-HF/HF and Ovx-HF/HF rats. Transcripts of molecular markers of cholesterol metabolism suggest that biliary acids synthesis (CYP7a-1) was reduced in Ovx-SD/SD and Sham-HF/HF rats and even more so in Ovx-HF/HF rats. It is concluded that the effects of a HF diet on liver TAG accumulation are especially observed in Ovx rats possibly through a reduction in hepatic lipid oxidation. The combination of Ovx and HF diet also acts synergistically to favor liver cholesterol accumulation.

Evaluation of two new surrogate indices including parameters not using insulin to assess insulin sensitivity/resistance in non-diabetic postmenopausal women: A MONET group study

AIM The study evaluated and compared, with other surrogate indices of insulin sensitivity/resistance (IS/R), the relevance of the TyG index, a product of fasting glucose and triglyceride (TG) levels, and the EGIR index, which includes TG, high-density lipoprotein cholesterol (HDL-c) and waist circumference in its formula to estimate IS/R, in non-diabetic postmenopausal women. METHODS A secondary analysis was performed using the baseline data for 163 non-diabetic postmenopausal women from the Montreal-Ottawa New Emerging Team (MONET) population database. The subjects participated in hyperinsulinaemic-euglycaemic (HIEG) clamp and oral glucose tolerance (OGTT) tests. Correlations and comparisons between surrogate indices were performed in addition to inter-rater agreement tests. The optimal value of surrogate indices for diagnosis of IS/R was established on a receiver operating characteristic (ROC) scatter plot. RESULTS A significant correlation was found between the HIEG clamp and all IS/R surrogate indices tested [r=-0.370 (TyG index) to 0.608 (SIisOGTT index); P<0.001]. On ROC curve analysis, a higher AUROC was found for SIisOGTT (0.791) than for TyG and EGIR (0.706 and 0.675, respectively; P=0.07 and P<0.05, respectively). CONCLUSION The TyG and EGIR IS/R indices were only relatively modestly related to the HIEG clamp. In contrast, both fasting- and OGTT-derived IS/R surrogate indices, which include insulin values in their formulae, appeared to be more accurate in estimating IS/R in our study population. Thus, the TyG and EGIR IS/R indices need to be tested and validated more extensively in different populations before being put to large-scale clinical use.

Vasomotor symptoms and cardiometabolic risk factors in menopausal women: a MONET Group study

Abstract Introduction: Conflicting results have been reported concerning the prevalence of cardiometabolic risk factors in women experiencing vasomotor symptoms (VMS). Objectives: To compare cardiometabolic risk factors between women with and without VMS during the menopause transition and to determine the influence of physical activity on the prevalence of VMS. Methods: Yearly assessment of women transitioning through menopause included self-reported VMS (hot flushes and night sweats), body composition and fat distribution, fasting glucose, insulin and lipids, and physical activity levels. Results: Eighty-five of the 102 premenopausal women at baseline were included (age: 49.9 ± 2.0 years; body mass index: 23.2 ± 2.2 kg/m2). According to linear mixed model analyses, no statistically significant differences were observed for fat mass, lean body mass, body fat distribution indices and cardiometabolic risk factors, when comparing symptomatic vs. asymptomatic women. Neither physical activity levels nor intensity were associated with the prevalence of VMS. Conclusion: Our results suggest that women transitioning through menopause who reported VMS did not show greater deteriorations in body composition, body fat distribution and cardiometabolic risk factors. Furthermore, physical activity levels were not associated with lower prevalence of vasomotor symptoms in the present cohort.