Fitness, adiposopathy, and adiposity are independent predictors of insulin sensitivity in middle-aged men without diabetes

Adiposopathy, or sick fat, refers to adipose tissue dysfunction that can lead to several complications such as dyslipidemia, insulin resistance, and hyperglycemia. The relative contribution of adiposopathy in predicting insulin resistance remains unclear. We investigated the relationship between adiposopathy, as assessed as a low plasma adiponectin/leptin ratio, with anthropometry, body composition (hydrostatic weighing), insulin sensitivity (hyperinsulinemic-euglycemic clamp), inflammation, and fitness level (ergocycle VO2max, mL/kgFFM/min) in 53 men (aged 34-53 years) from four groups: sedentary controls without obesity (body mass index [BMI] <25 kg/m2), sedentary with obesity (BMI > 30 kg/m2), sedentary with obesity and glucose intolerance, and endurance trained active without obesity. The adiponectin/leptin ratio was the highest in trained men (4.75 ± 0.82) and the lowest in glucose intolerant subjects with obesity (0.27 ± 0.06; ANOVA p < 0.0001) indicating increased adiposopathy in those with obesity. The ratio was negatively associated with adiposity (e.g., waist circumference, r = −0.59, p < 0.01) and positively associated with VO2max (r = 0.67, p < 0.01) and insulin sensitivity (M/I, r = 0.73, p < 0.01). Multiple regression analysis revealed fitness as the strongest independent predictor of insulin sensitivity (partial R2 = 0.61). While adiposopathy was also an independent and significant contributor (partial R2 = 0.10), waist circumference added little power to the model (partial R2 = 0.024). All three variables remained significant independent predictors when trained subjects were excluded from the model. Plasma lipids were not retained in the model. We conclude that low fitness, adiposopathy, as well as adiposity (and in particular abdominal obesity) are independent contributors to insulin resistance in men without diabetes (AU)

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Fitness, adiposopathy, and adiposity are independent predictors of insulin sensitivity in middle-aged men without diabetes.

Adiposopathy, or sick fat, refers to adipose tissue dysfunction that can lead to several complications such as dyslipidemia, insulin resistance, and hyperglycemia. The relative contribution of adiposopathy in predicting insulin resistance remains unclear. We investigated the relationship between adiposopathy, as assessed as a low plasma adiponectin/leptin ratio, with anthropometry, body composition (hydrostatic weighing), insulin sensitivity (hyperinsulinemic-euglycemic clamp), inflammation, and fitness level (ergocycle VO2max, mL/kgFFM/min) in 53 men (aged 34-53 years) from four groups: sedentary controls without obesity (body mass index [BMI] <25 kg/m(2)), sedentary with obesity (BMI > 30 kg/m(2)), sedentary with obesity and glucose intolerance, and endurance trained active without obesity. The adiponectin/leptin ratio was the highest in trained men (4.75 ± 0.82) and the lowest in glucose intolerant subjects with obesity (0.27 ± 0.06; ANOVA p < 0.0001) indicating increased adiposopathy in those with obesity. The ratio was negatively associated with adiposity (e.g., waist circumference, r = -0.59, p < 0.01) and positively associated with VO2max (r = 0.67, p < 0.01) and insulin sensitivity (M/I, r = 0.73, p < 0.01). Multiple regression analysis revealed fitness as the strongest independent predictor of insulin sensitivity (partial R (2) = 0.61). While adiposopathy was also an independent and significant contributor (partial R (2) = 0.10), waist circumference added little power to the model (partial R (2) = 0.024). All three variables remained significant independent predictors when trained subjects were excluded from the model. Plasma lipids were not retained in the model. We conclude that low fitness, adiposopathy, as well as adiposity (and in particular abdominal obesity) are independent contributors to insulin resistance in men without diabetes.

Screen and nonscreen sedentary behavior and sleep in adolescents.

OBJECTIVE: This study examined the associations between screen (computer, videogame, TV) and nonscreen (talking on the phone, doing homework, reading) sedentary time, and sleep in adolescents. PARTICIPANTS: Data were drawn from AdoQuest, a prospective investigation of 1843 grade 5 students aged 10-12 years at inception in the greater Montreal (Canada) area. METHODS: Data for this cross-sectional analysis on screen and nonscreen sedentary time, sleep duration, and daytime sleepiness were collected in 2008-2009 from 1233 participants (67% of 1843) aged 14-16 years. RESULTS: Computer and videogame use >2 hours per day was associated with 17 and 11 fewer minutes of sleep per night, respectively. Computer use and talking on the phone were both associated with being a short sleeper (<8 hour per night) (odds ratio =2.2 [1.4-3.4] and 3.0 [1.5-6.2], respectively), whereas TV time was protective (odds ratio=0.5 [0.3-0.8]). Participants who reported >2 hours of computer use or talking on the phone per day had higher daytime sleepiness scores (11.9 and 13.9, respectively) than participants who reported d2 hours per day (9.7 and 10.3, respectively). CONCLUSIONS: Computer use and time spent talking on the phone are associated with short sleep and more daytime sleepiness in adolescents. Videogame time is also associated with less sleep. Clinicians, parents, and adolescents should be made aware that sedentary behavior and especially screen-related sedentary behavior may affect sleep duration negatively and is possibly associated with daytime sleepiness.

Functional food and satiety. Impact of a satiating context effect on appetite control of non-obese men.

The aim of this study was to verify if the addition of satiating nutrients and a satiating context effect could influence appetite sensations, spontaneous energy intake and food appreciation under conditions of standardized energy density of a meal. Eighteen non-obese men were submitted to a control, a satiating, and a context effect condition composed of a standardized breakfast and an ad libitum test lunch (macaroni entrée plus chocolate cake). The satiating macaroni contained more proteins, unsaturated fats, fibres and calcium than the control macaroni despite similar energy density, appearance and palatability. In the context effect condition, participants believed they were eating "a highly satiating macaroni", but were served the control macaroni. Appreciation of the macaronis, quantities of macaroni and cake consumed and 4-h satiating potential were measured for each condition. Quantities of macaroni and dessert consumed did not differ between conditions. Satiating potential was greater for the context effect meal compared to the control and/or the satiating meals up to 4h after its consumption. The context effect macaroni obtained higher appreciation rates than the control and the satiating macaronis. The context effect may positively influence the appreciation toward a meal and contribute to increase its satiety potential for many hours.

Predictors of cardiovascular fitness in sedentary men.

The relative contribution of anthropometric and skeletal muscle characteristics to cardiorespiratory fitness was studied in sedentary men. Cardiorespiratory fitness (maximal oxygen consumption) was assessed using an incremental bicycle ergometer protocol in 37 men aged 34-53 years. Vastus lateralis muscle biopsy samples were used to assess fiber type composition (I, IIA, IIX) and areas, capillary density, and activities of glycolytic and oxidative energy metabolic pathway enzymes. Correlations (all p < 0.05) were observed between maximal oxygen consumption (L.min-1) and body mass (r = 0.53), body mass index (r = 0.39), waist circumference (r = 0.34), fat free mass (FFM; r = 0.68), fat mass (r = 0.33), the enzyme activity of cytochrome c oxidase (COX; r = 0.39), muscle type IIA (r = 0.40) and IIX (r = 0.50) fiber area, and the number of capillaries per type IIA (r = 0.39) and IIX (r = 0.37) fiber. When adjusted for FFM in partial correlations, all correlations were lost, with the exception of COX (r = 0.48). Stepwise multiple regression revealed that maximal oxygen consumption was independently predicted by FFM, COX activity, mean capillary number per fiber, waist circumference, and, to a lesser extent, muscle capillary supply. In the absence of regular physical activity, cardiorespiratory fitness is strongly predicted by the potential for aerobic metabolism of skeletal muscle and negatively correlated with abdominal fat deposition.

Cardiorespiratory fitness and components of the metabolic syndrome in sedentary men.

OBJECTIVE: To investigate the relationships between fitness and components of the metabolic syndrome in sedentary men. SUBJECTS AND METHODS: 39 subjects (34-53 years) were evaluated for fitness (VO(2max)) and anthropometric, metabolic, and skeletal muscle phenotypes. VO(2max) was assessed on a bicycle ergometer whereas other variables were obtained from an oral glucose tolerance test (OGTT), hydrostatic weighing, and a muscle biopsy. RESULTS: Pearson and partial correlations adjusted for fat mass (FM), waist circumference (WC), muscle enzyme activities (citrate synthase (CS), cytochrome c oxidase (COX)), and capillary density were used to investigate the independent relationships be tween variables. Negative correlations between VO(2max) and WC as well as blood pressure and OGTT test were observed. When adjusted for FM, correlations remained between VO(2max) and WC (r = -0.46, p < 0.01) and systolic blood pressure (r = -0.35, p < 0.05). When adjusted for WC and CS activity, all correlations were lost except for high-sensitivity C-reactive protein (hs-CRP) (r = -0.34, p < 0.05) which remained when adjusted for CS activity. Adjustment for COX activity failed to remove correlations with hs-CRP (r = -0.36, p < 0.05), age (r = 0.34, p < 0.05), WC (r = -0.35, p < 0.05), and blood pressure. Negative correlations persisted when fitness was adjusted for the mean number of capillaries. CONCLUSION: The effects of fitness on components of the metabolic syndrome in sedentary men are explained by abdominal obesity and muscle phenotypes.

Mid-thigh subcutaneous adipose tissue and glucose tolerance in the Quebec family study.

OBJECTIVE: To clarify the relationship between the amount of mid-thigh subcutaneous adipose tissue (SCAT) and glucose tolerance in men and women. METHODS: Midthigh and abdominal computed tomography (CT) scans were obtained from 63 men and 110 women from the Quebec Family Study. Areas and attenuations of adipose tissue compartments and skeletal muscle measured from CT scans were related to glycemia and insulinemia values from an oral glucose tolerance test (OGTT). RESULTS: Adjusted for age and fat mass or age and percent fat, negative relationships (all p < 0.05) between the surface area of mid-thigh SCAT and OGTT data (glucose and insulin area under the curve, glycemia and insulin at 120 min) were seen in men (r range -0.22 to -0.37) and women (r range -0.20 to -0.30). Similar but weaker tendencies were observed when correcting for visceral adiposity. Correlations of OGTT variables with ratios of midthigh SCAT to abdominal visceral adipose tissue and to fat mass revealed significant negative relationships in both genders. Tertile analyses showed better glucose handling in subjects with a higher content of mid-thigh SCAT. CONCLUSION: These data suggest that the preferential deposition of adipose tissue as mid-thigh SCAT is a strategy to prevent glucose intolerance.