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Tessier D.R.,University of Ottawa | Tessier D.R.,Ottawa Hospital Research Institute | Ferraro Z.M.,Eastern Research Group | Gruslin A.,Ottawa Hospital Research Institute
Placenta | Year: 2013

Maternal obesity is associated with increased risks of pregnancy complications. Excessive fat mass, common to obese women, has the potential to influence production and secretion of adipose tissue derived proteins called adipokines. The adipokine leptin is involved in the regulation of multiple aspects of maternal metabolic homeostasis. In addition, leptin has been shown to be important for placentation and maternal-fetal exchanges processes regulating growth and development. In later stages of a healthy pregnancy, central leptin resistance occurs to allow increased nutrient availability for the fetus. Disruption of the signaling capacity of leptin associated with obesity is emerging as a potential risk factor leading to pregnancy complications as a result of aberrant fuel partitioning in utero. In this review we discuss the influence of obesity on the roles of leptin and leptin resistance at the central and placental level. © 2012 Elsevier Ltd. All rights reserved. Source


Chaput J.-P.,Eastern Research Group | Doucet E.,University of Ottawa | Tremblay A.,Laval University
Obesity Reviews | Year: 2012

Obesity is characterized by the accumulation of excess body fat and can be conceptualized as the physical manifestation of chronic energy excess. An important challenge of today's world is that our so-called obesogenic environment is conducive to the consumption of energy and unfavourable to the expenditure of energy. The modern, computer-dependent, sleep-deprived, physically inactive humans live chronically stressed in a society of food abundance. From a physiological standpoint, the excess weight gain observed in prone individuals is perceived as a normal consequence to a changed environment rather than a pathological process. In other words, weight gain is a sign of our contemporary way of living or a 'collateral damage' in the physiological struggle against modernity. Additionally, substantial body fat loss can complicate appetite control, decrease energy expenditure to a greater extent than predicted, increase the proneness to hypoglycaemia and its related risk towards depressive symptoms, increase the plasma and tissue levels of persistent organic pollutants that promote hormone disruption and metabolic complications, all of which are adaptations that can increase the risk of weight regain. In contrast, body fat gain generally provides the opposite adaptations, emphasizing that obesity may realistically be perceived as an a priori biological adaptation for most individuals. Accordingly, prevention and treatment strategies for obesity should ideally target the main drivers or root causes of body fat gain in order to be able to improve the health of the population. © 2012 The Authors. obesity reviews © 2012 International Association for the Study of Obesity. Source


Chaput J.-P.,Eastern Research Group
Physiology & behavior | Year: 2014

There is increasing evidence showing that sleep has an influence on eating behaviors. Short sleep duration, poor sleep quality, and later bedtimes are all associated with increased food intake, poor diet quality, and excess body weight. Insufficient sleep seems to facilitate the ingestion of calories when exposed to the modern obesogenic environment of readily accessible food. Lack of sleep has been shown to increase snacking, the number of meals consumed per day, and the preference for energy-rich foods. Proposed mechanisms by which insufficient sleep may increase caloric consumption include: (1) more time and opportunities for eating, (2) psychological distress, (3) greater sensitivity to food reward, (4) disinhibited eating, (5) more energy needed to sustain extended wakefulness, and (6) changes in appetite hormones. Globally, excess energy intake associated with not getting adequate sleep seems to be preferentially driven by hedonic rather than homeostatic factors. Moreover, the consumption of certain types of foods which impact the availability of tryptophan as well as the synthesis of serotonin and melatonin may aid in promoting sleep. In summary, multiple connections exist between sleep patterns, eating behavior and energy balance. Sleep should not be overlooked in obesity research and should be included as part of the lifestyle package that traditionally has focused on diet and physical activity. © 2013. Source


Tremblay A.,Laval University | Royer M.-M.,Laval University | Chaput J.-P.,Eastern Research Group | Doucet E.,University of Ottawa
International Journal of Obesity | Year: 2013

The decrease in energy expenditure that occurs during weight loss is a process that attenuates over time the impact of a restrictive diet on energy balance up to a point beyond which no further weight loss seems to be possible. For some health professionals, such a diminished energy expenditure is the normal consequence of a progressive decrease in the motivation to exercise over the course of a weight-reducing program. Another explanation of decreased energy needs during weight loss is the decrease in body energy stores (that is, fat mass and muscle mass) and its related obligatory costs of living. Many studies have also documented the existence of adaptive thermogenesis in the context of weight loss, which represents a greater-than-predicted decrease in energy expenditure. In this paper, we pursue the analysis of this phenomenon by demonstrating that an adaptive decrease in thermogenesis can have a major role in the occurrence of resistance to further lose fat in weight-reduced obese individuals. Evidence is also presented to support the idea of greater hunger sensations in individuals displaying more pronounced thermogenic changes. Finally, as the decrease in thermogenesis persists over time, it is also likely associated with a greater predisposition to body-weight regain after weight loss. Globally, these observations suggest that the adaptive reduction in thermogenesis that accompanies a prolonged negative energy balance is a major determinant of the ability to spontaneously lose body fat. © 2013 Macmillan Publishers Limited. Source


Chaput J.-P.,Eastern Research Group | Tremblay A.,Laval University
Obesity Facts | Year: 2012

Objective: To verify whether sleep quantity and quality at baseline predict the magnitude of fat loss in adults subjected to moderate caloric restriction. Methods: A total of 123 overweight and obese men and women (age, 41.1 ± 6.0 years; BMI, 33.2 ± 3.6 kg/m2 (mean ± SD)) underwent a weight loss intervention consisting of a targeted 600-700 kcal/day decrease in energy intake supervised by a dietician. The length of the intervention varied between 15 and 24 weeks. Body fat mass (dual-energy X-ray absorptiometry), sleep quality (total Pittsburgh Sleep Quality Index score) and sleep duration (h/night, self-reported from the Pittsburgh Sleep Quality Index) were assessed at both baseline and at the end of the weight loss program. Results: The mean weight loss over the dietary intervention was 4.5 ± 3.9 kg, 76% of which came from fat stores. Using a multiple linear regression analysis, we observed a significant positive relationship between sleep duration and the loss of body fat, both in absolute (adjusted β = 0.72 kg/h; p < 0.05) as well as in relative terms (adjusted β = 0.77%/h; p < 0.01), after adjusting for age, sex, baseline BMI, length of the intervention, and change in total energy intake. Furthermore, we observed that a better sleep quality at baseline was associated with greater fat mass loss. Conclusion: This study provides evidence that sleeping habits can influence the success of a weight loss intervention and should be taken into consideration when one decides to start a diet. Copyright © 2012 S. Karger GmbH, Freiburg. Source

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