Metabolic syndrome
Global body mass index in men and women
Age-standardized global body mass index for women (part a)and men (part b). Data obtained from the WHO (2014). Reproduced with permission of the World Health Organization.
Evolution of obesity prevalence
Since 1975, the global obesity prevalence has almost tripled. The prevalence of obesity is higher in women than in men. Figure obtained from smoothed regression analysis based on data provided in REFS 1,21,24.
Critical periods in the development of obesity
The first thousand days, from conception until the end of the second year of life, mark the first critical period in the development of obesity. Body mass index (BMI) usually increases until 7 months of age, when it reaches a temporary maximum (the so‑called infant BMI peak). Between 5 and 7 years of age, the BMI reaches a minimum in children with adequate growth and development, after which it starts to rise again(that is, the adiposity rebound). During adolescence, BMI changes are substantially associated with puberty.Body weight at these critical periods is associated with later body composition.
Key factors involved in the regulation of energy balance
The energy balance is influenced by several biological factors. Although this balance indirectly relates to the first thermodynamic law, it cannot be translated to the level of causality.The pyramid holding the balance emphasizes the notion that we need to go beyond individual factors to ultimately have an optimal effect on the energy balance equation.*Could be affected by genetic and epigenetic factors.
Healthy dietary patterns
The relationship between the body mass index and mortality and
morbidity risk
The graph shows the increased health risk associated with extreme leanness and obesity. In addition, the upper and lower dashed lines illustrate the notion
that a positive relationship between body mass index (BMI) and health outcome can be modulated by several factors. Factors that increase the risk for a given BMI include increased age, smoking, sedentary behaviours, diet of poor nutritional quality, excess of abdominal visceral adipose tissue and ectopic fat, and poor cardiorespiratory fitness.Factors that decrease the health risk for a given BMI are, for example, physically active lifestyle, high level of cardiorespiratory fitness, high-quality diet, and low levels of visceral adipose tissue or ectopic fat.
Control of hunger and satiety
Pathological changes in adipose tissue
A large-scale study revealed that the absolute value of visceral fat area correlated with obesity-associated cardiovascular risks,but cardiovascular risks did not increase with the increase of subcutaneous fat.Accordingly, adipose tissues in subcutaneous fat obesity might function normally with the expected release of anti-inflammatory adipokines, whereas adipose tissues in visceral fat obesity release an increased amount of pro-inflammatory adipokines and
suppress the secretion of anti-inflammatory adipocytokines, thereby creating low-grade inflammation, which contributes to systemic metabolic and cardiovascular impairment that is associated with obesity-related disorders. Pathological changes in visceral adipose tissue show higher levels of adipocyte necrosis, owing in part to abnormal oxygen tension in the expanded fat depots, and the recruitment of macrophages with an inflammatory phenotype (M1 macrophages) that are arranged around dead cells in crown-like structures. PAI1, prothrombin activator inhibitor 1; RBP4, retinol-binding
protein 4; SFRP5, secreted frizzled-related protein 5; TNF, tumour necrosis factor.
Tools available to determine body composition
US FDA-approved drugs for the treatment of obesity
Bariatric surgery
a | The abdominal gastric band is an inflatable silicone band placed just below the gastro-oesophageal junction to create a small gastric pouch with a narrow stoma. A subcutaneous port, which allows adjustment of the tightness, is attached to the band. Frequent follow‑up is essential to achieve the optimal band tightness for each patient. This procedure is technically easy, but weight loss is less than with other bariatric procedures.
b | The sleeve gastrectomy involves placement of a staple line along the greater curvature of the stomach, followed by the removal of the closed stomach. This produces an elongation from the oesophago-gastric junction to the pylorus. This procedure is now among the most widely performed, and the weight loss is comparable to the Roux‑en‑Y gastric bypass.
c | The Roux‑en‑Y gastric bypass involves laparoscopic division of the jejunum approximately 50 cm from the ligament of Treitz, and the proximal end of the jejunum is anastomosed to the distal part of the jejunum about 150 cm below the site of transection,producing a jejunojejunostomy. The resultant 150 cm Roux limb of the proximal jejunum is brought up and anastomosed to the small proximal gastric pouch, providing a volume of about 15–30 ml. This procedure is more technically demanding,but competes with the sleeve gastrectomy. Reproduced with permission from REF, Macmillan Publishers Limited.
HRQOL tools use in QOL research in obesity
New treatment strategies under investigation
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