2. Prevalence of abdominal obesity

active and pro-inflammatory and presents a higher cardiometabolic risk association and calcification of the coronary arteries than the body mass index (BMI) and has more impact on health than subcutaneous fat, presenting a risk factor for increased incidence of metabolic

Abdominal obesity (AO) is directly associated with increased VAF, and it is also associated with endothelial dysfunction, inflammation, insulin resistance, diabetes mellitus, hypercholes-

There are several methods available to measure AO. Waist circumference (WC) provides an indicator of central adiposity that is the most practical and easiest method used in large-scale epidemiological studies [4]. It is a good predictor of cardiometabolic morbidity and mortality, and it has also a positive association with visceral abdominal fat. However, WC does not allow us to differentiate between visceral fat and subcutaneous fat; methods such as absorptiometry by dual energy X-ray (DEXA), impedance, or densitometry can be used to handle this differ-

WC measurement requires correct and standardized procedures, which depend mainly on training and adequate equipment. A standardized technique requires that the person being measured removes bulky or tight garments, as well as shoes with heels, empties their bladder then stands in the upright position, with arms loosely positioned to the side. The tape is passed around the body and positioned mid-way between the iliac crest and costal margin of the lower rib, ensuring that it

Recommended waist circumference threshold

≥80 cm [increased risk]≥88 cm

[still higher risk]

Men Women

≥102 cm ≥88 cm

risk]≥102 cm [still higher risk]

IDF ≥90 cm ≥80 cm

Table 1. Waist circumference cutoffs recommended for the diagnosis of abdominal obesity according to ethnicity and

for abdominal obesity

terolemia, metabolic syndrome [MetS], and cancer [1, 3].

Organization (References)

Caucasian WHO ≥94 cm [increased

European European cardiovascular

societies

Europid IDF ≥94 cm ≥80 cm

United States AHA/NHLBI [ATP III] ≥102 cm ≥88 cm Canada Health Canada ≥102 cm ≥88 cm

Asian [including Japanese] IDF ≥90 cm ≥80 cm Asian WHO ≥90 cm ≥80 cm Japanese Japanese obesity society ≥85 cm ≥90 cm China Cooperative task force ≥85 cm ≥80 cm Middle East, Mediterranean IDF ≥94 cm ≥80 cm Sub-Saharan African IDF ≥94 cm ≥80 cm

syndrome [1, 2].

72 Adiposity - Epidemiology and Treatment Modalities

entiation [5–7].

Population

Ethnic Central and South

American

gender [9].

Populations worldwide have faced a growing "epidemics" of AO. Overweight and obesity across low- and middle-income countries (LMIC) have reached levels found in higher-income countries (HIC). Despite its high prevalence, there are differences among regions and countries, and these need to be taken into account for us to understand the etiology of AO.

To better elucidate this picture, Table 2 depicts the prevalence of AO according to gender in selected high and LMIC. LMIC showed the highest prevalence of AO, compared with HIC; in several studies, an increasing trend of AO in the past 10 years [10, 16, 17] has been observed. For example, in the study called China Health and Nutrition Survey (1993–2009), with 52,621 Chinese adults, the prevalence of AO increased from 8.5 to 27.8% among men and from 27.8 to 45.9% among women [17]. Similarly, in the USA, data from the National Health and Nutrition Examination Survey [NHANES] from 1999 to 2010 identified an increase over time, and the difference between genders was 20% higher for females [10].

Regarding gender, both in LMIC and in HIC, it was observed that women had a higher prevalence of AO than men. Also, recent studies show a higher prevalence of AO in women than men, in all ages. There is a proportional increase in the accumulation of fat in the abdominal region as people get older, but a stabilization or even a small decrease in the prevalence of AO in men after 60 years of age could be perceived [12, 18, 20]. In Brazil, in a study involving data from 3117 subjects, the prevalence of AO was found to be 26 and 73%, respectively, in women aged 24–34 years and 55–65 years. In men, the prevalence of AO was found to be 16.9% (24–34 years) and 27.2% (55–65 years) [20].

But why do women have a higher prevalence of AO than men? On one hand, sex hormones strongly influence body fat distribution and adipocyte differentiation between females and males, showing a physiological difference in the AO determination between sexes. However, in part AO is due to a social construction, since socioeconomic, cultural, and behavioral characteristics play an important role in its causal chain.


Cutoffs of WC for AO = <sup>1</sup> ≥102 cm (males) and ≥88 cm (females); <sup>2</sup> >102 cm (males) and >88 cm (females); <sup>3</sup> >90 cm (males) and >80 cm (females); <sup>4</sup> ≥90 cm (males) and ≥80 cm (females).

Table 2. Prevalence of AO according to gender in selected high- and low-middle-income countries.

To better understand this topic, it is important to elucidate the differences between sex (biology) and gender (the social). According to Annandale and Hunt [21], this distinction was essential to make it clear that gender inequalities in health were, in the most part, socially produced, rather than biologically given. Olinto [22] also called attention to the operationalization of the gender category in epidemiological studies. Sex only means the genetic, anatomical, and physiological characterization of human beings. However, gender roles are socially constructed and usually framed as an extension of biologically determined social functions. The pioneering feminist Simone de Beauvoir said in her famous quote: "One is not born, but rather becomes, a woman." Though the positions of women and men are not simply parallel, the principle is also true for men: One is not born masculine, but has to become a man [23]. Thus, gender is related to differences in patterns of employment, education, family, and household structure, leisure and consumption at the societal level, and in the everyday experience of individual men and women [21]. In this sense, we describe the possible biological and social factors associated with AO according to gender differences.
