Body image, body dissatisfaction and weight status of Pacific adolescents from different ethnic communities: a cross-sectional study in New Caledonia.

Objective(s): The prevalence of adolescent obesity is high among the various ethnic groups native to the Pacific region (European, Melanesian and Polynesian). An important factor of weight gain or loss is body size satisfaction; however, little is known about adolescent body self-perception in the Pacific region.Design: Body dissatisfaction was evaluated using the Stunkard Figure Rating Scale in a sample of 699 adolescents from rural and urban areas of New Caledonia. The socio-demographic factors associated with higher body dissatisfaction were determined by multiple linear regression modeling.Results: Our results showed a high rate of body dissatisfaction (over 70%) in the adolescents. Body dissatisfaction was strongly related to the body mass index z-score. Melanesians boys had higher body dissatisfaction scores when they felt 'too thin' while Melanesian girls showed lower body dissatisfaction when they felt 'too fat.'.Conclusion: These results showed that social pressure for thinness or musculature may be different among adolescents living in New Caledonia. These results should be taken into account in education overweight prevention programs.

Too big or too thin? New Caledonian adolescents' perceptions of overweight and underweight.

OBJECTIVES: The first aim was to examine New Caledonian adolescents' views of what constitutes an overweight or underweight person. The second aim was to assess whether an environment with a high prevalence of overweight is associated with different norms of overweight or underweight in this population. METHODS: The Stunkard Figure Rating Scale was used for a sample of 699 pluriethnic adolescents in New Caledonia. Body mass index (BMI) was assessed for each participant and weight status was determined. The factors associated with higher figure ratings were determined by linear regression modeling. RESULTS: Multilinear regression analysis indicated that gender (being male) and BMI were associated with higher rating scores to designate overweight. Moreover, higher BMI z-scores were associated with higher underweight figure ratings. Ethnicity, area of residence, age, and socioeconomic status were not associated with higher ratings of body image. CONCLUSIONS: These findings show that an environment with a high prevalence of overweight does not necessarily shift adolescent "norms," contrary to visual normalization theory. These results should be taken into account in educational overweight prevention programs.

Energy drink consumption in a pluri-ethnic population of adolescents in the Pacific.

OBJECTIVE: Energy drinks are very popular among teenagers but may cause health problems. Energy drink consumption is partly associated with energy drink perception, but little is known about this in the Pacific Island Countries and Territories. The aim of this cross-sectional study was to identify the relationships between energy drink consumption, energy drink perception, weight status and sociodemographic characteristics in a school-going sample of Pacific adolescents. DESIGN: A cross-sectional study carried out in the schools during school hours between July 2015 and April 2016. SETTING: Sociodemographic characteristics, weight status, energy drink perception, and quantity of energy drinks consumed were obtained. Chi-square tests of independence, independent t tests, multivariate logistic regressions and multiple linear regressions were used. SUBJECTS: A representative sample of 678 New Caledonian adolescents (11-16 years). RESULTS: We found that one third of New Caledonian adolescents consume energy drinks. Boys are more likely to drink them than girls and Polynesians drink significantly more than European and Melanesian adolescents. Higher energy drink consumption in the New Caledonian adolescents is associated with good or neutral perceptions of the energy drink impact on health. Moreover, sex (being male) significantly influences the total energy drink consumption per week. Energy drink consumers have a tendency toward better perceptions of energy drinks than non-consumers. CONCLUSIONS: Nutritional education targeting energy drink consumers should take these results into account by providing (community-based) educational programs, especially for adolescents from low socioeconomic backgrounds, boys, or those living in rural areas.

Sugar-Sweetened Beverage Consumption and Associated Factors in School-Going Adolescents of New Caledonia.

This cross-sectional study assessed sugar-sweetened beverage (SSB) consumption and its associations with the sociodemographic and physical characteristics, behavior and knowledge of New Caledonian adolescents. The survey data of 447 adolescents from ages 11 to 16 years were collected in five secondary public schools of New Caledonia between July 2015 and April 2016. These data included measured height and weight, SSB consumption, sociodemographic characteristics, body weight perception, physical activity, and knowledge (sugar quantity/SSB unit; energy expenditure required to eliminate a unit) and opinions about the SSB‒weight gain relationship. Ninety percent of these adolescents declared regularly drinking SSBs. Quantities were associated with living environment (1.94 L·week-1 in urban environment vs. 4.49 L·week-1 in rural environment, p = 0.001), ethnic community (4.77 L·week-1 in Melanesians vs. 2.46 L·week-1 in Caucasians, p < 0.001) and knowledge about energy expenditure (6.22 L·week-1 in unknowledgeable adolescents vs. 4.26 L·week-1 in adolescents who underestimated, 3.73 L·week-1 in adolescents who overestimated, and 3.64 L·week-1 in adolescents who correctly responded on the energy expenditure required to eliminate an SSB unit, p = 0.033). To conclude, community-based health promotion strategies should (1) focus on the physical effort needed to negate SSB consumption rather than the nutritional energy from SSB units and (2) highlight how to achieve sustainable lifestyles and provide tools for greater understanding and positive action.

Nutrition behaviors and sociodemographic factors associated with overweight in the multi-ethnic adolescents of New Caledonia.

Objectives: New Caledonia is a multi-ethnic French territory in the Pacific, characterized by communities with widely varying nutritional habits. Little is currently known about adolescent food behaviors and habits and their association with overweight. This study therefore determined the sociodemographic factors and food behaviors associated with overweight and underweight in this population, as well as the factors associated with skipping breakfast. Methods: A cross-sectional survey was conducted among New Caledonian adolescents using a self-administered questionnaire; anthropometric measurements were also taken. Weight status was determined using international cutoffs, and the factors associated with overweight and underweight were identified with multiple logistic regression analysis. The factors associated with breakfast skipping were also determined. Results: Skipping breakfast, being Melanesian, living in a rural area and having low economic status were positively associated with overweight in these adolescents. Skipping breakfast was relatively infrequent, reported by 18% and 13% of the males and females, respectively. Logistic regression models found that the main factors associated with breakfast consumption habits were gender, weight status and ethnicity. Conclusions: Several factors are associated with overweight status in New Caledonian adolescents. Breakfast education should be improved for adolescents living in rural areas and from low socioeconomic status.

Potential for waist-to-height ratio to detect overfat adolescents from a Pacific Island, even those within the normal BMI range.

INTRODUCTION: Waist-to-height ratio (WHtR) is a simple anthropometric proxy for central body fat; it is easy to use from a health education perspective. A WHtR value >0.5 has been proposed as a first level indicator of health risk. The first aim of this study was to compare WHtR with values based on body mass index (BMI) in their prediction of the percentage of body fat (%BF) in a multi-ethnic population of adolescents from New-Caledonia (age 11-16year). Secondly, to see whether WHtR >0.5 could be used to detect overfat subjects whose BMI was in the normal range. MATERIALS AND METHODS: Body fat percentage (%BF, based on skinfold measurements), BMI and WHtR were calculated for New Caledonian adolescents from different ethnic backgrounds. The relationship between %BF, BMI and WHtR was determined using quadratic models and from linear regression equations. The sensitivity and specificity of WHtR for detecting overfat adolescents (%BF >25% in boys and >30% in girls) were assessed and compared with those from the BMI-based classification. RESULTS: WHtR showed better correlation with %BF than BMI-based measurements. WHtR >0.5 was also more accurate than BMI in detecting overfat adolescents. Moreover, using this boundary value, 8% of adolescents in the normal BMI range were shown to be over-fat. CONCLUSIONS: WHtR is a good anthropometric proxy to detect overfat adolescents. Detecting overfat adolescents within the normal BMI range is particularly important for preventing non communicable diseases. We therefore recommend using WHtR for health education programs in the Pacific area and more generally.

Self-Reported Height and Weight in Oceanian School-Going Adolescents and Factors Associated With Errors.

We examined the accuracy of self-reported weight and height in New Caledonian school-going adolescents. Self-reported and measured height and weight data were collected from 665 adolescents of New Caledonia and were then compared. Multivariable logistic regressions identified the factors associated with inaccurate self-reports. Sensitivity and specificity of self-reported body mass index values to detect overweight or obesity were evaluated. Self-reported weight was significantly lower than measured weight (boys, -3.56 kg; girls, -3.13 kg). Similar results were found for height (boys, -2.51 cm; girls, -3.23 cm). Multiple regression analyses indicated that the difference between self-reported and measured height was significantly associated with ethnicity and pubertal status. Inaccurate self-reported weight was associated with socioeconomic status, place of residence, body-size perception and weight status. Screening accuracy of self-reported body mass index was low, particularly in the Melanesian subgroup. These findings should be considered when overweight is estimated in the Melanesian adolescent population at individual scale.

Misperception of weight status in the pacific: preliminary findings in rural and urban 11- to 16-year-olds of New Caledonia.

BACKGROUND: Adolescent obesity is prevalent in Pacific region ethnic groups (European, Melanesian and Polynesian) living in both urban and rural areas. Although body perception is an important factor of weight gain or loss, little is known about the body self-perceptions of Pacific region adolescents. This study therefore evaluated adolescent perceptions of body weight according to ethnicity (European, Melanesian or Polynesian), socioeconomic status (low, intermediate or high) and living area (rural or urban) in New Caledonia. METHODS: Sociodemographic and anthropomorphic data from 737 adolescents (351 boys and 386 girls) with ages ranging from 11 to 16 years were collected and analysed. The International Obesity Task Force (IOTF) standards were used to define weight status as normal-weight, underweight or overweight/obese. Weight perception was assessed from detailed questionnaires, with adolescents rating their own weight with the following descriptors: 'about the right weight', 'too heavy', or 'too light'. RESULTS: Results showed that only 8.5% of normal-weight adolescents (7% boys and 10% girls) identifying themselves as 'too heavy'. Normal-weight Melanesian adolescents were less likely than their European counterparts to assess themselves as too heavy (OR = 0.357). However, half the overweight/obese adolescents underestimated their weight status (53% boys and 48% girls). Weight misperception was associated with ethnicity, socioeconomic status and living area, with gender-specific differences. CONCLUSIONS: The results of this study suggest that these sociodemographic factors should be taken into account when designing public health policies and health education school programmes in New Caledonia and, more broadly, the Pacific region.

Gonadotropin-releasing hormone and the control of gonadotrope function.

Normal gametogenesis and steroidogenesis is highly dependent on the pulsatile release of hypothalamic GnRH that binds high-affinity receptors present at the surface of pituitary gonadotrophs thereby triggering the synthesis and release of the gonadotropins LH and FSH. The mammalian GnRH receptor displays the classical heptahelical structure of G protein-coupled receptors with, however, a unique feature, the lack of a C-terminal tail. Accordingly, it does not desensitise sensu stricto, and internalises very poorly. It is now well established that GnRH stimulation induces the activation of a complex network of transduction pathways involved in the control of gonadotropin release and subunit gene expression. Other authors and ourselves have demonstrated that the GnRH action is associated with an increased complexity regarding gene regulation/cell function. Indeed GnRH affects the GnRH receptor gene itself and a number of additional genes that include some involved in cell signalling and auto-/paracrine regulation. The fact that GnRH regulates the expression of its own receptor, together with a host of other genes typically involved in its signal transduction cascades implies alteration/auto-adaptation in gonadotropic responsiveness. Furthermore, some of these genes respond differentially depending on whether the GnRH stimulation is intermittent or permanent suggesting specific roles in the dual process of activation/desensitisation. Thus, it can be assumed that the importance of pulsatility of GnRH action is closely related to, or dependent on, the inability of the GnRH receptor to desensitise. Moreover, multiple post-receptor events are crucial for both the regulation/plasticity of gonadotropic function and the maintenance of cell integrity.

In vivo modulation of follicle-stimulating hormone release and beta subunit gene expression by activin A and the GnRH agonist buserelin in female rats.

The effects of separate and simultaneous recombinant bovine (rb) activin A and buserelin administration on the FSH release and pituitary FSH beta subunit gene expression in vivo were examined in ovariectomised, estradiol pretreated rats. The animals received a single injection of either rb activin A (50 ng), buserelin (1 micro g) or activin/buserelin (50 ng+1 micro g/0.1 ml PBS) into the jugular vein and were killed 30 min, 1, 3 and 5h later. Activin A stimulated FSH release and effect appeared 1h after injection (168% increase of controls) reaching a maximum at 3h (437% of controls). Activin A and buserelin exerted their effects with a distinct time courses: activin's stimulation was not so rapid when compared with buserelin. The simultaneous administration of rb activin A and buserelin amplified FSH release (118, 309, 1006 and 779% of controls). The low dose of activin A was sufficient to elevate FSH beta mRNA level as early as 3 and 5h after administration (170 and 140%, respectively). Activin plus buserelin stimulation resulted in a higher (340 and 360% of controls) FSH beta gene expression than after their separate administration. These results suggest that activin and buserelin may act independently and synergistically in the regulation of FSH release and beta subunit mRNA level.

Intracerebroventricular infusion of neuropeptide Y up-regulates synthesis and accumulation of luteinizing hormone but not follicle stimulating hormone in the pituitary cells of prepubertal female lambs.

Neuropeptide Y (NPY) is a putative neuroregulator of the reproductive axis in the central nervous system. In this study we evaluated the effects of central infusion of exogenous NPY on the secretory activity of pituitary gonadotrophic cells in prepubertal lambs. Immature female Merino sheep (n=12) were infused of Ringer solution (control) or 50 microg of NPY to the third ventricle for 5 min and then slaughtered 3 h later. Immunoreactive luteinizing hormone (LH) and follicle stimulating hormone (FSH) cells were localised by immunohistochemistry using antibody raised against LHbeta and FSHbeta. Messenger RNA analyses were performed by in situ hybridisation using sense and antisense riboprobes produced from beta subunits of LH and FSH cDNA clones. The results were generated by computer image analysis to determine the area fraction occupied by immunoreactive and/or hybridising cells and optical density for immunostaining and hybridisation signal. LH in the blood plasma was determined by radioimmunoassay. It was found, that in the lambs infused with NPY the area fraction and optical density for immunoreactive LH cells and mRNA LHbeta-expressing cells increased significantly (P<0.001), compared to the vehicle-infused animals. The concentration of LH in the blood plasma did not differ between control and treated groups. The NPY infusions had no effect on the immunoreactivity of FSH cells or on expression of mRNA for FSHbeta. In conclusion we suggest that NPY may be an important component of mechanisms stimulating the synthesis and storage but not the release of LH in the pituitary gonadotrophs from prepubertal female sheep. In addition, this effect is specific for LH, no such effect was apparent on FSH.

Effect of estradiol 17-beta on LH subunits and prolactin mRNAs expression in the pituitary of old female rats.

OBJECTIVES: The aim of the study was to examine susceptibility of the pituitary gland to estrogenic impulse in old, noncycling rats by measurement of steady state level of mRNAs encoding LH subunits a and b and mRNA for PRL. METHODS: 22-month-old rats were ovariectomized and after one week they were subcutaneously implanted with silastic tubing filled with oil or with estradiol 17-beta. Pituitary alpha, LHbeta and PRL mRNAs content and serum LH and PRL concentration was determined. RESULTS: The effect of E (2)treatment was manifested by the significant increase in the weight of the uterus and pituitary gland as well as by elevation of total pituitary RNA (109%, 60% and 78%, respectively; p<0.001). No significant changes (p>0.05) in serum LH concentration were observed, while levels of mRNAs encoding alpha and LH-beta subunits were lowered by 54% (p<0.05) and 96% (p<0.01), respectively, in the rats subjected to E(2) stimuli. No direct correlation between synthesis and release of LH in E(2) treated old rats was observed. The blood PRL concentration and the pituitary level of PRL mRNA increased up to 2,000% and 1,300%, respectively (p<0.001). Spontaneous pituitary adenoma was observed in about 30% of the rats, irrespective of treatment. CONCLUSIONS: These data show that in old rats estrogenic stimulus can effectively diminish both pituitary LH subunits mRNAs as well as stimulate pituitary PRL mRNA level indicating that the E(2)-dependent processes involved in the regulation of corresponding genes are still functional.

FSH beta-subunit gene expression in long-term ovariectomized rat after pulsatile intracerebroventricular microinjections of GnRH.

OBJECTIVES: The purpose of this study was to examine whether in long-term ovariectomized rats direct pulsatile intracerebroventricular microinfusions of GnRH would result in frequency dependent biosynthesis of pituitary FSH beta-subunit mRNA. METHODS: Stainless steel cannula was stereotaxically implanted into the third ventricle of ovariectomized rats. 1 nM of GnRH microinjections were given at frequency 1, 2, 4 pulses/hour during 5 hours. Pituitary FSH beta-subunit mRNA level was determined by Northern-blot and serum FSH concentration was examined by RIA. RESULTS: Exogenous GnRH (1nM) induced a significant increase of pituitary content of FSH beta-subunit mRNA when administered 30 or 60 min intervals over 5 hours to ovariectomized rats. RESULTS: GnRH microinjections given at frequency of 1 pulse/hour were mostly effective resulting both in 85% increase of FSH beta-subunit mRNA level as compared to control as well as a significant (78%) stimulation of FSH release. CONCLUSIONS: our data show that in a long term ovariectomized rats (without steroid and gonadal peptides supplementation) a direct pulsatile intracerebroventricular microinjections of GnRH induce frequency-dependent pituitary FSH beta-subunit mRNA biosynthesis in the same mode as it was reported for gonadectomized and steroid replaced rats. It seems therefore that this method would represent an interesting alternative to the use of classical agents to disconnect, in vivo, the pituitary from hypothalamic GnRH influence. It may also provide a physiological data concerning regulatory aspects of gonadotropin subunits biosynthesis.