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Abstract ObjectivesStudies suggest that living at high altitude decreases obesity risk, but this research is limited to single‐country analyses. We examine the relationship between altitude and body mass index (BMI) among women living in a diverse sample of low‐ and middle‐income countries. Materials and MethodsUsing Demographic and Health Survey data from 1 583 456 reproductive age women (20–49 years) in 54 countries, we fit regression models predicting BMI and obesity by altitude controlling for a range of demographic factors—age, parity, breastfeeding status, wealth, and education. ResultsA mixed‐effects model with country‐level random intercepts and slopes predicts an overall −0.162 kg/m2(95% CI −0.220, −0.104) reduction in BMI and lower odds of obesity (OR 0.90, 95% CI 0.87, 0.95) for every 200 m increase in altitude. However, countries vary dramatically in whether they exhibit a negative or positive association between altitude and BMI (34 countries negative, 20 positive). Mixed findings also arise when examining odds of obesity. DiscussionWe show that past findings of declining obesity risk with altitude are not universal. Increasing altitude predicts slightly lower BMIs at the global level, but the relationship within individual countries varies in both strength and direction.
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Sparse System Identification of Leptin Dynamics in Women With Obesity
The prevalence of obesity is increasing around the world at an alarming rate. The interplay of the hormone leptin with the hypothalamus-pituitary-adrenal axis plays an important role in regulating energy balance, thereby contributing to obesity. This study presents a mathematical model, which describes hormonal behavior leading to an energy abnormal equilibrium that contributes to obesity. To this end, we analyze the behavior of two neuroendocrine hormones, leptin and cortisol, in a cohort of women with obesity, with simplified minimal state-space modeling. Using a system theoretic approach, coordinate descent method, and sparse recovery, we deconvolved the serum leptin-cortisol levels. Accordingly, we estimate the secretion patterns, timings, amplitudes, number of underlying pulses, infusion, and clearance rates of hormones in eighteen premenopausal women with obesity. Our results show that minimal state-space model was able to successfully capture the leptin and cortisol sparse dynamics with the multiple correlation coefficients greater than 0.83 and 0.87, respectively. Furthermore, the Granger causality test demonstrated a negative prospective predictive relationship between leptin and cortisol, 14 of 18 women. These results indicate that increases in cortisol are prospectively associated with reductions in leptin and vice versa, suggesting a bidirectional negative inhibitory relationship. As dysregulation of leptin may result in an abnormality in satiety and thereby associated to obesity, the investigation of leptin-cortisol sparse dynamics may offer a better diagnostic methodology to improve better treatments plans for individuals with obesity.
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- PAR ID:
- 10322331
- Date Published:
- Journal Name:
- Frontiers in Endocrinology
- Volume:
- 13
- ISSN:
- 1664-2392
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3389/fendo.2022.769951
