Rising rural body-mass index is the main driver of the global obesity epidemic in adults

Body-mass index (BMI) has increased steadily in most countries in parallel with a rise in the proportion of the population who live in cities(.)(1,2) This has led to a widely reported view that urbanization is one of the most important drivers of the global rise in obesity(3-6). Here we use 2,009 population-based studies, with measurements of height and weight in more than 112 million adults, to report national, regional and global trends in mean BMI segregated by place of residence (a rural or urban area) from 1985 to 2017. We show that, contrary to the dominant paradigm, more than 55% of the global rise in mean BMI from 1985 to 2017-and more than 80% in some low- and middle-income regions-was due to increases in BMI in rural areas. This large contribution stems from the fact that, with the exception of women in sub-Saharan Africa, BMI is increasing at the same rate or faster in rural areas than in cities in low- and middle-income regions. These trends have in turn resulted in a closing-and in some countries reversal-of the gap in BMI between urban and rural areas in low- and middle-income countries, especially for women. In high-income and industrialized countries, we noted a persistently higher rural BMI, especially for women. There is an urgent need for an integrated approach to rural nutrition that enhances financial and physical access to healthy foods, to avoid replacing the rural undernutrition disadvantage in poor countries with a more general malnutrition disadvantage that entails excessive consumption of low-quality calories.Peer reviewe

Height and body-mass index trajectories of school-aged children and adolescents from 1985 to 2019 in 200 countries and territories: a pooled analysis of 2181 population-based studies with 65 million participants

Summary Background Comparable global data on health and nutrition of school-aged children and adolescents are scarce. We aimed to estimate age trajectories and time trends in mean height and mean body-mass index (BMI), which measures weight gain beyond what is expected from height gain, for school-aged children and adolescents. Methods For this pooled analysis, we used a database of cardiometabolic risk factors collated by the Non-Communicable Disease Risk Factor Collaboration. We applied a Bayesian hierarchical model to estimate trends from 1985 to 2019 in mean height and mean BMI in 1-year age groups for ages 5–19 years. The model allowed for non-linear changes over time in mean height and mean BMI and for non-linear changes with age of children and adolescents, including periods of rapid growth during adolescence. Findings We pooled data from 2181 population-based studies, with measurements of height and weight in 65 million participants in 200 countries and territories. In 2019, we estimated a difference of 20 cm or higher in mean height of 19-year-old adolescents between countries with the tallest populations (the Netherlands, Montenegro, Estonia, and Bosnia and Herzegovina for boys; and the Netherlands, Montenegro, Denmark, and Iceland for girls) and those with the shortest populations (Timor-Leste, Laos, Solomon Islands, and Papua New Guinea for boys; and Guatemala, Bangladesh, Nepal, and Timor-Leste for girls). In the same year, the difference between the highest mean BMI (in Pacific island countries, Kuwait, Bahrain, The Bahamas, Chile, the USA, and New Zealand for both boys and girls and in South Africa for girls) and lowest mean BMI (in India, Bangladesh, Timor-Leste, Ethiopia, and Chad for boys and girls; and in Japan and Romania for girls) was approximately 9–10 kg/m2. In some countries, children aged 5 years started with healthier height or BMI than the global median and, in some cases, as healthy as the best performing countries, but they became progressively less healthy compared with their comparators as they grew older by not growing as tall (eg, boys in Austria and Barbados, and girls in Belgium and Puerto Rico) or gaining too much weight for their height (eg, girls and boys in Kuwait, Bahrain, Fiji, Jamaica, and Mexico; and girls in South Africa and New Zealand). In other countries, growing children overtook the height of their comparators (eg, Latvia, Czech Republic, Morocco, and Iran) or curbed their weight gain (eg, Italy, France, and Croatia) in late childhood and adolescence. When changes in both height and BMI were considered, girls in South Korea, Vietnam, Saudi Arabia, Turkey, and some central Asian countries (eg, Armenia and Azerbaijan), and boys in central and western Europe (eg, Portugal, Denmark, Poland, and Montenegro) had the healthiest changes in anthropometric status over the past 3·5 decades because, compared with children and adolescents in other countries, they had a much larger gain in height than they did in BMI. The unhealthiest changes—gaining too little height, too much weight for their height compared with children in other countries, or both—occurred in many countries in sub-Saharan Africa, New Zealand, and the USA for boys and girls; in Malaysia and some Pacific island nations for boys; and in Mexico for girls. Interpretation The height and BMI trajectories over age and time of school-aged children and adolescents are highly variable across countries, which indicates heterogeneous nutritional quality and lifelong health advantages and risks

Minimal information for studies of extracellular vesicles (MISEV2023): From basic to advanced approaches

Extracellular vesicles (EVs), through their complex cargo, can reflect the state of their cell of origin and change the functions and phenotypes of other cells. These features indicate strong biomarker and therapeutic potential and have generated broad interest, as evidenced by the steady year-on-year increase in the numbers of scientific publications about EVs. Important advances have been made in EV metrology and in understanding and applying EV biology. However, hurdles remain to realising the potential of EVs in domains ranging from basic biology to clinical applications due to challenges in EV nomenclature, separation from non-vesicular extracellular particles, characterisation and functional studies. To address the challenges and opportunities in this rapidly evolving field, the International Society for Extracellular Vesicles (ISEV) updates its 'Minimal Information for Studies of Extracellular Vesicles', which was first published in 2014 and then in 2018 as MISEV2014 and MISEV2018, respectively. The goal of the current document, MISEV2023, is to provide researchers with an updated snapshot of available approaches and their advantages and limitations for production, separation and characterisation of EVs from multiple sources, including cell culture, body fluids and solid tissues. In addition to presenting the latest state of the art in basic principles of EV research, this document also covers advanced techniques and approaches that are currently expanding the boundaries of the field. MISEV2023 also includes new sections on EV release and uptake and a brief discussion of in vivo approaches to study EVs. Compiling feedback from ISEV expert task forces and more than 1000 researchers, this document conveys the current state of EV research to facilitate robust scientific discoveries and move the field forward even more rapidly

Heterogeneous contributions of change in population distribution of body mass index to change in obesity and underweight NCD Risk Factor Collaboration (NCD-RisC)

From 1985 to 2016, the prevalence of underweight decreased, and that of obesity and severe obesity increased, in most regions, with significant variation in the magnitude of these changes across regions. We investigated how much change in mean body mass index (BMI) explains changes in the prevalence of underweight, obesity, and severe obesity in different regions using data from 2896 population-based studies with 187 million participants. Changes in the prevalence of underweight and total obesity, and to a lesser extent severe obesity, are largely driven by shifts in the distribution of BMI, with smaller contributions from changes in the shape of the distribution. In East and Southeast Asia and sub-Saharan Africa, the underweight tail of the BMI distribution was left behind as the distribution shifted. There is a need for policies that address all forms of malnutrition by making healthy foods accessible and affordable, while restricting unhealthy foods through fiscal and regulatory restrictions

Diffusion multiple par des cibles élastiques immergées.<br />Propagation d'ondes cohérentes et interactions résonantes.

This work deals with the acoustic scattering by a random distribution of cylindrical shells in a fluid. This studyhas three parts. The first one is about a limited number of shells. A resonant coupling is shown. This coupleinduces a split of the A-wave (Scholte-Stoneley wave) resonances. These splits are experimentally validated.The second part presents two effective media theories: Waterman and Truell's and the Fikioris and Waterman'sone. They consist in the analytic averaging of the scattered field with the positions of shells. The average waveobtained is called the effective or coherent wave. The major difference between these theories is that Fikioris andWaterman take into account the size of the shells whereas, in the Waterman and Truell theory, the radius of theshells tends towards zero. These two theories allow the computation of an effective wave number. The influenceof the resonances of one shell is seen on the effective phase velocity and on the effective attenuation. The resultsof these two theories are compared with the ones of a third theory: the one of Foldy. All these theories givesimilar results for weak concentrations, but, for strong concentrations, the results of the theory of Fikioris andWaterman differ from the others. The study of a slab-like region with randomly placed shells leads to thedetermination of a reflection and a transmission coefficient. These are similar to the ones obtained byconsidering a fluid slab. The analogy between the inhomogeneous medium and a viscous fluid is possible. Theexperimental study of such a medium gives good results for the effective attenuation. The last part deals withinhomogeneous media with the shells replaced by a set of two shells close enough to produce resonant coupling.In this case, an effective wave number is obtained with the Fikioris and Waterman theory. The reflection andtransmission coefficients can be expressed as the ones of a fictitious fluid-like slab for which the phase velocityand the attenuation would be dependent of the direction of propagation.diffuseurs élastiques aléatoirement répartis. Cette étude se compose de trois parties. La première parties'intéresse à un nombre restreint de diffuseurs. Elle a permis de mettre en évidence un phénomène de couplagerésonant entre des diffuseurs cylindriques proches se manifestant par une démultiplication des fréquences derésonances associées à l'onde A (onde de Scholte-Stoneley). Ces démultiplications ont été validéesexpérimentalement. La seconde partie présente deux théories de milieu effectif : celle de Waterman et Truell etcelle de Fikioris et Waterman. La philosophie de ces deux théories est de déterminer l'onde moyenne résultantd'un moyennage sur les positions des diffuseurs. C'est cette onde que l'on appelle onde cohérente. Ces théoriesaboutissent au calcul d'un nombre d'onde effectif caractérisant l'onde cohérente. La différence essentielle entreces deux théories réside dans la prise en compte de la taille des diffuseurs dans celle de Fikioris et Waterman.Les résultats des ces deux théories sont comparés entre eux et avec ceux obtenus par une troisième théorie, cellede Foldy. On note l'influence des fréquences de résonance d'un diffuseur seul sur le nombre d'onde effectif. Lestrois théories donnent des résultats similaires pour de faibles concentrations. Dans le cas de fortes concentrations,les résultats issus de la théorie de Fikioris et Waterman se distinguent de ceux obtenus par les deux autresthéories. Lorsque l'on considère une couche de milieu multi-diffuseur, on peut déterminer des coefficients deréflexion et de transmission s'exprimant formellement comme ceux d'une plaque fluide. Une analogie entre unmilieu multi-diffuseur et un milieu fluide visqueux est possible. L'étude expérimentale menée sur un tel systèmemontre un bon accord avec la théorie en ce qui concerne l'atténuation. La dernière partie de ce documentconsiste en l'étude d'un milieu multi-diffuseur dans lequel les diffuseurs sont anisotropes. Les diffuseurs dumilieu présenté sont constitués de deux diffuseurs cylindriques suffisamment proches pour qu'il y ait couplagerésonant. On peut alors déterminer un nombre d'onde effectif à l'aide de la théorie de Fikioris et Waterman, ainsique des coefficient de réflexion et de transmission. Ces derniers se mettent sous la même forme que ceuxassociés à un milieu fictif de type fluide pour lequel la vitesse de phase et l'atténuation varieraient en fonction dela direction de propagation

Diffusion multiple par des cibles élastiques immergées (propagation d'ondes cohérentes et interactions résonantes)

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