Validität der Quantitativen Magnetresonanz-Technologie(QMR)zur Bestimmung der Körperzusammensetzung bei Erwachsenen

Die Quantitative Magnetresonanz (QMR)-Technologie zur Messung der Körperzusammensetzung ist im Bereich von tierexperimentellen Studien längst etabliert. Es gibt jedoch bislang nur wenige Untersuchungen zur Validität der Methode beim Menschen. Die Ergebnisse der Dissertation zeigen, dass QMR eine valide Methode zur nicht invasiven und präzisen Messung der Körperzusammensetzung ist, deren systematischer Fehler im Vergleich zu anderen Referenzmethoden (DXA, Deuteriumdilution, Densitometrie) vergleichbar oder sogar geringer ist. Eine Unterschätzung der FM ist jedoch möglich. Diese begrenzt den Einsatz der Methode für Messungen der Energiebilanz obwohl die hohe Präzision der Messung den Nachweis kleiner Veränderungen der Körperzusammensetzung ermöglicht

‘Functional’ body composition: differentiating between benign and non-benign obesity

Recent body composition analyses, together with assessments of insulin resistance, aerobic fitness, and intima-media thickness of the common carotid artery, have shown that metabolically-benign obese subjects have a similar BMI, waist circumference, and subcutaneous abdominal fat compared with non-metabolically-benign obese subjects. Research has suggested that 25-30% of the obese population do not need either treatment or prevention of secondary disorders. Therefore, assessment of functional body composition should replace nutritional status-based risk assessments (such as the body mass index) in both metabolic research and clinical decision making. The concept of ‘functional’ body composition gives us a more sophisticated view on nutritional status, metabolism, endocrinology, and diseases. Knowledge of detailed body composition enables characterization of biomedical traits which will give functional evidence relating genetic variants

Ultra-processed food consumption and the risk of non-alcoholic fatty liver disease—What are the proposed mechanisms?

A high consumption of ultra-processed food (UPF) is a hallmark of Western diets that has been related to increased risk of non-communicable diseases. As an underlying mechanism, UPF may promote non-alcoholic fatty liver disease (NAFLD) which is a key driver of metabolic impairment with extra-hepatic manifestations like type 2 diabetes, cardiovascular disease, chronic kidney disease, and osteoporosis among others. The present review provides an overview of UPF properties that may promote NAFLD and are thus potential targets for reformulation of UPF. Such approaches should address improvements in the quality of carbohydrates and fat, changes in food texture that lower eating rate as well as ingredients that prevent excess caloric intake or avoid dysbiosis and leaky gut syndrome. Promising strategies are enrichment with fiber, prebiotics, phytochemicals, and protein with a concurrent reduction in glycemic load, energy density, saturated fatty acids (FA; SFA), emulsifiers, fructose, and non-caloric sweeteners. Future studies are needed to examine the interactive and protective effects of such modifications in the composition of UPF on prevention and treatment of NAFLD

Recent advances in understanding body weight homeostasis in humans [version 1; referees: 4 approved]

Presently, control of body weight is assumed to exist, but there is no consensus framework of body weight homeostasis. Three different models have been proposed, with a “set point” suggesting (i) a more or less tight and (ii) symmetric or asymmetric biological control of body weight resulting from feedback loops from peripheral organs and tissues (e.g. leptin secreted from adipose tissue) to a central control system within the hypothalamus. Alternatively, a “settling point” rather than a set point reflects metabolic adaptations to energy imbalance without any need for feedback control. Finally, the “dual intervention point” model combines both paradigms with two set points and a settling point between them. In humans, observational studies on large populations do not provide consistent evidence for a biological control of body weight, which, if it exists, may be overridden by the influences of the obesogenic environment and culture on personal behavior and experiences. To re-address the issue of body weight homeostasis, there is a need for targeted protocols based on sound concepts, e.g. lean rather than overweight subjects should be investigated before, during, and after weight loss and weight regain. In addition, improved methods and a multi-level–multi-systemic approach are needed to address the associations (i) between masses of individual body components and (ii) between masses and metabolic functions in the contexts of neurohumoral control and systemic effects. In the future, simplifications and the use of crude and non-biological phenotypes (i.e. body mass index and waist circumference) should be avoided. Since changes in body weight follow the mismatch between tightly controlled energy expenditure at loosely controlled energy intake, control (or even a set point) is more likely to be about energy expenditure rather than about body weight itself

Impact of Protein Intake during Weight Loss on Preservation of Fat-Free Mass, Resting Energy Expenditure, and Physical Function in Overweight Postmenopausal Women: A Randomized Controlled Trial

Introduction: Weight loss in old age increases the risk of sarcopenia caused by the age-related reduction of fat-free mass (FFM). Due to the strong correlation between FFM and resting energy expenditure (REE), the maintenance of this must also be considered. Besides, the physical function (PF) must be maintained. Objective: The impact of protein intake on changes in FFM, REE, and PF during weight loss in overweight postmenopausal women was investigated. Methods: Fifty-four postmenopausal women (BMI 30.9 ± 3.4; age 59 ± 7 years) were randomized into 2 groups receiving energy-restricted diets with either 0.8 g (normal protein; NP) or 1.5 g protein/kg body weight (high protein; HP) for 12 weeks, followed by a 6-month follow-up phase with an ad libitum food intake. FFM, REE, and PF (strength, endurance, and balance) were measured at baseline, after weight loss, and after follow-up. Results: Forty-six women completed the weight loss intervention and 29 were followed up. The weight loss was –4.6 ± 3.6 kg (HP) and –5.2 ± 3.4 kg (NP; both p < 0.001) and the weight regain during follow-up was 1.3 ± 2.8 kg (HP; p = 0.03) and 0.4 ± 2.5 kg (NP; p = 0.39), with no differences between groups. Similar decreases in FFM (–0.9 ± 1.1 [HP] vs. –1.0 ± 1.3 kg [NP]) and REE (–862 ± 569 [HP] vs. –1,000 ± 561 kJ [NP]; both p < 0.001) were observed in both groups. During follow-up, no changes in FFM were detected in either group, whereas in the NP group the REE increased again (+138 ± 296; p = 0.02). The main determinants of FFM loss were the energy deficit and the speed of weight loss. In the NP group, the Short Physical Performance Battery score improved with weight loss (+0.6 ± 0.8; p < 0.001) and handgrip strength decreased (–1.7 ± 3.4 kg; p < 0.001), whereas no changes were observed in the HP group. Conclusions: An HP weight-loss diet without exercise had no impact on preservation of FFM and REE but may help to maintain muscle strength in postmenopausal women

Relationship between Birth Weight, Early Growth Rate, and Body Composition in 5- to 7-Year-Old Children

Background: Programing of body composition during intrauterine growth may contribute to the higher risk for cardio-metabolic disease in individuals born small or large for gestational age (SGA, LGA). Compensations of intrauterine growth by catch-up or catch-down postnatal growth may lead to adverse consequences like a thin-fat phenotype. Methods: The impact of (i) birth weight as well as (ii) the interaction between birth weight and catch-up or catch-down growth during the first 2 years of life on fat-free mass index (FFMI) and fat mass index (FMI) in 3,204 5–7-year-old children were investigated using Hattori’s body composition chart. Body composition results were compared to appropriate for gestational age (AGA) birth weight with the same body mass index (BMI). Results: In total, 299 children at age 5–7 years were categorized as SGA, 2,583 as AGA, and 322 as LGA. When compared to AGA-children, BMI at 5–7 years of age was higher in LGA-children (15.5 vs. 16.2 kg/m2; p < 0.001) but not different in SGA-children. Compared to AGA with the same BMI, LGA was associated with higher FMI and a lower FFMI in 5–7-year-old girls. This phenotype was also seen for both sexes with catch-down growth during the first 2 years of life whereas catch-up growth prevented the higher FMI and lower FFMI per BMI. By contrast, SGA was associated with a higher FFMI and lower FMI in 5–7-year-old boys compared to AGA boys with the same BMI. This phenotype was also seen with catch-down growth in both genders whereas catch-up growth in girls led to more gain in FMI per BMI. Conclusion: LGA with a compensatory catch-down postnatal growth may be a risk factor for the development of disproportionate gain in fat over lean mass whereas SGA with a catch-down postnatal growth seems to favor the subsequent accretion of lean over fat mass. A higher propensity of lean mass accretion during postnatal growth in boys compared to girls explains sex differences in these phenotypes

Analysis of the adiponectin paradox in healthy older people

Background It remains unknown why adiponectin levels are associated with poor physical functioning, skeletal muscle mass and increased mortality in older populations. Methods In 190 healthy adults (59-86 years, BMI 17-37 kg/m2 , 56.8% female), whole body skeletal muscle mass (normalized by height, SMI, kg/m2 ), muscle and liver fat were determined by magnetic resonance imaging. Bone mineral content (BMC) and density (BMD) were assessed by dual X-ray absorptiometry (n = 135). Levels of insulin-like growth factor 1 (IGF-1), insulin, inflammation markers, leptin and fibroblast growth factor 21 were measured as potential determinants of the relationship between adiponectin and body composition. Results Higher adiponectin levels were associated with a lower SMI (r = -0.23, P < 0.01), BMC (r = -0.17, P < 0.05) and liver fat (r = -0.20, P < 0.05) in the total population and with higher muscle fat in women (r = 0.27, P < 0.01). By contrast, IGF-1 showed positive correlations with SMI (r = 0.33), BMD (r = 0.37) and BMC (r = 0.33) (all P < 0.01) and a negative correlation with muscle fat (r = -0.17, P < 0.05). IGF-1 was negatively associated with age (r = -0.21, P < 0.01) and with adiponectin (r = -0.15, P < 0.05). Stepwise regression analyses revealed that IGF-1, insulin and leptin explained 18% of the variance in SMI, and IGF-1, leptin and age explained 16% of the variance in BMC, whereas adiponectin did not contribute to these models. Conclusions Associations between higher adiponectin levels and lower muscle or bone mass in healthy older adults may be explained by a decrease in IGF-1 with increasing adiponectin levels

Boron Contents of German Mineral and Medicinal Waters and Their Bioavailability in Drosophila melanogaster and Humans

Scope Boron is a trace element that naturally occurs in soil, making mineral and medicinal water important contributors to overall intake. Thus, in a systematic screening, the mean boron concentrations of 381 German mineral and medicinal waters are determined. Methods and results Boron concentrations in mineral and medicinal waters are analyzed by inductively coupled mass spectrometry (ICP-MS). Highest boron values find in waters from the southwest of Germany. The boron content of the waters is positively correlated with the concentration of most other analyzed bulk elements, including calcium, potassium, magnesium, and sodium. Mineral waters with either low (7.9 µg L-1 ), medium (113.9 µg L-1 ), or high (2193.3 µg L-1 ) boron content are chosen for boron exposure experiments in fruit flies (Drosophila melanogaster) and humans. In flies, boron-rich mineral water significantly increases boron accumulation, with the accumulation predominantly occurring in the exoskeleton. In humans, serum boron and 24-h urinary boron excretion significantly increase only in response to the intake of boron-rich mineral water. Conclusion Overall, the current data demonstrate that mineral and medicinal waters vary substantially in the content of boron and that boron-rich mineral water can be used to elevate the boron status, both in flies and humans

Effect of Constitution on Mass of Individual Organs and Their Association with Metabolic Rate in Humans—A Detailed View on Allometric Scaling

Resting energy expenditure (REE)-power relationships result from multiple underlying factors including weight and height. In addition, detailed body composition, including fat free mass (FFM) and its components, skeletal muscle mass and internal organs with high metabolic rates (i.e. brain, heart, liver, kidneys), are major determinants of REE. Since the mass of individual organs scales to height as well as to weight (and, thus, to constitution), the variance in these associations may also add to the variance in REE. Here we address body composition (measured by magnetic resonance imaging) and REE (assessed by indirect calorimetry) in a group of 330 healthy volunteers differing with respect to age (17–78 years), sex (61% female) and BMI (15.9–47.8 kg/m2). Using three dimensional data interpolation we found that the inter-individual variance related to scaling of organ mass to height and weight and, thus, the constitution-related variances in either FFM (model 1) or kidneys, muscle, brain and liver (model 2) explained up to 43% of the inter-individual variance in REE. These data are the first evidence that constitution adds to the complexity of REE. Since organs scale differently as weight as well as height the “fit” of organ masses within constitution should be considered as a further trait

The case of GWAS of obesity: does body weight control play by the rules?

As yet, genome-wide association studies (GWAS) have not added much to our understanding of the mechanisms of body weight control and of the etiology of obesity. This shortcoming is widely attributed to the complexity of the issues. The appeal of this explanation notwithstanding, we surmise that (i) an oversimplification of the phenotype (namely by the use of crude anthropometric traits) and (ii) a lack of sound concepts of body weight control and, thus, a lack of a clear research focus have impeded better insights most. The idea of searching for polygenetic mechanisms underlying common forms of obesity was born out of the impressive findings made for monogenetic forms of extreme obesity. In the case of common obesity, however, observational studies on normal weight and overweight subjects never provided any strong evidence for a tight internal control of body weight. In addition, empirical studies of weight changes in normal weight and overweight subjects revealed an intra- individual variance that was similar to inter-individual variance suggesting the absence of tight control of body weight. Not least, this lack of coerciveness is reflected by the present obesity epidemic. Finally, data on detailed body composition highlight that body weight is too heterogeneous a phenotype to be controlled as a single entity. In summary GWAS of obesity using crude anthropometric traits have likely been misled by popular heritability estimates that may have been inflated in the first place. To facilitate more robust and useful insights into the mechanisms of internal control of human body weight and, consequently, the genetic basis of obesity, we argue in favor of a broad discussion between scientists from the areas of integrative physiologic and of genomics. This discussion should aim at better conceived studies employing biologically more meaningful phenotypes based on in depth body composition analysis. To advance the scientific community—including the editors of our top journals—needs a re-launch of future GWAS of obesity