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Objective: Differences in the content and distribution of body fat and ectopic lipids may be responsible for ethnic variations in metabolic disease susceptibility. The aim of this study was to examine the ethnic distribution of body fat in two separate UK-based populations., Methods: Anthropometry and body composition were assessed in two separate UK cohorts: the Hammersmith cohort and the UK Biobank, both comprising individuals of South Asian descent (SA), individuals of Afro-Caribbean descent (AC), and individuals of European descent (EUR). Regional adipose tissue stores and liver fat were measured by magnetic resonance techniques., Results: The Hammersmith cohort (n = 747) had a mean (SD) age of 41.1 (14.5) years (EUR: 374 men, 240 women; SA: 68 men, 22 women; AC: 14 men, 29 women), and the UK Biobank (n = 9,533) had a mean (SD) age of 55.5 (7.5) years (EUR: 4,483 men, 4,873 women; SA: 80 men, 43 women, AC: 31 men, 25 women). Following adjustment for age and BMI, no significant differences in visceral adipose tissue or liver fat were observed between SA and EUR individuals in the either cohort., Conclusions: Our data, consistent across two independent UK-based cohorts, present a limited number of ethnic differences in the distribution of body fat depots associated with metabolic disease. These results suggest that the ethnic variation in susceptibility to features of the metabolic syndrome may not arise from differences in body fat., (© 2020 The Authors. Obesity published by Wiley Periodicals LLC on behalf of The Obesity Society (TOS).)

Individual compartments of abdominal adiposity and lipid content within the liver and muscle are differentially associated with metabolic risk factors, obesity and insulin resistance. Subjects with greater intra-abdominal adipose tissue (IAAT) and hepatic fat than predicted by clinical indices of obesity may be at increased risk of metabolic diseases despite their "normal" size. There is a need for accurate quantification of these potentially hazardous depots and identification of novel subphenotypes that recognize individuals at potentially increased metabolic risk. We aimed to calculate a reference range for total and regional adipose tissue (AT) as well as ectopic fat in liver and muscle in healthy subjects. We studied the relationship between age, body-mass, BMI, waist circumference (WC), and the distribution of AT, using whole-body magnetic resonance imaging (MRI), in 477 white volunteers (243 male, 234 female). Furthermore, we used proton magnetic resonance spectroscopy (MRS) to determine intrahepatocellular (IHCL) and intramyocellular (IMCL) lipid content. The anthropometric variable which provided the strongest individual correlation for adiposity and ectopic fat stores was WC in men and BMI in women. In addition, we reveal a large variation in IAAT, abdominal subcutaneous AT (ASAT), and IHCL depots not fully predicted by clinically obtained measurements of obesity and the emergence of a previously unidentified subphenotype. Here, we demonstrate gender- and age-specific patterns of regional adiposity in a large UK-based cohort and identify anthropometric variables that best predict individual adiposity and ectopic fat stores. From these data we propose the thin-on-the-outside fat-on-the-inside (TOFI) as a subphenotype for individuals at increased metabolic risk.

Background: The risk of chronic disease is lower in obese men who are fit and active than obese men who are unfit and inactive., Methods/objectives: Magnetic resonance imaging and spectroscopy were used to assess total and regional adipose tissue in 13 men who were slim, fit and active (the slim-fit), in 12 men who were slim, unfit and inactive (the slim-unfit), in 13 men who were fat, fit and active (the fat-fit) and in 12 men who were fat, unfit and inactive (the fat-unfit), in order to investigate the hypothesis that visceral fat and liver fat are lower in the fat-fit than the fat-unfit. Waist girth was used to distinguish slim men (< or =90 cm) and fat men (> or =100 cm). Maximal oxygen consumption was used to identify fit men (above average for age) and unfit men (average or below for age). Fit men reported at least 60 min of vigorous aerobic activity per week and unfit men reported no regular moderate or vigorous activity in the last 2 years., Results: Total fat was not significantly different in the slim-fit and the slim unfit, but the proportion of internal fat was significantly lower (P<0.05) and the proportion of visceral fat was almost significantly lower (P=0.06) in the slim-fit than all other groups. Total fat was not significantly different in the fat-fit and the fat-unfit, but visceral fat and liver fat were significantly lower in the fat-fit than the fat-unfit (P<0.01). Waist girth and years of exercise explained 84% of the variance in total fat, waist girth and maximal oxygen consumption explained 70% of the variance in visceral fat, and waist girth alone explained 25% of the variance in liver fat., Conclusion: Chronic disease risk may be lower because visceral fat and liver fat are lower in men who are fat, fit and active.

Background: Adipose tissue patterning has a major influence on the risk of developing chronic disease. Environmental influences on both body fat patterning and appetite regulation are not fully understood. This study was performed to investigate the impact of resistant starch (RS) on adipose tissue deposition and central regulation of appetite in mice., Methodology and Principle Findings: Forty mice were randomised to a diet supplemented with either the high resistant starch (HRS), or the readily digestible starch (LRS). Using (1)H magnetic resonance (MR) methods, whole body adiposity, intrahepatocellular lipids (IHCL) and intramyocellular lipids (IMCL) were measured. Manganese-enhanced MRI (MEMRI) was used to investigate neuronal activity in hypothalamic regions involved in appetite control when fed ad libitum. At the end of the interventional period, adipocytes were isolated from epididymal adipose tissue and fasting plasma collected for hormonal and adipokine measurement. Mice on the HRS and LRS diet had similar body weights although total body adiposity, subcutaneous and visceral fat, IHCL, plasma leptin, plasma adiponectin plasma insulin/glucose ratios was significantly greater in the latter group. Adipocytes isolated from the LRS group were significantly larger and had lower insulin-stimulated glucose uptake. MEMRI data obtained from the ventromedial and paraventricular hypothalamic nuclei suggests a satiating effect of the HRS diet despite a lower energy intake., Conclusion and Significance: Dietary RS significantly impacts on adipose tissue patterning, adipocyte morphology and metabolism, glucose and insulin metabolism, as well as affecting appetite regulation, supported by changes in neuronal activity in hypothalamic appetite regulation centres which are suggestive of satiation.

Plasma ghrelin is elevated in Prader-Willi syndrome (PWS). This might contribute to obesity or GH deficiency in such patients. Visceral adiposity and insulin resistance are reduced in PWS, which might lead to hyperghrelinemia. We measured fasting plasma ghrelin in control female (n = 39), PWS female (n = 12), and PWS male (n = 6) adults. In controls and PWS, ghrelin was negatively correlated with visceral adiposity, fasting insulin, and homeostasis model insulin resistance index. There was no significant correlation with serum IGF-I in PWS. In stepwise linear regression, visceral adiposity (P < 0.02) had a stronger inverse correlation with ghrelin than sc fat depots in controls and PWS, possibly through hyperinsulinemia, as the correlations with insulin resistance were even stronger (P < 0.01). PWS females had significantly (P < 0.001) elevated ghrelin (mean +/- SD, 661 +/- 360 pg/ml), compared with both nonobese (363 +/- 163) and obese (191 +/- 66) controls. Ghrelin was increased 3.4- to 3.6-fold in PWS females adjusting for total adiposity, 3.2- to 3.4-fold adjusting for visceral adiposity, and 3.0-fold adjusting for insulin resistance. Fasting plasma glucagon-like peptide-1 was normal in PWS females. The hyperghrelinemia in PWS adults is therefore not solely explained by their reduced visceral adiposity and relative hypoinsulinemia. Its cause and consequences await further elucidation.

Background: Obesity in Prader-Willi syndrome (PWS) may be related to abnormalities in the adipocyte-leptin-hypothalamic pathway and may be exacerbated by reductions in the resting metabolic rate (RMR)., Objective: We compared body composition, body-composition- adjusted RMR, and adiposity-adjusted plasma leptin between women with PWS and control women. We also examined leptin receptor expression in the PWS group., Design: We studied body composition using whole-body magnetic resonance imaging and measured plasma leptin by radioimmunoassay in 45 control women aged 18-56 y and in 13 women with PWS aged 20-38 y. RMR was measured by indirect calorimetry in 41 control women and in 8 women with PWS. Age, body composition, and regional adipose tissue (AT) depots were corrected for by multiple regression analysis. Messenger RNA expression of the leptin receptor was examined by reverse transcriptase-polymerase chain reaction in lymphocytes., Results: In the PWS group, fat mass was greater after correction for fat-free mass, and RMR was normal after correction for both fat-free mass and fat mass. Leptin was influenced primarily by subcutaneous AT volume in both subject groups. Leptin concentrations were not significantly different between the 2 groups after adjustment for age and AT content or distribution. Full-length leptin receptor messenger RNA was expressed in the lymphocytes of the PWS group., Conclusions: Differences in RMR in women with PWS are explained by abnormal body composition, suggesting that energy expenditure is normal at the tissue level in PWS. There is no evidence that defective leptin production causes obesity in PWS, and leptin receptor deficiency is not a primary consequence of the gene defects leading to leptin resistance.

Visceral obesity is detrimental to health, but the mechanisms controlling body fat distribution are not fully understood. In premenopausal adult females (30 nonobese, 14 obese [body mass index >30 kg/m(2)]), variance in fasting insulin, glucose, insulin/glucose ratio, C-peptide/insulin ratio, triglycerides, and high-density lipoprotein/low-density lipoprotein-cholesterol ratio, were independently influenced by visceral but not total sc or abdominal sc adipose tissue, as measured by whole-body magnetic resonance imaging. Adult females with Prader-Willi syndrome (n = 13) had significantly reduced visceral adiposity, compared with obese controls (visceral/total sc adipose tissue ratio: 0.067 +/- 0.017 vs. 0.108 +/- 0.021), independent of their total adiposity (P < 0.001), or use of exogenous sex steroids. This is in contrast to that expected by their physical inactivity, hypogonadism, adult GH deficiency, and psychiatric problems. Females with Prader-Willi syndrome not receiving sex steroids (n = 8) had significantly reduced fasting insulin, insulin/glucose ratio, and triglycerides and increased C-peptide/insulin ratio, compared with obese controls, adjusting for total (P < 0.05) but not visceral adiposity (P = 0.3-0.6), supporting their association. The cause of the reduced visceral adiposity in Prader-Willi syndrome may reflect novel hormonal, hypothalamic, and/or genetic influences on body fat distribution.

The aim of this study was to use whole-body magnetic resonance imaging (MRI) together with biochemical and anthropometric measurements to study the influence of regular moderate exercise with no dietary intervention on adipose tissue distribution in nonobese healthy women. We found significant decreases in both total (28.86+/-2.24 vs. 27.00+/-2.27 liters, P < 0.05) and regional fat depots (visceral fat: 1.68+/-0.21 vs. 1.26+/-0.18 liters, P < 0.01) using whole-body MRI despite no significant change in body weight, body mass index, or the waist-to-hip ratio. Interestingly, no changes in body fat content were found using anthropometry or impedance. There was a significant increase in high density lipoprotein cholesterol (1.58+/-0.06 vs. 1.66+/-0.08 mmol/L P < 0.02) following exercise although there were no changes in other blood lipids such as triglycerides. In summary, moderate aerobic exercise over a period of 6 mon resulted in a preferential loss in visceral fat in nonobese healthy women, and this may help to explain some of the health benefits associated with regular and moderate physical activity.

In this study we assessed different magnetic resonance imaging (MRI) scanning regimes and examined some of the assumptions commonly made for measuring body fat content by MRI. Whole body MRI was used to quantify and study different body fat depots in 67 women. The whole body MRI results showed that there was a significant variation in the percentage of total internal, as well as visceral, adipose tissue across a range of adiposity, which could not be predicted from total body fat and/or subcutaneous fat. Furthermore, variation in the amount of total, subcutaneous, and visceral adipose tissue was not related to standard anthropometric measurements such as skinfold measurements, body mass index, and waist-to-hip ratio. Finally, we show for the first time subjects with a percent body fat close to the theoretical maximum (68%). This study demonstrates that the large variation in individual internal fat content cannot be predicted from either indirect methods or direct imaging techniques, such as MRI or computed tomography, on the basis of a single-slice sampling strategy.