The technology and application of current accelerometer-based devices in physical activity (PA) research allow the capture and storage or transmission of large volumes of raw acceleration signal ...data. These rich data not only provide opportunities to improve PA characterisation, but also bring logistical and analytic challenges. We discuss how researchers and developers from multiple disciplines are responding to the analytic challenges and how advances in data storage, transmission and big data computing will minimise logistical challenges. These new approaches also bring the need for several paradigm shifts for PA researchers, including a shift from count-based approaches and regression calibrations for PA energy expenditure (PAEE) estimation to activity characterisation and EE estimation based on features extracted from raw acceleration signals. Furthermore, a collaborative approach towards analytic methods is proposed to facilitate PA research, which requires a shift away from multiple independent calibration studies. Finally, we make the case for a distinction between PA represented by accelerometer-based devices and PA assessed by self-report.
Rediscovery of cold-activated brown adipose tissue (BAT) in humans has boosted research interest in identifying BAT activators for metabolic benefits. Of particular interest are cytokines capable of ...fat browning. Irisin, derived from FNDC5, is an exercise-induced myokine that drives brown-fat-like thermogenesis in murine white fat. Here we explored whether cold exposure is an afferent signal for irisin secretion in humans and compared it with FGF21, a brown adipokine in rodents. Cold exposure increased circulating irisin and FGF21. We found an induction of irisin secretion proportional to shivering intensity, in magnitude similar to exercise-stimulated secretion. FNDC5 and/or FGF21 treatment upregulated human adipocyte brown fat gene/protein expression and thermogenesis in a depot-specific manner. These results suggest exercise-induced irisin secretion could have evolved from shivering-related muscle contraction, serving to augment brown fat thermogenesis in concert with FGF21. Irisin-mediated muscle-adipose crosstalk may represent a thermogenic, cold-activated endocrine axis that is exploitable in obesity therapeutics development.
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•Shivering stimulates irisin secretion in humans•Nonshivering cold exposure increases FGF21, which may be a brown adipokine•Irisin and/or FGF21 upregulates brown-fat-like program in human adipocytes•Exercise may be a shivering mimic exemplifying muscle-fat thermogenic crosstalk
Lee et al. show that, in humans, cold exposure leading to shivering stimulates production of irisin, an exercise-induced myokine, while nonshivering cold exposure increases FGF21. These results suggest exercise-induced irisin secretion could have evolved from shivering-related muscle contraction, serving to augment brown fat thermogenesis in concert with FGF21.
We investigated whether ultra-processed foods affect energy intake in 20 weight-stable adults, aged (mean ± SE) 31.2 ± 1.6 years and BMI = 27 ± 1.5 kg/m2. Subjects were admitted to the NIH Clinical ...Center and randomized to receive either ultra-processed or unprocessed diets for 2 weeks immediately followed by the alternate diet for 2 weeks. Meals were designed to be matched for presented calories, energy density, macronutrients, sugar, sodium, and fiber. Subjects were instructed to consume as much or as little as desired. Energy intake was greater during the ultra-processed diet (508 ± 106 kcal/day; p = 0.0001), with increased consumption of carbohydrate (280 ± 54 kcal/day; p < 0.0001) and fat (230 ± 53 kcal/day; p = 0.0004), but not protein (−2 ± 12 kcal/day; p = 0.85). Weight changes were highly correlated with energy intake (r = 0.8, p < 0.0001), with participants gaining 0.9 ± 0.3 kg (p = 0.009) during the ultra-processed diet and losing 0.9 ± 0.3 kg (p = 0.007) during the unprocessed diet. Limiting consumption of ultra-processed foods may be an effective strategy for obesity prevention and treatment.
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•20 inpatient adults received ultra-processed and unprocessed diets for 14 days each•Diets were matched for presented calories, sugar, fat, fiber, and macronutrients•Ad libitum intake was ∼500 kcal/day more on the ultra-processed versus unprocessed diet•Body weight changes were highly correlated with diet differences in energy intake
Hall et al. investigated 20 inpatient adults who were exposed to ultra-processed versus unprocessed diets for 14 days each, in random order. The ultra-processed diet caused increased ad libitum energy intake and weight gain despite being matched to the unprocessed diet for presented calories, sugar, fat, sodium, fiber, and macronutrients.
By combining angle-resolved photoemission spectroscopy and quantum oscillation measurements, we performed a comprehensive investigation on the electronic structure of LaSb, which exhibits ...near-quadratic extremely large magnetoresistance (XMR) without any sign of saturation at magnetic fields as high as 40 T. We clearly resolve one spherical and one intersecting-ellipsoidal hole Fermi surfaces (FSs) at the Brillouin zone (BZ) center Γ and one ellipsoidal electron FS at the BZ boundary X. The hole and electron carriers calculated from the enclosed FS volumes are perfectly compensated, and the carrier compensation is unaffected by temperature. We further reveal that LaSb is topologically trivial but shares many similarities with the Weyl semimetal TaAs family in the bulk electronic structure. Based on these results, we have examined the mechanisms that have been proposed so far to explain the near-quadratic XMR in semimetals.
Topological semimetals are characterized by symmetry-protected band crossings, which can be preserved in different dimensions in momentum space, forming zero-dimensional nodal points, one-dimensional ...nodal lines, or even two-dimensional nodal surfaces. Materials harboring nodal points and nodal lines have been experimentally verified, whereas experimental evidence of nodal surfaces is still lacking. Here, using angle-resolved photoemission spectroscopy (ARPES), we reveal the coexistence of Dirac nodal surfaces and nodal lines in the bulk electronic structures of ZrSiS. As compared with previous ARPES studies on ZrSiS, we obtained pure bulk states, which enable us to extract unambiguously intrinsic information of the bulk nodal surfaces and nodal lines. Our results show that the nodal lines are the only feature near the Fermi level and constitute the whole Fermi surfaces. We not only prove that the low-energy quasiparticles in ZrSiS are contributed entirely by Dirac fermions but also experimentally realize the nodal surface in topological semimetals.
Objective
To measure long‐term changes in resting metabolic rate (RMR) and body composition in participants of “The Biggest Loser” competition.
Methods
Body composition was measured by dual energy ...X‐ray absorptiometry, and RMR was determined by indirect calorimetry at baseline, at the end of the 30‐week competition and 6 years later. Metabolic adaptation was defined as the residual RMR after adjusting for changes in body composition and age.
Results
Of the 16 “Biggest Loser” competitors originally investigated, 14 participated in this follow‐up study. Weight loss at the end of the competition was (mean ± SD) 58.3 ± 24.9 kg (P < 0.0001), and RMR decreased by 610 ± 483 kcal/day (P = 0.0004). After 6 years, 41.0 ± 31.3 kg of the lost weight was regained (P = 0.0002), while RMR was 704 ± 427 kcal/day below baseline (P < 0.0001) and metabolic adaptation was −499 ± 207 kcal/day (P < 0.0001). Weight regain was not significantly correlated with metabolic adaptation at the competition's end (r = −0.1, P = 0.75), but those subjects maintaining greater weight loss at 6 years also experienced greater concurrent metabolic slowing (r = 0.59, P = 0.025).
Conclusions
Metabolic adaptation persists over time and is likely a proportional, but incomplete, response to contemporaneous efforts to reduce body weight.
We investigated the fate and rate of stabilization of root vs. residue C and the role of soil aggregates in root- vs. residue-derived C accumulation within long-term conventional (mineral ...fertilizer), low-input (mineral fertilizer and cover crop), and organic (manure and cover crop) cropping systems. Both hairy vetch (Vicia dasycarpa Ten.) roots and residue were 13C labeled in situ and then traced into whole-soil samples and three soil organic matter (SOM) fractions (coarse particulate organic matter CPOM, >250 µm, microaggregates 53–250 µm, and silt and clay <53 µm). At the end of the maize (Zea mays L.) growing season, 52% of the root-derived C was still present in the soil, while only 4% of residue-derived C remained. These results suggest that root C contributes more to overall C stabilization than residue C, which supports a nascent body of research demonstrating greater retention of root-derived than residue-derived C in SOM. The ratio of root- to residue-derived C (an indicator of relative root contribution) was higher in the microaggregates and silt-and-clay fractions than the CPOM of low-input and conventional systems. In contrast, relative root contribution was greater in the whole soil of the organic (6.76) than the conventional (1.43) and low-input cropping systems (3.24), and particularly greater in the CPOM of the organic system (7.53). This trend mirrored long-term soil C stocks across the cropping systems, i.e., organic > low input = conventional, and suggests that the CPOM fraction is pivotal to short-term accumulation of root-derived C and, ultimately, to long-term C sequestration under organic crop management.
Human brown adipose tissue (BAT) can be activated to increase glucose uptake and energy expenditure, making it a potential target for treating obesity and metabolic disease. Data on the functional ...and anatomic characteristics of BAT are limited, however. In 20 healthy young men 12 lean, mean body mass index (BMI) 23.2 ± 1.9 kg/m²; 8 obese, BMI 34.8 ± 3.3 kg/m² after 5 h of tolerable cold exposure, we measured BAT volume and activity by 18F-labeled fluorodeoxyglucose positron emission tomography/computerized tomography (PET/CT). Obese men had less activated BAT than lean men (mean, 130 vs. 334 mL) but more fat in BAT-containing depots (mean, 1,646 vs. 855 mL) with a wide range (0.1–71%) in the ratio of activated BAT to inactive fat between individuals. Six anatomic regions had activated BAT—cervical, supraclavicular, axillary, mediastinal, paraspinal, and abdominal—with 67 ± 20% of all activated BAT concentrated in a continuous fascial layer comprising the first three depots in the upper torso. These nonsubcutaneous fat depots amounted to 1.5% of total body mass (4.3% of total fat mass), and up to 90% of each depot could be activated BAT. The amount and activity of BAT was significantly influenced by region of interest selection methods, PET threshold criteria, and PET resolutions. The present study suggests that active BAT can be found in specific adipose depots in adult humans, but less than one-half of the fat in these depots is stimulated by acute cold exposure, demonstrating a previously underappreciated thermogenic potential.
In rodents, brown adipose tissue (BAT) regulates cold- and diet-induced thermogenesis (CIT; DIT). Whether BAT recruitment is reversible and how it impacts on energy metabolism have not been ...investigated in humans. We examined the effects of temperature acclimation on BAT, energy balance, and substrate metabolism in a prospective crossover study of 4-month duration, consisting of four consecutive blocks of 1-month overnight temperature acclimation (24 °C month 1 → 19 °C month 2 → 24 °C month 3 → 27 °C month 4) of five healthy men in a temperature-controlled research facility. Sequential monthly acclimation modulated BAT reversibly, boosting and suppressing its abundance and activity in mild cold and warm conditions (P < 0.05), respectively, independent of seasonal fluctuations (P < 0.01). BAT acclimation did not alter CIT but was accompanied by DIT (P < 0.05) and postprandial insulin sensitivity enhancement (P < 0.05), evident only after cold acclimation. Circulating and adipose tissue, but not skeletal muscle, expression levels of leptin and adiponectin displayed reciprocal changes concordant with cold-acclimated insulin sensitization. These results suggest regulatory links between BAT thermal plasticity and glucose metabolism in humans, opening avenues to harnessing BAT for metabolic benefits.
College-educated workers entering the labor market in 1940 experienced a 4-fold increase in their labor earnings between the ages of 25 and 55; in contrast, the increase was 2.6-fold for those ...entering the market in 1980. For workers without a college education these figures are 3.6-fold and 1.5-fold, respectively. Why are earnings profiles flatter for recent cohorts? We build a parsimonious model of schooling and human capital accumulation on the job, and calibrate it to earnings statistics of workers from the 1940 cohort. The model accounts for 99% of the flattening of earnings profiles for workers with a college education between the 1940 and the 1980 cohorts (52% for workers without a college education). The flattening in our model results from a single exogenous factor: the increasing price of skills. The higher skill price induces (i) higher college enrollment for recent cohorts and thus a change in the educational composition of workers and (ii) higher human capital at the start of work life for college-educated workers in the recent cohorts, which implies lower earnings growth over the life cycle.
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