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Sage — A Metabolic Hypothesis of Brown Fat

Specialized Mitochondrial Capacity, Controlled Uncoupling, Energy Flux, Nocturnal Quality Control, and Ancestral Circadian Entrainment

Disclaimer. This is a hypothesis essay grounded in mechanistic evidence, clinical observation, first-principles reasoning, and integration with prior essays in this metabolic hypothesis series. It is not medical advice, does not diagnose or treat any disease, and should not be used to replace individualized clinical care. Interventions that alter diet, temperature exposure, exercise, or fasting can interact with medications and underlying conditions; readers should consult qualified physicians before making changes. Individual responses vary. The large observational associations discussed here do not prove causation. The nocturnal quality-control hypothesis advanced below is explicitly framed as testable.

Dashboard Readings Versus Engine Capacity

In the dominant clinical paradigm, obesity, type 2 diabetes, and much of the cardiometabolic spectrum are managed by their most visible dashboard metrics: body weight, fasting glucose, HbA1c, triglycerides, and LDL cholesterol. Interventions that move those numbers—appetite-suppressing drugs, caloric restriction without substrate change, or lipid-lowering agents—are treated as successful when the indicators improve.

The metabolic hypothesis advanced across this series is that those readings are downstream of the actual engine: the mitochondrial networks that determine whether cells can oxidize substrate, maintain redox balance, and respond to load. Obesity, in this framing, is a dashboard expression of chronic engine dysfunction rather than a primary calorie accounting error. Brown adipose tissue offers a particularly clear test case for the hypothesis. It is a specialized, mitochondria-dense tissue whose principal job is not storage but controlled energy dissipation. Its presence and activity in humans track with better metabolic health, which this hypothesis attributes to an increase in the capacity of the engine rather than merely resetting a dashboard light.

What the Large Phenotyping Study Shows

A 2026 Nature study reported 18F-FDG PET–CT findings from 101,243 patients at a major cancer center. Roughly 9 percent had detectable brown adipose tissue. After propensity-score matching for age, sex, BMI, and ambient temperature, the brown-fat-positive group showed lower odds of type 2 diabetes, chronic ischemic heart disease, hypertension, depression, and anxiety. They also exhibited lower glucose and HbA1c, lower triglycerides, higher HDL cholesterol, lower remnant cholesterol, and more favorable echocardiographic indices. Higher quantified brown-fat activity, particularly in the axillary depot, strengthened several of these associations.

The authors noted a finding they described as paradoxical: the brown-fat-positive group had higher total and LDL cholesterol. Under the Lipid Energy Model, a disputed hypothesis, this may not be a paradox. Brown fat is extraordinarily active in lipid trafficking and turnover. In this model, increased consumption of triglyceride-rich lipoproteins is proposed to raise circulating LDL cholesterol while simultaneously improving the remainder of the lipid triad (higher HDL, lower triglycerides, lower remnant cholesterol). In that context, the higher LDL may reflect active fat metabolism rather than metabolic dysfunction. The pattern is consistent with the broader claim in these essays that lipid markers must be interpreted in light of the engine’s substrate handling, not as isolated causal agents.

The study also identified an association between angiotensin-receptor blocker use and higher odds of detectable brown fat. Mechanistic follow-up showed that losartan and one of its metabolites activate PPARγ and upregulate UCP1 in cultured cells, and that losartan increases whole-body energy expenditure in mice. This is of interest as a potential repurposing signal, but it remains secondary to the physiologic levers that already recruit the tissue.

Energy Flux, Pathways, and Mitochondrial Uncoupling

Brown adipocytes contain dense mitochondrial networks whose inner membranes express uncoupling protein 1 (UCP1). When activated, UCP1 opens a proton conduit that allows protons to re-enter the matrix without driving ATP synthase. The free energy of the electrochemical gradient is dissipated as heat rather than captured chemically. This controlled uncoupling converts the tissue into a high-capacity furnace for substrate oxidation.

The principal activating pathway is sympathetic. Cold exposure is sensed by cutaneous thermoreceptors and relayed through the hypothalamus, which increases sympathetic outflow. Norepinephrine released at brown-adipocyte nerve terminals binds β-adrenergic receptors (β3 in rodents; a different subtype appears to dominate in humans), elevating cAMP, activating protein kinase A, and stimulating hormone-sensitive lipase and adipose triglyceride lipase. The resulting free fatty acids both serve as fuel and activate UCP1. Concurrently, glucose uptake rises via GLUT1 and GLUT4 translocation, and circulating triglyceride-rich lipoproteins are cleared by lipoprotein lipase. The net result is simultaneous clearance of glucose and lipid from the blood and their conversion into heat.

Sustained recruitment depends on mitochondrial biogenesis and the browning of white adipose tissue. PGC-1α, co-activated by AMPK, SIRT1, and β-adrenergic signaling, drives expression of UCP1, respiratory-chain subunits, and mitochondrial transcription factors. In animal studies, FGF21, irisin (FNDC5), and other myokines and hepatokines further support the thermogenic program. Ketone bodies, particularly β-hydroxybutyrate, act both as alternative fuel and as signaling molecules that upregulate mitochondrial proteins and thermogenic genes in adipose tissue in cell and animal studies. The overall energy flux therefore rises: substrate is imported, oxidized, and dissipated without obligatory ATP production, increasing whole-body energy expenditure while improving circulating metabolic markers.

This flux is not continuous. It is gated by sympathetic tone, substrate availability, circadian phase, and thermal load. In individuals with active brown fat, cold challenge may raise energy expenditure, and the rise tracks brown-fat activity. The same tissue also secretes batokines that, mainly in rodent studies, influence hepatic glucose production, vascular function, and systemic inflammation. The clinical associations observed in the large phenotyping study would, in this hypothesis, be the expected systemic readout of elevated, controlled energy flux through a specialized mitochondrial compartment.

A Testable Hypothesis: Nocturnal Mitochondrial Quality Control and Cardiac Load Buffering

The engine-capacity framing suggests a further, temporally specific role for brown fat that has not been directly tested. During deep non-REM sleep the major active-phase consumers of metabolic load are downregulated: skeletal muscle activity and tone are reduced, cerebral activity declines in multiple regions, heart rate and blood pressure fall (nocturnal dipping), and core body temperature drops. These coordinated reductions may lower aggregate ATP demand and may create a privileged window for restoration of adenine nucleotide charge and for mitochondrial quality-control processes, including mitophagy. Late eating may disrupt this window by raising nocturnal glucose and shifting fuel use, and it has been linked to poorer sleep quality in observational data, though a controlled trial found no change in sleep architecture.

The heart, however, cannot fully downregulate. It must continue to beat. Residual thermoregulatory demand also persists as core temperature declines. Brown adipose tissue—particularly the mediastinal and pericardial depots that express UCP1 and beige markers and lie in direct anatomic and vascular proximity to the myocardium—is proposed here to be positioned to absorb part of that residual thermal and substrate load. By performing uncoupled respiration, these depots could limit the fraction of cardiac mitochondrial capacity that must be diverted to heat production, keep circulating glucose and fatty acids lower, and thereby could help maintain a higher adenine nucleotide charge in the cardiomyocyte during the hours when mitophagy and other quality-control processes are favored.

This is offered as an explicit, testable hypothesis: detectable and active brown fat, especially in pericardial and mediastinal locations, functions in part as a nocturnal mitochondrial buffer that preserves adenine charge and quality-control capacity in continuously obligatory tissues (most notably the heart) and in the system as a whole. The epidemiologic associations between brown fat and better metabolic markers, lower cardiovascular disease odds, and more favorable echocardiographic indices would then partly reflect the cumulative effect of this buffering across years, rather than solely acute daytime energy expenditure. Supporting observations already exist—circadian control of brown-fat activity, the presence of thermogenic markers in epicardial fat, and a proposed link between sleep and mitochondrial recovery—but direct measurements of nocturnal brown-fat contribution to cardiac mitochondrial quality control do not. The hypothesis predicts that cooler sleeping temperatures, preserved nocturnal dipping, and higher pericardial or mediastinal brown-fat activity will correlate with better markers of cardiac recovery and systemic mitochondrial quality control, and that disruption of the nocturnal window (late eating, elevated ambient temperature, loss of dipping) will attenuate those associations.

Ancestral Selection for Flexible Energy Flux and Circadian Entrainment Memory

The capacity for rapid, reversible increases in energy flux through brown and beige adipose tissue is proposed to have been shaped by ancestral environments that imposed intermittent thermal stress, variable fuel availability, and strong circadian and seasonal cues. Human populations likely lived for much of their evolutionary history under conditions of cooler ambient temperatures at night and in winter, periodic food scarcity that produced natural ketosis and fasting, and daily light–dark cycles that entrained both behavior and physiology.

Cold selection pressure may have favored individuals who could defend core temperature without continuous shivering by recruiting non-shivering thermogenesis. The same environments may also have selected for the ability to switch rapidly between lipid storage and lipid oxidation. When food was abundant and temperatures mild, white adipose tissue stored surplus energy; when temperatures fell or food became scarce, sympathetic activation and elevated ketones would have shifted adipose tissue toward thermogenic flux. This metabolic flexibility is the biological substrate of the brown-fat phenotype.

Circadian entrainment supplied a temporal memory of those conditions. Core body temperature, sympathetic tone, and brown-fat activity exhibit daily rhythms, with higher thermogenic capacity toward the active phase in individuals who possess the tissue. Light, temperature, and feeding timing all entrain these rhythms. The modern mismatch—constant thermal comfort, continuous high-insulin fueling, and disrupted light exposure—may remove the ancestral signals that maintained the tissue’s mitochondrial density and responsiveness. Detectable brown fat declines with age and is suppressed by warm, thermoneutral conditions; a role for high-carbohydrate environments is proposed here. In this hypothesis, the tissue’s residual capacity is a form of circadian and seasonal entrainment memory: a latent engine reserve that reappears when the ancestral signals of cold, ketosis, and appropriate timing are restored. The nocturnal buffering role hypothesized above is a natural extension of that memory: the same tissue that defends temperature under ancestral cold would also protect adenine charge and quality control in the continuously beating heart once other loads have been downregulated.

EnSurf Pillars as Coordinated Recruitment of This Tissue

The three EnSurf pillars—Fuel, Circadian, and Strength—already contain the principal physiologic signals that both activate existing brown fat and promote its recruitment or the browning of white adipose tissue. These are not dashboard overrides. They are substrate, thermal, and contractile stimuli that remodel mitochondrial networks in adipose tissue.

Fuel

Ketogenic diets and elevated β-hydroxybutyrate increase brown-fat mitochondrial size, oxidative-phosphorylation proteins, and UCP1 content in animal models. In cell and animal studies, the same conditions can promote browning of white adipose tissue through AMPK–SIRT1–PGC-1α signaling, FGF21, and related pathways. In mice, fasting regimens can remodel adipose tissue and enhance thermogenic gene programs; a ketone-driven route is proposed here. In the engine framing, this is the use of stored fat as the preferred fuel under low-insulin, high-fat-oxidation conditions—the ancestral default rather than a continuous high-carbohydrate load that favors storage and de novo lipogenesis.

Circadian and Thermal

Cold exposure is the primary physiologic activator of brown fat. Sympathetic norepinephrine acting on β-adrenergic receptors (β3 in rodents) rapidly stimulates UCP1-dependent thermogenesis; repeated mild cold increases brown-fat activity in humans and recruits beige adipocytes in mice. Human data show that cooler overnight temperatures increase detectable brown-fat activity, and that repeated cold exposure increases brown-fat activity and energy expenditure. Brown-fat thermogenesis itself exhibits circadian variation. Thermal hormesis and circadian entrainment are already elements of the Circadian pillar; the brown-fat literature simply makes the adipose-specific metabolic return more explicit. Cooler nocturnal environments would be expected to engage the hypothesized nocturnal buffering function directly.

Strength and Hormesis

In rodents, exercise contributes to white-fat browning, with irisin/FNDC5, FGF21, and local metabolic signals proposed as routes; resistance exercise raises circulating irisin in humans, but whether this browns human fat is unsettled. More broadly, hormetic stressors improve mitochondrial biogenesis and quality control. Cold is itself a potent adipose-specific hormetic signal. Supporting mitochondrial biogenesis and function—the central aim of the Strength pillar and of mitochondrial-support interventions—may help supply the dense mitochondrial networks that define brown fat. The combination of mechanical load and thermal challenge would therefore reinforce the same tissue phenotype.

Collectively the pillars act at multiple nodes: they supply ketone and fatty-acid substrate, impose the thermal and sympathetic signals that activate UCP1, and support the mitochondrial biogenesis required for sustained thermogenic capacity. The proposed result is an increase in the engine’s ability to dissipate energy as heat rather than a forced reduction in intake. They also preserve the temporal and thermal conditions under which the hypothesized nocturnal quality-control buffering can operate.

Relation to the Obesity and Atherosclerosis Hypotheses

The obesity essay in this series argued that medically supervised prolonged fasting integrated with metabolic optimization more effectively restores engine function than chronic GLP-1 agonism, because the former drives proteomic and mitochondrial recalibration while the latter primarily overrides appetite signals. Brown-fat activation is a concrete example of the same distinction. Increased brown-fat activity may raise energy expenditure under cold challenge in individuals who possess the tissue, may improve glucose and lipid clearance, and is associated with healthier fat distribution. These are engine-level changes. They do not require perpetual receptor occupancy.

The higher-LDL finding in the brown-fat-positive group is conceptually continuous with the metabolic-atherosclerosis hypothesis, a disputed reading: when mitochondria can properly traffic and oxidize lipid, circulating LDL may rise as a consequence of increased turnover without the accompanying high triglycerides, low HDL, and inflammatory signature that mark dysfunctional fuel partitioning. Context may determine whether the marker reflects engine activity or engine failure.

The Hypothesis

The central hypothesis is that detectable and active brown adipose tissue is a specialized expression of mitochondrial capacity for controlled uncoupling and lipid trafficking. Its epidemiologic associations with lower odds of diabetes, cardiovascular disease, and certain psychiatric conditions reflect improved engine function rather than an independent protective factor. A further, testable extension is that brown fat—particularly pericardial and mediastinal depots—functions in part as a nocturnal mitochondrial buffer that absorbs residual thermal and substrate load once other high-demand tissues have downregulated, thereby preserving adenine nucleotide charge and quality-control capacity in the continuously beating heart and in the system as a whole.

The same Fuel (ketone-supported fasting and fat oxidation), Circadian (cold and thermal entrainment, including cooler nocturnal environments), and Strength (contractile and hormetic stimuli that support mitochondrial biogenesis) interventions already emphasized in the EnSurf framework are proposed to be sufficient to recruit and activate this tissue in suitable individuals. These interventions operate by ordinary substrate, sympathetic, and stress-response physiology. They would increase the engine’s capacity to clear and oxidize fuel as heat, producing more lasting shifts in metabolic state rather than temporary dashboard adjustments that leave the underlying mitochondrial networks unrepaired. They also maintain the conditions under which the hypothesized nocturnal buffering can occur.

The observational nature of the large PET cohort, the incomplete translation of every animal finding, the real individual variation in cold tolerance, ketosis, and fasting response, and the absence of direct measurements of nocturnal brown-fat contribution to cardiac mitochondrial quality control remain important limits. The mechanistic alignment with the engine-repair thesis, however, is direct: brown fat is mitochondria doing what mitochondria do when properly signaled—moving substrate and dissipating energy under ancestral conditions of temperature variation, intermittent fuel availability, and physical load, including during the nocturnal window when other loads are reduced.

Conclusion: Restoring Ancestral Energy Flux

Brown adipose tissue illustrates the central claim of this metabolic hypothesis series with unusual clarity. It is not a storage depot whose size is to be minimized by appetite suppression or caloric accounting. It is a mitochondria-rich engine compartment whose capacity for controlled energy flux—import of glucose and lipid, oxidation through uncoupled respiration, and dissipation as heat—correlates with better systemic metabolic health. The higher LDL observed in brown-fat-positive individuals may be consistent with active lipid trafficking rather than pathology, a disputed reading that would reinforce the principle that markers must be read in the context of engine function.

A further, testable implication is that this same capacity serves a nocturnal quality-control function. Once skeletal muscle and much of the brain have reduced their load, residual thermoregulatory demand persists as core temperature falls. Brown fat, especially the depots adjacent to the heart, could meet part of that demand and thereby help preserve adenine charge and mitophagy capacity in the one major organ that cannot fully rest. The epidemiologic associations with better metabolic and cardiac markers would then partly reflect the cumulative effect of this buffering across years.

This capacity is proposed to have been selected under ancestral conditions that combined intermittent cold, periodic ketosis and fasting, physical activity, and strong circadian light and temperature cycles. Modern thermoneutral, high-insulin environments may erase the signals that maintain it, converting a latent, flexible flux system into a largely silent tissue. The EnSurf pillars are proposed to restore those signals: Fuel supplies the ketones and fatty acids that remodel adipose mitochondria; Circadian and thermal practices reintroduce the cold and entrainment cues—including cooler nocturnal environments—that activate UCP1 and recruit beige adipocytes; Strength and hormesis support the biogenesis and quality of the mitochondrial networks required for sustained thermogenesis.

The practical implication is frugal and engine-centered. Rather than perpetually overriding dashboard signals with pharmacologic appetite suppression, the same ancestral inputs that selected for brown-fat capacity can be reapplied under medical supervision where appropriate. The hypothesized result is not a temporary reduction in energy intake but an increase in the engine’s ability to move and dissipate substrate—both during the day and during the nocturnal window when quality control is prioritized. In that restoration of flexible energy flux lies the durable metabolic advantage hypothesized throughout this series.

Reference: Gómez-Banoy N, … Cohen P. Artificial intelligence-enabled clinical phenotyping of human brown fat. Nature, 14 October 2026. doi:10.1038/s41586-026-11162-7

Coach version: Coach — Brown Fat.

A working hypothesis, open to correction and revised as new evidence arrives. Last revised October 31, 2026.

References

1. Cannon B, Nedergaard J, 2004. Brown adipose tissue: function and physiological significance. Physiological Reviews 84(1):277-359. doi:10.1152/physrev.00015.2003
2. Gómez-Banoy N, Barrero JA, Pinheiro de Carvalho LR, et al., 2026. Artificial intelligence-enabled clinical phenotyping of human brown fat. Nature (published online 2026-10-14; volume and pages not yet assigned). doi:10.1038/s41586-026-11162-7
3. Becher T, Palanisamy S, Kramer DJ, et al., 2021. Brown adipose tissue is associated with cardiometabolic health. Nature Medicine 27(1):58-65. doi:10.1038/s41591-020-1126-7
4. Norwitz NG, Soto-Mota A, Kaplan B, et al., 2022. The Lipid Energy Model: Reimagining Lipoprotein Function in the Context of Carbohydrate-Restricted Diets. Metabolites 12(5):460. doi:10.3390/metabo12050460
5. Bartelt A, Bruns OT, Reimer R, et al., 2011. Brown adipose tissue activity controls triglyceride clearance. Nature Medicine 17(2):200-205. doi:10.1038/nm.2297
6. Ouellet V, Labbé SM, Blondin DP, et al., 2012. Brown adipose tissue oxidative metabolism contributes to energy expenditure during acute cold exposure in humans. Journal of Clinical Investigation 122(2):545-552. doi:10.1172/JCI60433
7. Berbée JF, Boon MR, Khedoe PP, et al., 2015. Brown fat activation reduces hypercholesterolaemia and protects from atherosclerosis development. Nature Communications 6:6356. doi:10.1038/ncomms7356
8. Fedorenko A, Lishko PV, Kirichok Y, 2012. Mechanism of fatty-acid-dependent UCP1 uncoupling in brown fat mitochondria. Cell 151(2):400-413. doi:10.1016/j.cell.2012.09.010
9. Blondin DP, Nielsen S, Kuipers EN, et al., 2020. Human Brown Adipocyte Thermogenesis Is Driven by β2-AR Stimulation. Cell Metabolism 32(2):287-300.e7. doi:10.1016/j.cmet.2020.07.005
10. Puigserver P, Wu Z, Park CW, et al., 1998. A cold-inducible coactivator of nuclear receptors linked to adaptive thermogenesis. Cell 92(6):829-839. doi:10.1016/s0092-8674(00)81410-5
11. Qiang L, Wang L, Kon N, et al., 2012. Brown remodeling of white adipose tissue by SirT1-dependent deacetylation of Pparγ. Cell 150(3):620-632. doi:10.1016/j.cell.2012.06.027
12. Fisher FM, Kleiner S, Douris N, et al., 2012. FGF21 regulates PGC-1α and browning of white adipose tissues in adaptive thermogenesis. Genes & Development 26(3):271-281. doi:10.1101/gad.177857.111
13. Boström P, Wu J, Jedrychowski MP, et al., 2012. A PGC1-α-dependent myokine that drives brown-fat-like development of white fat and thermogenesis. Nature 481(7382):463-468. doi:10.1038/nature10777
14. Carrière A, Jeanson Y, Berger-Müller S, et al., 2014. Browning of white adipose cells by intermediate metabolites: an adaptive mechanism to alleviate redox pressure. Diabetes 63(10):3253-3265. doi:10.2337/db13-1885
15. Srivastava S, Kashiwaya Y, King MT, et al., 2012. Mitochondrial biogenesis and increased uncoupling protein 1 in brown adipose tissue of mice fed a ketone ester diet. The FASEB Journal 26(6):2351-2362. doi:10.1096/fj.11-200410
16. Yoneshiro T, Aita S, Matsushita M, et al., 2013. Recruited brown adipose tissue as an antiobesity agent in humans. Journal of Clinical Investigation 123(8):3404-3408. doi:10.1172/JCI67803
17. Lee P, Bova R, Schofield L, et al., 2016. Brown Adipose Tissue Exhibits a Glucose-Responsive Thermogenic Biorhythm in Humans. Cell Metabolism 23(4):602-609. doi:10.1016/j.cmet.2016.02.007
18. Villarroya F, Cereijo R, Villarroya J, et al., 2017. Brown adipose tissue as a secretory organ. Nature Reviews Endocrinology 13(1):26-35. doi:10.1038/nrendo.2016.136
19. Maquet P, Degueldre C, Delfiore G, et al., 1997. Functional neuroanatomy of human slow wave sleep. The Journal of Neuroscience 17(8):2807-2812. doi:10.1523/JNEUROSCI.17-08-02807.1997
20. Kräuchi K, 2007. The thermophysiological cascade leading to sleep initiation in relation to phase of entrainment. Sleep Medicine Reviews 11(6):439-451. doi:10.1016/j.smrv.2007.07.001
21. Gu C, Brereton N, Schweitzer A, et al., 2020. Metabolic Effects of Late Dinner in Healthy Volunteers-A Randomized Crossover Clinical Trial. The Journal of Clinical Endocrinology & Metabolism 105(8):2789-2802. doi:10.1210/clinem/dgaa354
22. Crispim CA, Zimberg IZ, dos Reis BG, et al., 2011. Relationship between food intake and sleep pattern in healthy individuals. Journal of Clinical Sleep Medicine 7(6):659-664. doi:10.5664/jcsm.1476
23. Sacks HS, Fain JN, Holman B, et al., 2009. Uncoupling protein-1 and related messenger ribonucleic acids in human epicardial and other adipose tissues: epicardial fat functioning as brown fat. The Journal of Clinical Endocrinology & Metabolism 94(9):3611-3615. doi:10.1210/jc.2009-0571
24. Sacks HS, Fain JN, Bahouth SW, et al., 2013. Adult epicardial fat exhibits beige features. The Journal of Clinical Endocrinology & Metabolism 98(9):E1448-E1455. doi:10.1210/jc.2013-1265
25. Matsushita M, Nirengi S, Hibi M, et al., 2021. Diurnal variations of brown fat thermogenesis and fat oxidation in humans. International Journal of Obesity 45(11):2499-2505. doi:10.1038/s41366-021-00927-x
26. Sazzini M, Schiavo G, De Fanti S, et al., 2014. Searching for signatures of cold adaptations in modern and archaic humans: hints from the brown adipose tissue genes. Heredity 113(3):259-267. doi:10.1038/hdy.2014.24
27. Au-Yong IT, Thorn N, Ganatra R, et al., 2009. Brown adipose tissue and seasonal variation in humans. Diabetes 58(11):2583-2587. doi:10.2337/db09-0833
28. Lee P, Smith S, Linderman J, et al., 2014. Temperature-acclimated brown adipose tissue modulates insulin sensitivity in humans. Diabetes 63(11):3686-3698. doi:10.2337/db14-0513
29. Cypess AM, Lehman S, Williams G, et al., 2009. Identification and importance of brown adipose tissue in adult humans. New England Journal of Medicine 360(15):1509-1517. doi:10.1056/NEJMoa0810780
30. Yoneshiro T, Aita S, Matsushita M, et al., 2011. Age-related decrease in cold-activated brown adipose tissue and accumulation of body fat in healthy humans. Obesity 19(9):1755-1760. doi:10.1038/oby.2011.125
31. van der Lans AA, Hoeks J, Brans B, et al., 2013. Cold acclimation recruits human brown fat and increases nonshivering thermogenesis. Journal of Clinical Investigation 123(8):3395-3403. doi:10.1172/JCI68993
32. Srivastava S, Baxa U, Niu G, et al., 2013. A ketogenic diet increases brown adipose tissue mitochondrial proteins and UCP1 levels in mice. IUBMB Life 65(1):58-66. doi:10.1002/iub.1102
33. Li G, Xie C, Lu S, et al., 2017. Intermittent Fasting Promotes White Adipose Browning and Decreases Obesity by Shaping the Gut Microbiota. Cell Metabolism 26(4):672-685.e4. doi:10.1016/j.cmet.2017.08.019
34. Wu J, Boström P, Sparks LM, et al., 2012. Beige adipocytes are a distinct type of thermogenic fat cell in mouse and human. Cell 150(2):366-376. doi:10.1016/j.cell.2012.05.016
35. Stanford KI, Middelbeek RJ, Goodyear LJ, 2015. Exercise Effects on White Adipose Tissue: Beiging and Metabolic Adaptations. Diabetes 64(7):2361-2368. doi:10.2337/db15-0227
36. Tsuchiya Y, Ando D, Takamatsu K, et al., 2015. Resistance exercise induces a greater irisin response than endurance exercise. Metabolism 64(9):1042-1050. doi:10.1016/j.metabol.2015.05.010
37. Timmons JA, Baar K, Davidsen PK, et al., 2012. Is irisin a human exercise gene?. Nature 488(7413):E9-E10. doi:10.1038/nature11364
38. Ristow M, Schmeisser K, 2014. Mitohormesis: Promoting Health and Lifespan by Increased Levels of Reactive Oxygen Species (ROS). Dose-Response 12(2):288-341. doi:10.2203/dose-response.13-035.Ristow

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