There is a group of overweight/obesity that is characterized by having a lower risk of cardiomethabolic complications, also the so -called overweight phenotype or metabolically healthy obesity. 1–4 This group has similar levels of adiposity that those with overweight/metabolically unhealthy obesity, but without presenting dyslipidemia, hyperglycemia or hypertension. 1,2 However, it should be noted that people underwear or metabolically healthy obesity have the potential risk to progress towards the non -healthy phenotype. 1.2
In this way, although people with metabolically healthy overweight or obesity have a total adiposity similar to those with the non -healthy phenotype, the distribution of fat is quite different between both groups. Those overweight or metabolically healthy obese have higher levels of subcutaneous adipose tissue and lower visceral adipose tissue compared to people with overweight/metabolically not healthy obesity. 5–7 However, the differences in brown adipose tissue have not been previously studied.
What is brown adipose tissue?
The brown adipose tissue, also known as brown adipose tissue, is a type of fat that can dissipate energy in the form of heat through the consumption of different energy substrates, thanks mainly to the decoupling protein (UCP1). 8 This increase in energy expenditure to dissipate energy is clearly observed in response to cold exposure (main stimulus) or a meal. In addition, brown adipose tissue helps regulate body temperature after heat dissipation in the form of heat in response to the mentioned stimuli. Finally, in addition to this energy and thermoregulatory role, the brown adipose tissue has a key endocrine function since it is capable of producing and freeing the bloodstream different molecules, also known as Batokines , with key functions in metabolism due to its performance in performance in different organs and tissues. 9
In this sense, a previous study that included more than 130,000 participants showed that those patients with obesity and detectable brown adipose tissue presented a lower prevalence of dyslipidemia (-7.9%), hypertension (-7.9%), coronary heart disease (-3%) , and congestive heart failure (-1.6%) that those with obesity and without detectable brown adipose tissue. 10 Therefore, it would be expected that people with metabolically healthy obesity have greater volume and activity of brown adipose tissue.
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What differences exist in the brown adipose tissue between people with metabolically healthy obesity and those with non -healthy obesity?
To answer this question, researchers from the Research Group of the Sports and Health University Institute (IMUDS) of the University of Granada led by Dr. Jonatan Ruiz carried out a study in which they compared the volume and activity of the Brown Adipose Fabric, the temperature, and the energy expenditure both at rest and in response to a cold exposure and after a meal between a group of overweight/obesity and a healthy metabolic profile and another group with A non -healthy metabolic profile.11
The results of the study published in the prestigious Ebiomedicine showed that the underwear/metabolically healthy obesity had a greater amount ( +124%) and activity (~ +100%) of the brown adipose tissue compared to the metabolically unhealthy group ( Figure 1 ).
Figure 1. Images of two representative individuals, one metabolically healthy but with obesity and another metabolically not healthy and with obesity. Blue points indicate the volume of brown adipose tissue and red points indicate the maximum brown adipose tissue (maximum standardized absorption value).
In addition, in the study, led by Dr. Lucas Jurado-Fasoli, it was shown that people with a metabolically healthy overweight/obesity had a higher energy expenditure in response to a mixed composition meal in macronutrients and in response to acute exposure to the cold compared to those metabolically unhealthy ( Figure 2 ). These results could once again demonstrate the energy role of brown adipose tissue, this time in overweight/obesity.
Finally, people with overweight/metabolically healthy obesity stable stable the skin temperature in the supraclavicular zone in response to a meal and before acute exposure to cold compared to their metabolically unhealthy homologues. Note that the skin temperature in the supraclavicular zone has been previously used as an indirect method for the evaluation of brown adipose tissue activity ( Figure 2 ), revealing in turn the role of brown adipose tissue in thermoregulation.
Infographic Summary of the scientific article.
Therefore, the results regarding the differences in brown adipose tissue, energy expenditure and skin temperature are online, and demonstrate the potential role of brown adipose tissue in the healthy phenotype.
What implications could these results have?
Together, the results of the research suggest a role of brown adipose tissue when conferring a metabolically healthy phenotype in young adults with overweight or obesity. In addition, our results provide evidence on the potential role of brown adipose tissue in energy expenditure and cardiometabolic health.
These novel results are a first step for future studies to investigate the effect of brown adipose tissue activators (eg, cold exposure, drugs), in the prevention of metabolic alterations and reduction of the risk of cardiomethabolic pathologies in overweight people or obesity.
References:
1. Karelis, Ad Metabolically Healthy But Obese Individuals. The Lancet 372 , 1281–1283 (2008).
2. Primeau, V. et al. Characterizing The Profile of Obese Patients Who Are metabolically Healthy. International Journal of Obesity Vol. 35 971–981 Preprint at https://doi.org/10.1038/ijo.2010.216 (2011).
3. Bell, Ja et al. INCINDENCE OF METABOLIC RISK FACTORS AMONG HEALTHY OBESE ADULTS: 20-YEAR FOLLOW-UP. J AM COLL CARDIOL 66 , 871–873 (2015).
4. Gómez-Ambrosi, J. et al. BODY MASS INDEX CLASSIFICATION MISSES SUBJECTS WITH INCREASED CARDIOMETABOLIC RISK FACTORS RELATED TO ELEVATED ADAPOSITY. INT J OBES 36 , 286–294 (2012).
5. Tchernof, A. & Després, JP Pathophysiology of Humn Visceral Obesity: An Update. Physiol Rev 93 , 359–404 (2013).
6. Carpentier, AC, Blondin, DP, Haman, F. & Richard, D. Brown Adipose Tissue - A Translational Perspective. Endoc Rev 44 , 143–192 (2022).
7. Tanrioover, C. et al. Metabolically Healthy Obesity: Misleading Phrase or Healthy Phenotype? EUR J INTERN MED (2023) DOI: 10.1016/J.EJIM.2023.02.025.
8. Cannon, B. & Nedergaard, J. Brown Adipose Tissue: Function and Physiological Signance. Physiol Rev 84 , 277–359 (2004).
9. Villarroya, F., Cereijo, R., Villarroya, J. & Giralt, M. Brown Adipose Tissue as a secretory organ. Nat Rev Endocrinol 13 , 26–35 (2017).
10. Becher, T. et al. Brown Adipose Tissue is Associated with Cardiometabolic Health. Nat Med 27 , 58–65 (2021).
11. JURADO-FASOLI, L. et al. Adults with Metabolically Healthy Overweight Or Obesity present More Brown Adipose Tissue and Higher ThemoGenesis than their metabolically unhealthy counterparts . www.thelancet.com (2023).
Main authors of the study:
Dr. Jonatan Ruiz Ruiz
Department of Physical and Sports Education, Faculty of Sports Sciences, Mixed Institute University and Health University (IMUDS) of the UGR; Ibs.Granada and Cyberobn
Email: ruizj@ugr.es
Dr. Lucas Jurado Fasoli
Department of Physiology, Faculty of Medicine, Sports and Health University Institute (IMUDS) of the UGR
Email: juradofasoli@ugr.es