Journal of Biomedical Engineering Research (대한의용생체공학회:의공학회지)

The Korean Society of Medical and Biological Engineering (대한의용생체공학회)
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Potential Effects of Micro-Current Stimulation for Reduction of Abdominal Fat and Weight Loss: Clinical Study

미세 전류 자극에 따른 복부 체지방 감소 및 다이어트 효과에 대한 임상 시험 연구

  • Cho, Seungkwan (CELLOGIN Inc.) ;
  • Kim, Seongguk (CELLOGIN Inc.) ;
  • Kim, Donghyun (Department of Biomedical Engineering, College of Health Science, Yonsei University) ;
  • Kim, Seohyun (Department of Biomedical Engineering, College of Health Science, Yonsei University) ;
  • Lee, Hana (Department of Biomedical Engineering, College of Health Science, Yonsei University) ;
  • Hwang, Donghyun (Department of Biomedical Engineering, College of Health Science, Yonsei University) ;
  • Kim, Yong-Min (Department of Oriental Medical and Herbal Cosmetic Sciences, Semyung University) ;
  • Shin, Taemin (Department of Biomedical Engineering, College of Health Science, Yonsei University) ;
  • Kim, Han Sung (Department of Biomedical Engineering, College of Health Science, Yonsei University)
  • Received : 2018.12.04
  • Accepted : 2018.12.19
  • Published : 2018.12.31
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Abstract

Obesity is considered as a primary health problem over the past century in line with life environmental changes. It is mainly associated with increased risk of numerous chronic diseases which may significantly reduce health-related quality of life. Therefore, efforts to reduce weight should be performed. This study suggested a novel approach to reduce body fat by applying external stimulation which is micro-current stimulation (MCS). In this clinical study, we evaluated the potential effects of MCS for reduction of abdominal fat and weight loss. Prior to the clinical test, computational simulation was conducted to find the proper MCS conditions that allow externally applied stimulation to reach the internal fat section from the external skin. Particularly, the clinical study evaluated the unilateral effects of MCS for body fat loss and lipolysis without any additional limitations such as physical exercise and dietary therapy. The results showed that whole body fat, waist circumferences, and abdominal fat are gradually decreased after intervention in proportion to the time. From the results, we can estimate that MCS can be effective on the body fat loss by activation of lipolysis in human adipose.

Keywords

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그림 1. 피부 및 내부 조직에 대한 개념도 Fig. 1. Composite model of skin and inner tissue

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그림 2. 선행 논문에 근거한 지방 조직의 유전 특성 데이터 [53]: (a) 유전율, (b) 전도 도 Fig. 2. Replotted dielectric data in adipose tissue from the literature [53]: (a) permittivity, (b) conductivity

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그림 3. 임상 시험에서 활용한 시스템 (좌: 인바디, 우: 덱사) Fig. 3. Data acquisition system for clinical test (left: INBODY, right: DXA)

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그림 4. 10Hz의 주파수에서 전류 크기를 변화하였을 때의 전기 변위 장: (a) 선형, (b) 대수 스케일 Fig. 4. Electric displacement fields of varying intensities with 10Hz at final time step: (a) linear, (b) logarithmic scale of y axis

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그림 5. 100Hz의 주파수에서 전류 크기를 변화하였을 때의 전기 변위 장: (a) 선형, (b) 대수 스케일 Fig. 5. Electric displacement fields of varying intensities with 100 Hz at final time step: (a) linear, (b) logarithmic scale of y axis

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그림 6. 지방 층의 동일 지점에서 주파수 변화에 따른 전기 변위장 비교: (a) 100 ㎂, (b) 400㎂ (t = 3) Fig. 6. Comparative results of electric displacement field between under 10Hz and 100Hz at the same position: (a) 100 ㎂, (b) 400 ㎂ (t = 3)

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그림 7. 인바디 측정 결과: (a): 전신 체지방, (b) 허리둘레, (c) 감소율 Fig. 7. Results measured by INBODY: (a): whole body fat, (b) waist circumference and (c) reduction rate. The data are represented by mean with SD (*: p < 0.05, ** p < 0.005)

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그림 8. 덱사 측정 결과: (a): 전신 체지방, (b) 몸통(복부) 지방, (c) 감소율 Fig. 8. Results measured by DXA: (a): whole body fat, (b) trunk(abdominal) fat and (c) reduction rate. The data are represented by mean with SD (*: p < 0.05)

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그림 9. 생체전류 피드백 회로에 대한 개념도 Fig. 9. Conceptual flow chart of bio-current feedback system

표 1. 모델링 정보 및 전기 물성치 (주파수 특성 반영) Table 1. Information of computational modeling and electric properties under different frequencies

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표 2. 피험자 키와 몸무게 정보 Table 2. Height and weight of subjects

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References

  1. S.B. Heymsfield and T.A. Wadden, "Mechanisms, pathophysiology, and management of obesity", N. Engl. J. Med., vol.376, no. 3, pp.254-266, 2017. https://doi.org/10.1056/NEJMra1514009
  2. P. Poirier, Adiposity and cardiovascular disease: are we using the right definition of obesity? 2007, Oxford University Press.
  3. K.M. Gadde, C.K. Martin, H.-R. Berthoud and S.B. Heymsfield, "Obesity: Pathophysiology and management", J. Am. Coll. Car., vol.71, no. 1, pp.69-84, 2018. https://doi.org/10.1016/j.jacc.2017.11.011
  4. G.O. Collaborators, "Health effects of overweight and obesity in 195 countries over 25 years", N. Engl. J. Med., vol.377, no. 1, pp.13-27, 2017. https://doi.org/10.1056/NEJMoa1614362
  5. J. Fanning, M.P. Walkup, W.T. Ambrosius, L.R. Brawley, E.H. Ip, A.P. Marsh and W.J. Rejeski, "Change in health-related quality of life and social cognitive outcomes in obese, older adults in a randomized controlled weight loss trial: Does physical activity behavior matter?", J. Beh. Med., vol.41, no. 3, pp.299-308, 2018. https://doi.org/10.1007/s10865-017-9903-6
  6. I. Imayama, C.M. Alfano, A. Kong, K.E. Foster-Schubert, C.E. Bain, L. Xiao, C. Duggan, C.-Y. Wang, K.L. Campbell and G.L. Blackburn, "Dietary weight loss and exercise interventions effects on quality of life in overweight/obese postmenopausal women: a randomized controlled trial", Int. J. Beh. Nutr. Phy. Act, vol.8, no. 1, pp.118, 2011. https://doi.org/10.1186/1479-5868-8-118
  7. B. Blissmer, D. Riebe, G. Dye, L. Ruggiero, G. Greene and M. Caldwell, "Health-related quality of life following a clinical weight loss intervention among overweight and obese adults: intervention and 24 month follow-up effects", Heal. Qual. L. O., vol.4, no. 1, pp.43, 2006. https://doi.org/10.1186/1477-7525-4-43
  8. K. Fontaine and I. Barofsky, "Obesity and health?related quality of life", O. Rev., vol.2, no. 3, pp.173-182, 2001. https://doi.org/10.1046/j.1467-789x.2001.00032.x
  9. R.C. Gaspar, V.R. Munoz, G.P. Formigari, G.K. Kuga, S.C.B.R. Nakandakari, J.D. Botezelli, A.S. da Silva, D.E. Cintra, L.P. de Moura and E.R. Ropelle, "Acute physical exercise increases the adaptor protein APPL1 in the hypothalamus of obese mice". Cytokine, vol.110, no. pp.87-93, 2018. https://doi.org/10.1016/j.cyto.2018.04.013
  10. V.R. Munoz, R.C. Gaspar, B.M. Crisol, G.P. Formigari, M.R. Sant'Ana, J.D. Botezelli, R.S. Gaspar, A.S. da Silva, D.E. Cintra and L.P. de Moura, "Physical exercise reduces pyruvate carboxylase (PCB) and contributes to hyperglycemia reduction in obese mice", J. Phy. Sci., vol.68, no. 4, pp.493-501, 2018. https://doi.org/10.1007/s12576-017-0559-3
  11. N. Zhang and S. Bi, "Effects of physical exercise on food intake and body weight: Role of dorsomedial hypothalamic signaling", Phy. & Beh., no. 2018.
  12. S. Aboueid, C. Pouliot, I. Bourgeault and I. Giroux, "A Systematic Review of Interprofessional Collaboration for Obesity Management in Primary Care, A Focus on Dietetic Referrals", J. Res. Int. Pra. and Edu., vol.8, no. 1, 2018.
  13. S. Aboueid, C. Pouliot, I. Bourgeault and I. Giroux, "Dietetic Referral Practices for Obesity Management in Primary Healthcare: A Systematic Review", J. Res. Int. Pra. and Edu., vol.8, no. 1, 2018.
  14. V.A. Shrewsbury, T. Burrows, M. Ho, M. Jensen, S.P. Garnett, L. Stewart, M.L. Gow, L.J. Ells, L.K. Chai and L. Ashton, "Update of the best practice dietetic management of overweight and obese children and adolescents: a systematic review protocol", JBI Dat. Sys. Rev. Imp. Rep., vol.16, no. 7, pp.1495-1502, 2018. https://doi.org/10.11124/JBISRIR-2017-003603
  15. H. Buchwald and D.M. Oien, "Metabolic/bariatric surgery worldwide 2008", Obe. Sur., vol.19, no. 12, pp.1605, 2009. https://doi.org/10.1007/s11695-009-0014-5
  16. H. Buchwald and D.M. Oien, "Metabolic/bariatric surgery worldwide 2011", Obe. Sur., vol.23, no. 4, pp.427-436, 2013. https://doi.org/10.1007/s11695-012-0864-0
  17. V.S. Hubbard and W.H. Hall, "Gastrointestinal Surgery for Severe Obesity", Obe. Sur., vol.1, no. 3, pp.257-265, 1991. https://doi.org/10.1381/096089291765560962
  18. R.F. Kushner, "Weight Loss Strategies for Treatment of Obesity: Lifestyle Management and Pharmacotherapy", Pro. Car. Dis., no. 2018.
  19. G. Srivastava and C.M. Apovian, "Current pharmacotherapy for obesity", Nat. Rev. End., vol.14, no. 1, pp.12, 2018. https://doi.org/10.1038/nrendo.2017.122
  20. A. Velazquez and C.M. Apovian, "Updates on obesity pharmacotherapy", Ann. N.Y. Aca. Sci., vol.1411, no. 1, pp.106-119, 2018. https://doi.org/10.1111/nyas.13542
  21. J. Ling, M. Stommel and S.H. Choi, "Attempts to Lose Weight Among US Children: Importance of Weight Perceptions from Self, Parents, and Health Professionals", Obe., vol.26, no. 3, pp.597-605, 2018.
  22. M. Hulens, G. Vansant, R. Lysens, A. Claessens and E. Muls, "Exercise capacity in lean versus obese women", Scan. J. Med. Sci. S., vol.11, no. 5, pp.305-309, 2001. https://doi.org/10.1034/j.1600-0838.2001.110509.x
  23. L.P. Carvalho, L. Di Thommazo-Luporini, R.G. Mendes, R. Cabiddu, P.A. Ricci, R.P. Basso-Vanelli, M.C. Oliveira-Junior, R.P. Vieira, J.C. Bonjorno-Junior and C.R. Oliveira, "Metabolic syndrome impact on cardiac autonomic modulation and exercise capacity in obese adults", A. Neu., vol.213, no. pp.43-50, 2018.
  24. P.A. McAuley, S.J. Keteyian, C.A. Brawner, Z.A. Dardari, M. Al Rifai, J.K. Ehrman, M.H. Al-Mallah, S.P. Whelton and M.J. Blaha. Exercise capacity and the obesity paradox in heart failure: the FIT (Henry Ford Exercise Testing) Project. in Mayo Clinic Proceedings. 2018. Elsevier.
  25. M.M. Rogge and B. Gautam, "Before, after, & after-after: Clinical implications of weight loss recidivism", N. Pra., vol.42, no. 3, pp.18-24, 2017.
  26. R.D. Hensley, "Primary care management of obesity: Individualized treatment strategies", N. Pra., vol.43, no. 7, pp.41-48, 2018. https://doi.org/10.1097/01.NPR.0000534941.27466.0b
  27. R. Pavlovic, D. Trkulja-Petkovic and S. Dragutinovic, "Electro-muscle stimulation-the application in practice", A. Kin. Int. Sci. J. Kin., 10 Suppl, vol.1, no. pp.49-55, 2016.
  28. K.-M. KiM, T. Croy, J. Hertel and S. Saliba, "Effects of neuromuscular electrical stimulation after anterior cruciate ligament reconstruction on quadriceps strength, function, and patient-oriented outcomes: a systematic review", J. Orth. Spo. Phy. The., vol.40, no. 7, pp.383-391, 2010. https://doi.org/10.2519/jospt.2010.3184
  29. J.P. Porcari, K.P. Mclean, C. Foster, T. Kernozek, B. Crenshaw and C. Swenson, "Effects of electrical muscle stimulation on body composition, muscle strength, and physical appearance", J. Str. Con. Res, vol.16, no. 2, pp.165-172, 2002. https://doi.org/10.1519/1533-4287(2002)016<0165:EOEMSO>2.0.CO;2
  30. D. Moreau, P. Dubots, V. Boggio, J.C. Guilland and G. Cometti, "Effects of electromyostimulation and strength training on muscle soreness, muscle damage and sympathetic activation", J. Spo. Sci., vol.13, no. 2, pp.95-100, 1995. https://doi.org/10.1080/02640419508732216
  31. M. Vromans and P.D. Faghri, "Functional electrical stimulation-induced muscular fatigue: Effect of fiber composition and stimulation frequency on rate of fatigue development", J. Electro. Kine., vol.38, no. pp.67-72, 2018. https://doi.org/10.1016/j.jelekin.2017.11.006
  32. T. Kawaguchi, N. Shiba, T. Maeda, T. Matsugaki, Y. Takano, M. Itou, M. Sakata, E. Taniguchi, K. Nagata and M. Sata, "Hybrid training of voluntary and electrical muscle contractions reduces steatosis, insulin resistance, and IL-6 levels in patients with NAFLD: a pilot study", J. Gast., vol.46, no. 6, pp.746-757, 2011. https://doi.org/10.1007/s00535-011-0378-x
  33. C.M. Gregory and C.S. Bickel, "Recruitment patterns in human skeletal muscle during electrical stimulation", Phy. Ther., vol.85, no. 4, pp.358-364, 2005.
  34. K.F. Migliato, M.A. Chiosini, F.A. Mendonca, M.A. Esquisatto, H.R. Salgado and G.M. Santos, "Effect of Glycolic Extract of Dillenia indica L. Combined with microcurrent stimulation on experimental lesions in wistar rats", Wounds, vol.23, no. 5, pp.111, 2011.
  35. N. Cheng, H. Van Hoof, E. Bockx, M.J. Hoogmartens, J.C. Mulier, F.J. De Dijcker, W.M. Sansen and W. De Loecker, "The effects of electric currents on ATP generation, protein synthesis, and membrane transport of rat skin", Clin. Orthop. Relat. Res, vol.171, no. pp.264-272, 1982.
  36. K. Cheng and R. Goldman, "Electric fields and proliferation in a dermal wound model: cell cycle kinetics", Bioelec.: J. Bioelec. S., vol.19, no. 2, pp.68-74, 1998. https://doi.org/10.1002/(SICI)1521-186X(1998)19:2<68::AID-BEM2>3.0.CO;2-1
  37. L.C. Kloth, "Electrical stimulation for wound healing: a review of evidence from in vitro studies, animal experiments, and clinical trials", Int. J. L. E. W., vol.4, no. 1, pp.23-44, 2005. https://doi.org/10.1177/1534734605275733
  38. A. Noites, R. Nunes, A.I. Gouveia, A. Mota, C. Melo, A. Viera, N. Adubeiro and J.M. Bastos, "Effects of aerobic exercise associated with abdominal microcurrent: a preliminary study", J. Alt. Comp. Med., vol.21, no. 4, pp.229-236, 2015. https://doi.org/10.1089/acm.2014.0114
  39. A. Noites, J. Pinto, C.P. Freitas, C. Melo, A. Albuquerque, M. Teixeira, F. Ribeiro and J.M. Bastos, "Effects of microcurrents and physical exercise on the abdominal fat in patients with coronary artery disease", Euro. J. Int. Med., vol.7, no. 5, pp.499-507, 2015. https://doi.org/10.1016/j.eujim.2015.06.002
  40. A. Noites, A. Moreira, C. Melo, M. Faria, R. Vilarinho, C. Freitas, P.R. Monteiro, P. Carvalho, N. Adubeiro and M. Amorim, "Acute effects of physical exercise with microcurrent in the adipose tissue of the abdominal region: A randomized controlled trial", Euro. J. Int. Med., vol.9, no. pp.79-85, 2017. https://doi.org/10.1016/j.eujim.2016.11.001
  41. V.N.S. Santos, L.M. Ferreira, E.K. Horibe and I.d.S. Duarte, "Electric microcurrent in the restoration of the skin undergone a trichloroacetic acid peeling in rats", Acta Cirurgica Brasileira, vol.19, no. 5, pp.466-470, 2004. https://doi.org/10.1590/S0102-86502004000500003
  42. M. Ramirez-Ponce, J. Mateos and J. Bellido, "Human adipose cells have voltage-dependent potassium currents", J. Mem. Bio., vol.196, no. 2, pp.129-134, 2003. https://doi.org/10.1007/s00232-003-0631-1
  43. Z.H. Hamida, A.S. Comtois, M. Portmann, J.P. Boucher and R. Savard, "Effect of electrical stimulation on lipolysis of human white adipocytes", App. Phy. Nutr. Meta., vol.36, no. 2, pp.271-275, 2011. https://doi.org/10.1139/h11-011
  44. A. Grizel, G. Glukhov and O. Sokolova, "Mechanisms of activation of voltage-gated potassium channels". Acta Naturae (англоязычная версия), vol.6, no. 4 (23), 2014.
  45. B. Li and W.J. Gallin, "VKCDB: voltage-gated potassium channel database", BMC Bio., vol.5, no. 1, pp.3, 2004. https://doi.org/10.1186/2046-1682-5-3
  46. P.H. Freeman and P.J. Wellman, "Brown adipose tissue thermogenesis induced by low level electrical stimulation of hypothalamus in rats", Brain Res. Bul., vol.18, no. 1, pp.7-11, 1987. https://doi.org/10.1016/0361-9230(87)90026-8
  47. J.-Y. Tano, J. Schleifenbaum and M. Gollasch, "Perivascular adipose tissue, potassium channels, and vascular dysfunction", A. T. Vas. Bio, vol.34, no. 9, pp.1827-1830, 2014. https://doi.org/10.1161/ATVBAHA.114.303032
  48. M. Gollasch, D.G. Welsh and R. Schubert, "Perivascular adipose tissue and the dynamic regulation of Kv7 and Kir channels: Implications for resistant hypertension", Microcirculation, vol.25, no. 1, pp.e12434, 2018. https://doi.org/10.1111/micc.12434
  49. A. Melo, J.S. Moreira, A. Noites, M.F. Couto and C.A. Melo, "Clay body wrap with microcurrent: Effects in central adiposity", App. C. Sci., vol.80, no. pp.140-146, 2013.
  50. D.J. Griffiths, Introduction to electrodynamics. 2005, AAPT.
  51. S. Becker and A. Kuznetsov, "Thermal damage reduction associated with in vivo skin electroporation: A numerical investigation justifying aggressive pre-cooling", Int. J. H. M. T., vol.50, no. 1-2, pp.105-116, 2007. https://doi.org/10.1016/j.ijheatmasstransfer.2006.06.030
  52. D. Miklavcic, N. Pavselj and F.X. Hart, Electric properties of tissues. 2006, Wiley encyclopedia of biomedical engineering New York.
  53. S. Gabriel, R. Lau and C. Gabriel, "The dielectric properties of biological tissues: II. Measurements in the frequency range 10 Hz to 20 GHz", Phy. Med. Bio., vol.41, no. 11, pp.2251, 1996. https://doi.org/10.1088/0031-9155/41/11/002
  54. S. Gabriel, R. Lau and C. Gabriel, "The dielectric properties of biological tissues: III. Parametric models for the dielectric spectrum of tissues", Phy. Med. Bio., vol.41, no. 11, pp.2271, 1996. https://doi.org/10.1088/0031-9155/41/11/003
  55. I.C.o.N.-I.R. Protection, "Guidelines for limiting exposure to time-varying electric and magnetic fields (1 Hz to 100 kHz)". Health physics, vol.99, no. 6, pp.818-836, 2010.
  56. J.-H. Lim, S.D. McCullen, J.A. Piedrahita, E.G. Loboa and N.J. Olby, "Alternating current electric fields of varying frequencies: effects on proliferation and differentiation of porcine neural progenitor cells", Cell. Rep., vol.15, no. 5, pp.405-412, 2013. https://doi.org/10.1089/cell.2013.0001
  57. S.D. McCullen, J.P. McQuilling, R.M. Grossfeld, J.L. Lubischer, L.I. Clarke and E.G. Loboa, "Application of low-frequency alternating current electric fields via interdigitated electrodes: effects on cellular viability, cytoplasmic calcium, and osteogenic differentiation of human adipose-derived stem cells", Tissue Eng. Part C: Methods, vol.16, no. 6, pp.1377-1386, 2010. https://doi.org/10.1089/ten.tec.2009.0751
  58. A. Comsol, "AC/DC Module-User's Guide". COMSOL, vol.3, no. pp.151, 2011.
  59. P.J. Mohr, D.B. Newell and B.N. Taylor, "CODATA recommended values of the fundamental physical constants: 2014", J. Phy. Che. Ref. Data, vol.45, no. 4, pp.043102, 2016. https://doi.org/10.1063/1.4954402
  60. Y.A. Chizmadzhev, A.V. Indenbom, P.I. Kuzmin, S.V. Galichenko, J.C. Weaver and R.O. Potts, "Electrical properties of skin at moderate voltages: contribution of appendageal macropores", Bio. J., vol.74, no. 2, pp.843-856, 1998. https://doi.org/10.1016/S0006-3495(98)74008-1
  61. M. Lean, T. Han and C. Morrison, "Waist circumference as a measure for indicating need for weight management". Bmj, vol.311, no. 6998, pp.158-161, 1995. https://doi.org/10.1136/bmj.311.6998.158
  62. C. Gabriel, A. Peyman and E. Grant, "Electrical conductivity of tissue at frequencies below 1 MHz", Phy. Med. Bio., vol.54, no. 16, pp.4863, 2009. https://doi.org/10.1088/0031-9155/54/16/002
  63. G. Schmid, S. Cecil and R. Uberbacher, "The role of skin conductivity in a low frequency exposure assessment for peripheral nerve tissue according to the ICNIRP 2010 guidelines", Phy. Med. Bio., vol.58, no. 13, pp.4703, 2013. https://doi.org/10.1088/0031-9155/58/13/4703
  64. E. Saenz, P.M. Ikonen, R. Gonzalo and S.A. Tretyakov, "On the definition of effective permittivity and permeability for thin composite layers", J. App. Phy., vol.101, no. 11, pp.114910, 2007. https://doi.org/10.1063/1.2743817
  65. M. Ramirez-Ponce, J. Acosta, J. Bellido and J. Mateos, "Noradrenaline modulates the electrical activity of white adipocytes by a cAMP-dependent mechanism", J. Endo., vol.159, no. 3, pp.397-402, 1998. https://doi.org/10.1677/joe.0.1590397
  66. M. Ramirez-Ponce, J. Mateos and J. Bellido, "Insulin increases the density of potassium channels in white adipocytes: possible role in adipogenesis", J. Endo., vol.174, no. 2, pp.299-307, 2002. https://doi.org/10.1677/joe.0.1740299
  67. A. Haynes, I. Kersbergen, A. Sutin, M. Daly and E. Robinson, "A systematic review of the relationship between weight status perceptions and weight loss attempts, strategies, behaviours and outcomes", Obesity Rev., vol.19, no. 3, pp.347-363, 2018. https://doi.org/10.1111/obr.12634
  68. S.P. Messier, A.E. Resnik, D.P. Beavers, S.L. Mihalko, G.D. Miller, B.J. Nicklas, P. DeVita, D.J. Hunter, M.F. Lyles and F. Eckstein, "Intentional Weight Loss for Overweight and Obese Knee Osteoarthritis Patients: Is More Better?". Arthritis care & research, no. 2018.
  69. S. Grimnes, "Impedance measurement of individual skin surface electrodes", Med. Bio. Eng. Com., vol.21, no. 6, pp.750-755, 1983. https://doi.org/10.1007/BF02464038