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News - Bioimpedance testing

By Christine Bailey MSc PGCE MBANT

Maintaining a healthy body weight and reducing excess body fat are associated with long term health benefits, as well as reducing incidence of chronic diseases. New bioimpedance devices offer a simple clinical tool for empowering clients to achieve long term health goals. Christine Bailey explains how it could benefit your practice.

Chronic diseases, such as type II diabetes, heart disease, stroke and obesity are claiming more lives than any other illnesses in the UK(1) and cause a tremendous burden on our healthcare provision. For many clients, losing weight, improving fitness or achieving a greater sense of health and vitality are top of their list of health goals. However, keeping clients focused and motivated while monitoring treatment response, requires tools suitable for the clinical setting(2). Bioimpedance analysis (BIA) is a scientifically-validated technique which evaluates body composition and includes biomarkers of health, including muscle, fat and energy production.

BIA instruments have become increasing popular for estimating body composition in many professional settings; particularly hospitals, primary care clinics and health and fitness centres. In hospitals they are also used for monitoring patients after surgery and to evaluate malnutrition or abnormal hydration(3). Over recent years, a range of BIA devices have been developed for the home market, as well as instruments suitable for practitioner use.

Clinically, BIA provides the practitioner with a valuable tool to help identify patients at greatest health risk and provides additional evidence of the success or failure of treatment programmes. It is particularly useful for the following:

  • Obese/overweight clients and those following weight loss programmes;
  • Athletes and sports enthusiasts wishing to increase muscle mass and monitor training programmes;
  • Clients with long term chronic conditions, such as diabetes, metabolic syndrome and heart disease;
  • Clients wishing to actively improve their health and track body composition changes;
  • Older clients seeking to support health, cellular function(4) and muscle mass;
  • Clients with conditions associated with sarcopenia (loss of muscle mass).

Practitioner instruments differ from bioimepdance scales and hand-held devices, in that they involve four electrode or tetrapolar measurements. The reliability of BIA depends on the equation used to predict body composition and the parameters included in the formula (weight, height, sex, age, race, etc.)(5). Formulas have been  developed for specific populations which means the device can be used with children, adults, obese clients(6) and those from a range of ethnic backgrounds(7). In addition, measurements are included to assess fluid status and cellular health and function(8). Various studies have shown BIA to be a safe, valid and reliable method of body composition assessment(9). As BIA does not provide information on regional fat distribution, combining BIA with measures of central adiposity, such as waist circumference and waist-to-hip ratio, provides the practitioner with a better appraisal of health risk.

Undertaking a measurement is simple and quick and can easily be incorporated into the client’s consultation. The device includes four leads which are attached, via small pads, to the client’s hands and feet. A safe, painless, low voltage electrical current is passed through the body. The ‘impedance’ can be defined as the strength and speed of an electrical signal travelling through the body. BIA is based on the fact that lean tissues, such as muscle and blood, contain high levels of water and electrolytes and, therefore, act as a conductor of an electrical signal. Fat tissue, in contrast, acts as a resistor to the flow of an electrical signal. Increasing levels of fat mass result in a higher impedance value and correspond to higher levels of body fat. Using BIA software, body composition reports and printouts on hydration status and cellular health can be generated. These enable clients not only to view a summary of their body composition and health risk, but are useful for fostering compliance with treatment and preventative interventions.  Measurements can be repeated at follow-up consultations to track changes, tailor treatment and keep the client motivated.

In view of the current obesity epidemic and demand for effective weight management schemes, BIA offers a safe, inexpensive tool with the added advantage of being easily incorporated into lifestyle and dietary programmes(10). What’s more, BIA has many more uses than just disease management.  It is an ideal tool for any client seeking to take an active role in improving their health and wellbeing, long term. 

Case Study

Mark* came to see me for a nutritional consultation, as he was concerned about his family history of cardiovascular disease and recent weight gain. 

At 37 years old, with two young children and a stressful city job, he wanted to improve his health long term, as well as losing weight and improving fitness. Mark set himself a target of losing a stone in weight, improving muscle mass and building up his fitness, in order to complete a half marathon later in the year. 

At his first visit, Mark weighed 90kg with a waist measurement of 102.5cm and a BMI of 27.8.  His percentage body fat was 23.9% and active tissue mass 42.1%. 

I devised a new eating plan and supplement programme for Mark combined with fitness training, including weights and cardio. Mark was already very motivated but seeing the printout of his baseline body composition helped him stay on track. 

After three weeks Mark had reached his target weight, losing 7.7kg, over one stone. More importantly he had reduced his percentage body fat to 17.9% while active tissue mass (muscle) had increased to 46%. His BMI was now 25.4 and he had reduced his waist measurement to 99cm. Mark was thrilled with his success and, as a bonus, was experiencing improved sleep and energy levels. He went on to complete his half marathon with no soreness or injuries. He has since further increased his muscle mass and is training for several more half marathons. 

*Name of client has been changed 

Christine is a qualified nutritionist, graduating with a First Class Honours degree, as well as being an experienced and trained professional chef, food and health consultant and journalist, with over 16 years of experience. She was awarded Coeliac Chef of the Year 2008 by the Coeliac Society. She is a member of the Guild of Health Writers and writes regularly for many national magazines and websites on food, health, family and women’s health. She is a cookery teacher, Nutritional Advisor and Nutrition and Health Trainer for various corporate clients, cookery schools, local authorities’ establishments and nutrition colleges. She is also author of several recipe and health books. 

Article References

1.Yach D et al. The global burden of chronic diseases: overcoming impediments to prevention and control JAMA 2004 Jun 2:291 (21) 2616-22 2.Ricciardi, R and Talbot, L. Use of bioelectrical impedance analysis in the evaluation, treatment and prevention of overweight and obesity. Journal of the American academy of Nurse Practitioners 19 (2007) 235-241 3.Maisonneuve N.,Genton L, Karsegard V, Kyle U, Dupertuis Y., Pichard C. Bio-impedance analysis: Screening of denutrition in hospitalized patients Nutrition clinique et. Metabolisme 2003 Volume 17, Number 4, pp. 227-236(10) 4.Kotler, D, Rosenbaum, K, Allison D, Wang, J. And Pierson R. Validation of Bioimpedance Analysis as a Measure of Change in Body Cell Mass as Estimated by Whole-Body Counting of Potassium in Adults Journal of Parenteral and Enteral Nutrition, 1999 Vol. 23, No. 6, 345-349 5.D Gallagher, SB Heymsfield, M Heo, SA Jebb, PR Murgatroyd and Y Sakamoto. Healthy percentage body fat ranges: an approach for developing guidelines based on body mass index1–3. Am J Clin Nutr 2000; 72:694–702. 6.Segal K.R., van Loan M., Fitzgerald P.I., Hodgdon J.A. & van Italie T.B. Lean body mass estimation by bioelectrical impedance methods; a four-sit cross validation study. American Journal of Clinical Nutrition 47:1988 pp 7-14 7.Cordain L., Whicker R. & Johnson J. Body composition determination in children using bioelectrical impedance. Growth Development & Aging 52:1988 pp37-40 8.A Bosy-Westphal, S Danielzik, RP Dörhöfer, A Piccoli, and MJ Müller. Patterns of bioelectrical impedance vector distribution by body mass index and age: implications for body-composition analysis1–Am J Clin Nutr 2005;82:1358. 9.Kyle UG et. al. Bioelectrical impedance analysis part II. Utilisation in clinical practice. Clinical Nutrition 23(6) 1430-1453 10.Schiltz B et. al. A science based, clinically tested dietary approach for the metabolic syndrome. Metab. Syndr Relat Disord 2009 Jun 7(3) 187-92

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