JACN
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

This Article
Right arrow Abstract Freely available
Right arrow Figures Only
Right arrow Full Text (PDF)
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by De Lorenzo, A.
Right arrow Articles by Volpe, S. L.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by De Lorenzo, A.
Right arrow Articles by Volpe, S. L.
Journal of the American College of Nutrition, Vol. 22, No. 6, 546-549 (2003)
Published by the American College of Nutrition

Original Research

Body Cell Mass Measured by Total Body Potassium in Normal-Weight and Obese Men and Women

Antonino De Lorenzo, MD, Angela Andreoli, MD, Paola Serrano, MD, Nicolantonio D’Orazio, MD, Valerio Cervelli, MD and Stella L. Volpe, PhD

Human Nutrition Unit (A.D.L., A.A.), Rome
Plastic Surgery Unit (V.C.), Rome
University of Rome "Tor Vergata" and Whole Body Counter National Council of Research (A.D.L., A.A.), Rome
Lega Italiana per la Lotta contro i Tumori, Reggio Calabria (P.S.)
Human Nutrition Unit, University of Chieti (N.D’O.), Amherst, Massachusetts
Department of Nutrition, University of Massachusetts, Amherst, Massachusetts (S.L.V.)

Address reprint requests to: Angela Andreoli, MD, Human Nutrition Unit, Via Montpellier 1, University of Rome "Tor Vergata," 00173 Rome, ITALY. E-mail: angela.andreoli{at}uniroma2.it


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 CONCLUSION
 REFERENCES
 
Objective: Total body potassium (TBK) concentration is linearly correlated with the size of the body cell mass (BCM). The aim of this study was to compare BCM in normal-weight and obese individuals.

Methods: 271 individuals (207 males, 64 females), 20 to 67 years of age, participated in this study. Subjects were separated by body mass index (BMI): BMI < 25 kg/m2 (BMI-L) and BMI > 25 kg/m2 (BMI-H). 40K was assessed using a whole-body counter and BCM was calculated.

Results: BCM and TBK were significantly greater in men, with a trend to be greater in women in BMI-H compared to men in BMI-L. TBK/body weight was significantly lower, while TBK/height was significantly greater for men and women in BMI-H compared to men and women in BMI-L. Fat-free mass (FFM) was significantly greater for men in BMI-H, with no significant differences in FFM between the two groups of women.

Conclusions: The healthy obese subjects in the present study had a greater BCM than the non-obese subjects. These results indicate that it is important to assess BCM in obese individuals because it could influence the type of weight loss regimen that will be used in order to preserve BCM.

Abbreviations: body cell mass • body fat • fat free mass • obesity • total body potassium


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS
 CONCLUSION
 REFERENCES
 
Human obesity can occur in the face of positive energy balance, and thus it is considered a nutritional disorder. It has been reported that approximately 40% of excess body weight in obese children, adolescents, and adults consists of lean body mass, although some have reported percentages similar to normal-weight individuals [1]. Such data can be interpreted to suggest that most individuals are over-nourished. Obesity has been associated with health complications such as "Syndrome X" or the "Metabolic Syndrome," diabetes mellitus and cardiovascular disease, especially when the excess body fat is stored in the deep abdominal region [2–5].

Increased body fat has been related to slower walking speeds and impaired functional capacity, while higher lean body mass has been linked to increased grip strength [6]. These findings imply that fat mass negatively affects some aspects of physical performance and functional capacity [6]. Therefore, assessment of body composition is an important measure in all ages, and can assist in identifying potential risk factors.

An approach to assessing body composition is to measure body cell mass. Body cell mass is defined as the metabolically active portion of the body [7]. Presently, the "gold standard" for assessing body cell mass is via measurement of the naturally occurring isotope 40K [8]. Total body potassium concentration is linearly correlated with the size of the body cell mass [8]. An accurate evaluation of body cell mass would prove useful for establishing an individual’s state of health or disease over time, possibly assisting with the prevention of obesity.

Thus, the aim of this study was to compare body cell mass, using whole-body potassium counting, in normal-weight and obese men and women based on the body mass index standards established by the World Health Organization [9] and the National Institutes of Health [10].


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 CONCLUSION
 REFERENCES
 
Subjects
This study was first approved by the Ethical Committee of the University of Rome "Tor Vergata". Each subject gave verbal and written informed consent prior to participation. Two hundred and seventy-one individuals (207 males and 64 females), between 20 to 67 years of age, participated in this study. These individuals were employees at a nuclear power plant in Italy. All individuals were examined by the same physician and were determined to be in good health, without any underlying diseases such as diabetes mellitus, cardiovascular disease, or the like. Unfortunately, we do not have data on physical activity levels, medication/drug use, overall diet, or smoking habits, which can all affect body composition. Although this was a limitation of the study, the main purpose of the study was to assess body cell mass between normal-weight and obese individuals, which could then lead to controlled, longitudinal studies in the future.

Body Weight, Height, Body Mass Index
All body composition techniques were administered to each subject on the same morning. On the test day, subjects were in a post-absorptive state (fasted for at least 10 to 12 hours). Body weight (Invernizzi, Rome, Italy) and height (stadiometer; Invernizzi, Rome, Italy) were measured to the nearest 1 kg and 0.5 cm, respectively. Body mass index (BMI) was calculated using the formula: body weight (kg)/height (m2). Subjects were grouped by BMI: those with a BMI < 25 kg/m2 were considered normal weight, and those with a BMI > 25 kg/m2 were considered obese [9,10]

40K, Total Body Potassium, Body Cell Mass
The measurement of 40K was assessed using a whole-body counter, surrounded by a cell of 10 cm thick lead bricks, 2.5 m wide and 3 m high, with a door whose entrance was formed by a 22 cm thick iron slab [8,11,12]. The room was continuously ventilated. A single 20.3 x 10.2 cm thallium-activated sodium iodine crystal was positioned above the subject, who was measured in a sitting position for 20 minutes. During the measurements, subjects were dressed in paper pajamas. Total body potassium (TBK) was calculated by using the formula: 40K x 8.4746 [13]. Body cell mass (BCM) was calculated from TBK by using the formula of Moore et al. [7]: BCM (kg) = 0.00833 x TBK (mmol). TBK/height and TBK/body weight were also calculated in order to assess TBK relative to these variables [14].

Fat-free mass (FFM) was calculated using the following formulas (13):


Statistical Analyses
Differences between normal-weight and obese individuals for all variables were calculated using t tests. Analyses were not conducted between genders, only within genders of differing BMIs. The data were analyzed using the Statistical Program for the Social Sciences (SPSS) Version 9.0 for Windows statistical software. Statistical significance was set a priori at p = 0.05 level of probability. All values are expressed as means ± standard deviation (SD).


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
CONCLUSION
 REFERENCES
 
Table 1 illustrates subject characteristics. There were no significant differences in age between the two male groups and the two female groups. Height was significantly lower in women with a BMI > 25 kg/m2 compared to women with a BMI < 25 kg/m2. Body weight and BMI were significantly greater in men and women with a BMI > 25 kg/m2 compared to men and women with a BMI < 25 kg/m2. Correlations between BMI and BCM were r = 0.276 (p = 0.01) for men and r = 0.311 (p = 0.05) for women (Fig. 1).


View this table:
[in this window]
[in a new window]
  		Table 1. Subject Characteristics

 


View larger version (26K):
[in this window]
[in a new window]
  		Fig. 1. Scatter plot of the correlation between BCM and BMI for men and women. r = 0.276 (p = 0.01) for men, r = 0.311 (p = 0.05) for women.

 
Table 2 lists the body composition values for all subjects. BCM and TBK were significantly greater in men with a BMI > 25 kg/m2 compared to men with a BMI < 25 kg/m2. There was a trend for BCM and TBK to be greater in women with a BMI > 25 kg/m2 compared to women with a BMI < 25 kg/m2. TBK/body weight was significantly lower for men and women with a BMI > 25 kg/m2 compared to men and women with a BMI < 25 kg/m2. TBK/height was significantly greater for men and women with a BMI > 25 kg/m2 compared to men and women with a BMI < 25 kg/m2. Although fat free mass (FFM) was significantly greater for men with a BMI > 25 kg/m2, there were no significant differences in FFM between the two groups of women. Fat mass (FM) and percent body fat (%BF) were significantly greater for men and women with a BMI > 25 kg/m2 compared to men and women with a BMI < 25 kg/m2.


View this table:
[in this window]
[in a new window]
  		Table 2. Body Cell Mass (BCM), Total Body Potassium (TBK), TBK/Body Weight, TBK/Height, Fat Free Mass (FFM), Fat Mass (FM), and Percent Body Fat (%BF) of All Subjects

 

   DISCUSSION
 
Obesity has become a prevalent problem throughout the world and is considered a multi-factorial disorder, which includes an imbalance in energy expenditure and energy intake. Although assessing body weight provides one marker of obesity, evaluating body composition must be considered when assessing obese individuals [15].

A better indicator of body composition is the evaluation of BCM, because this estimates the metabolically active tissue in the body [7]. Thus, the aim of this study was to compare BCM, using whole-body potassium counting, in obese and normal-weight individuals.

Body weight, BMI, BCM, TBK, TBK/height, FM, and %BF were greater in obese compared to normal-weight subjects. The results of this study establish the importance of assessing body composition, especially BCM in obese individuals, because the metabolically active tissue (BCM) was greater in the obese subjects, which needs to be preserved with weight loss. Engelhart et al. [16] reported a 3% loss in BCM in obese patients with rheumatoid arthritis who were placed on a 12-week weight loss program, which consisted of reduced energy intake, increased protein intake, and moderate physical training. They stressed the importance of maintaining BCM with weight loss in obese individuals.

In contrast to our results, Leone et al. [17] reported that post-obese subjects who had undergone gastrointestinal surgery had a lower BCM compared to never-obese subjects. They stated that "these observations are important for interpreting body weight, body composition, and metabolic data of obese subjects who lost weight and maintained their weight loss over the long term" [17]. Our subjects were observed at one point in time, were healthy, and did not undergo a weight loss regimen. A long-term intervention study on obese subjects would shed new light on optimal methods of preserving BCM over time.

Although we found differences in BCM between normal-weight and obese subjects, others found no differences in BCM (assessed by bioimpedance analysis) between obese and morbidly obese subjects, despite observing significant differences in FM between the groups [18].

Nonetheless, in the present study, normal-weight and obese subjects were compared, using whole-body potassium counting, which provides a more accurate assessment of BCM than bioimpedance analysis. It is relevant to monitor changes during weight loss in order to minimize losses; however, whole-body potassium counting is expensive, time-consuming, not generally available, and is not easily applicable in the daily routine practice, so easier methods need to be identify to monitor changes in BCM in weight loss program.


   CONCLUSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 CONCLUSION
REFERENCES
 
In conclusion, the healthy obese subjects in the present study had a greater BCM than the non-obese subjects. The results of this study indicate that it is important to assess BCM in obese individuals because it could influence the type of weight loss regimen that will be used. Preservation of BCM is vital since it maintains metabolic rate, which will result in successful weight loss over the long-term. Longitudinal studies need to be conducted to evaluate the effects of different weight loss regimens on BCM in obese subjects.

Received November 25, 2002. Accepted July 9, 2003.


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 CONCLUSION
 REFERENCES
 

  1. Forbes GB, Welle SL: Lean body mass in obesity. Int J Obes7 :99 –107,1983 .[Medline]
  2. Landers P, Wolfe MM, Glore S, Guild R, Phillips L: Effect of weight loss plans on body composition and diet duration. J Okla State Med Assoc95 :329 –331,2002 .[Medline]
  3. Astrup A, Finer N: Redefining type 2 diabetes: ‘diabesity’ or ‘obesity dependent diabetes mellitus’? Obes Rev1 :57 –59,2000 .[Medline]
  4. Bosello O, Zamboni M: Visceral obesity and metabolic syndrome. Obes Rev1 :47 –56,2000 .[Medline]
  5. Tremblay A, Doucet E: Obesity: a disease or a biological adaptation? Obes Rev1 :27 –35,2000 .[Medline]
  6. Sternfeld B, Ngo L, Satariano WA, Tager IB: Associations of body composition with physical performance and self-reported functional limitation in elderly men and women. Am J Epidemiol156 :110 –121,2002 .[Abstract/Free Full Text]
  7. Moore FD, Olesen KH, McMurray JD, Parker HV, Ball MR, Boyden CM: "The Body Cell Mass and Its Supporting Environment." Philadelphia: WB Saunders,1963 .
  8. Pierson Jr RN, Lin DHY, Phillips RA: Total-body potassium in health: effects of age, sex, height, and fat. Am J Physiol226 :206 –212,1974 .[Free Full Text]
  9. World Health Organization: "Obesity: Preventing and Managing the Global Epidemic. Report on WHO Consultation on Obesity, Geneva, 3–5, June, 1997." WHO/NUT/NCD/98 1. Geneva: WHO,1998 .
  10. National Heart, Lung, and Blood Institute, National Institutes of Health: "Calculate Your Body Mass Index." Accessed at: http://www.nhlbisupport.com/bmi/bmicalc.htm
  11. Cohn SH, Vartsky D, Yasumura S, Vaswani AN: Indexes of body cell mass: nitrogen versus potassium. Am J Physiol (Endocrinol Metab)7 :E305 –E310,1983 .
  12. De Lorenzo A, Candeloro N, Andreoli A, Deurenberg P: Determination of intra-cellular water by multi-frequency bioelectrical impedance. Ann Nutr Metab39 :177 –184,1995 .[Medline]
  13. Forbes GB: "Human Body Composition." New York: Springer,1987 .
  14. Kehayias JJ, Fiatarone MA, Zhuang H, Roubenoff R: Total body potassium and body fat relevance to aging. Am J Clin Nutr66 :904 –910,1997 .[Abstract/Free Full Text]
  15. Tershakovec AM, Kuppler KM, Zemel B, Stallings VA: Age, sex, ethnicity, body composition, and resting energy expenditure of obese African American and white children and adolescents. Am J Clin Nutr75 :867 –871,2002 .[Abstract/Free Full Text]
  16. Engelhart M, Kondrup J, Hoie LH., Andersen V, Kristensen JH, Heitmann BL: Weight reduction in obese patients with rheumatoid arthritis, with preservation of body cell mass and improvement of physical fitness. Clin Exp Rheumatol14 :289 –293,1996 .[Medline]
  17. Leone PA, Gallagher D, Wang J, Heymsfield SB: Relative overhydration of fat-free mass in postobese versus never-obese subjects. Ann NY Acad Sci904 :514 –519,2000 .[Medline]
  18. Verga S, Buscemi S, Caimi G: Resting energy expenditure and body composition in morbidly obese, obese and control subjects. Acta Diabetol31 :47 –51,1994 .[Medline]




This Article
Right arrow Abstract Freely available
Right arrow Figures Only
Right arrow Full Text (PDF)
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by De Lorenzo, A.
Right arrow Articles by Volpe, S. L.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by De Lorenzo, A.
Right arrow Articles by Volpe, S. L.

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS