Which assessment technique may be used to determine the size density and location of an organ?

Underwater Weighing

Hydrodensitometry, or underwater weighing, is the classic approach to determining body composition. Based on principles promulgated by Archimedes, the technique generates knowledge of two compartments, the fat mass and the fat-free mass. When a body is submerged in water, there is a buoyant counterforce equal to the weight of the water that is displaced. Because bone and muscle have greater density than water, a person with a larger percentage of fat-free mass will weigh more in the water. Conversely, a larger amount of fat mass will make the body lighter in the water. The individual is measured for the amount of water displacement by submerging in water while sustaining a 30-sec forced expiration. This step is required because air trapped in the lungs also contributes to the amount of water displaced by the subject. The underwater weight is recorded at the end of the forced expiration. This is then compared to the subject's weight in air to obtain body density. Estimates of the fat body and the fat-free body densities are used to calculate the size of these two body composition compartments. The fat-free mass is a heterogeneous compartment that could be further subdivided according to its primary constituents: water (73.8%), protein (19.4%), and mineral (7.8%). Although not feasible for implementation in field studies, the hydrodensitometry approach is used as the gold standard for validating other methods [85–87].

This methodology is compromised because densitometry equations were developed from direct analysis of white cadavers [85] and will lead to the systematic underestimation of relative fatness in American Indian women, black women, and Hispanic women. The fat-free body density in these race/ethnic groups exceeds the assumed value of 1.1 g/ ml [88].

Hydrodensitometry

Hydrodensitometry or underwater weighing, considered for many years the gold standard for measuring body fat, is based upon the Archimedes principle whereby the volume of a mass is equal to the volume of liquid displaced by that solid. Thus, BW in the air and water is measured to determine body density (Db). Percent fat is determined with the equations described by anthropometry pioneers Siri and Brozek et al. as

Siri:percent fat= 4.95/Db−4.5

Brozeketal.:percent fat=4.570/Db−4.142.

Fat mass and FFM are then calculated. Residual lung volume must be determined prior to or during underwater weighing using either the helium or nitrogen dilution methods. Fat and FFM values in adults are assumed to have reference values (0.9007 g/ml and 1.10 g/ml, respectively), which may not be accurate in women, athletes, or the elderly. Furthermore, this technique assumes adequate subject hydration, a fasted state, and a volume of intestinal gas.

3.4 Measurement Tools

Body fat can be measured with several tools such as bioelectrical impedance analysis (BIA), dual-energy X-ray absorptiometry (DEXA), hydrodensitometry, and skin-fold thickness. Although these tools are excellent for assessing excess body fat, they have limitations, including availability, expense, and lack of pediatric standards. In some countries, the population-specific percentage-weight-for-height (PWH) is used to screen children for obesity.

The most widely accepted measure to identify US children and adolescents > 2 years of age who are overweight or obese is the body mass index (BMI) plotted on the Center for Disease Control (CDC) charts [20]. It is easy to use and correlates fairly well with the percentage of body fatness; however, it does not take into consideration lean muscle mass. The BMI may not be a reliable tool to accurately assess children of different ethnic groups due to their body composition [6]. Because a global measure for identification of children who are overweight and obese has been difficult to establish and has not been standardized worldwide, the actual number of children at risk may be underreported [21, 22]. Until a universal, standardized measure is established, BMI is the accepted identification tool. Clinical practice guidelines (2017) from The Endocrine Society recommend this be plotted at least annually, during well or sick-child visits, for children over the age of 2 years [20]. The BMI is not used for children under 2 years of age, instead the gender-appropriate, weight-for-length growth chart is used to follow their growth more accurately. The child's weight and height should be plotted and evaluated at each office visit regardless of age. Careful inspection of advancing weight trajectory should occur. A weight crossing more than 2 percentiles on the curve should prompt the nurse to screen for behaviors impacting weight, particularly physical activity and nutrition, and to intervene early to slow continued weight gain. It is easier to prevent obesity than to provide the intensive treatment needed once a child reaches an obese level.

Categorization of weight based on BMI differs for children and adults. For adults, a BMI > 25 kg/M2 is defined as overweight. A BMI > 30 kg/M2 is defined as obese [23]. For children, the BMI category is based on age and gender. Children with a BMI > 85th but < 95th percentile for age and gender are considered overweight. Those with a BMI > 95th percentile are considered obese [24]. Extreme obesity in children is defined as a BMI > 120% of the 95th percentile, or 35 kg/M2 [20].

Nurses can use the BMI in most settings because they will most likely have access to a scale and a way to measure height. Nurses may, however, lack the knowledge and experience to identify obesity. Moyers et al. found that only a third of school nurses used BMI to assess for obesity, with half of nurses using “eyeball analysis”, and four nurses did not screen for obesity at all [11]. When the BMI is not used as part of the child's evaluation, at-risk children may be overlooked for intervention. Discussing the BMI chart with families can be a useful way for the nurse to help the family understand the seriousness of the child's weight and how it relates to potential comorbid conditions. The nurse can then discuss lifestyle changes to improve health and decrease the risk for comorbidities. Regardless of the measure used to identify overweight and obese children, the nurse needs to be familiar with the tool being used, understand how to use it accurately and effectively, and include it as part of the child's evaluation in any setting [11]. They can then facilitate access to health care for treatment.

Because children spend the major part of the day in school, this is a primary setting where nurses can positively impact health outcomes [3]. School nurses already share other important health information with families, which make them an ideal resource to share obesity screenings. However, only a third of nurses agree that schools should be responsible for reporting these findings to families [25]. This may be problematic because less than 40% of nurses obtain weight, height, and BMI information on all students, as well as follow through with families of at-risk children. The ratio of students to nurses available may also present a barrier to obtaining the required information.

Nurses in the pediatric primary care setting play a role in identifying children at risk for being overweight and obese. Nurses in the pediatric office should obtain weight and height, calculate BMI, and plot all measurements accurately on the gender-specific growth chart as part of the well-child visit, as well as most visits in-between, to evaluate for normal growth and development. Frequent assessment of these measures allows for early identification of rapid increases in weight, which can be addressed before the weight gain becomes significant. Educating parents about healthy lifestyles, including age-appropriate portion sizes and physical activity, and using BMI at each well-child visit are important tasks for nurses in primary care.

Nurses working in the community are a valuable resource when it comes to screening for overweight and obese children. Churches and community centers are often venues where children participate in activities and could benefit from having a nurse available to do occasional health screenings and provide recommendations for further evaluation of children who fall into at-risk categories.

Hospitals have been overlooked by the nurse as a resource for identification of obesity. Many children are hospitalized each year, either in a children's hospital, on a pediatric unit in an adult hospital, or on a general hospital floor. Regardless of the reason for the admission, there should be an evaluation for obesity risk. In the hospital setting, it is important to identify overweight and obese children to ensure that the best care is provided to them. They may require special-sized equipment, such as a bariatric bed, scale, wheelchair, bedside commode, linens, and gowns to accommodate the weight to make their hospital stay safe and more comfortable. Nurses are in an excellent position to facilitate obtaining the necessary supplies. It is also important to make sure the blood pressure cuff is of adequate size to obtain accurate blood pressure readings during the stay. Having a best practice alert for obese children in the hospital setting may also be an opportune time to address the weight concern and refer them to an intensive weight management program. The nurse may also address any specialized dietary needs during the hospital stay to promote healthy nutrition.

Conclusions

The amount and nature of adipose tissue of a child at which morbidity acutely and/or later in life increases is determined on an actuarial basis. Direct measurements of body fat, for example hydrodensitometry, bioimpedance, or DEXA, is only useful in a research context. In contrast, body mass index (BMI) is easy to calculate and is widely accepted to define obesity in children and adolescents clinically and for practical purposes. An increased risk of death from cardiovascular disease in adults has been found in subjects whose BMI had been greater than the 75th percentile as adolescents. Childhood obesity seems to also substantially increase the risk of subsequent morbidity whether or not obesity persists into adulthood. The genetic basis of childhood obesity has been elucidated to a large extent through the discovery of leptin, and the increasing knowledge on the role of neuropeptides such as POMC, neuropeptide Y (NPY) and the melanocyte concentrating hormone receptors (for example, MC4R) and the discovery of FTO as an obesity risk allele. However, environmental/exogenous factors largely contribute to the development of a high degree of body fatness early in life. Twin studies suggest that approximately 50% of the tendency toward obesity is inherited while 50% are related to socioeconomic and life style factors. There are numerous disorders including a number of endocrine disorders (Cushing syndrome, hypothyroidism, etc.) and genetic syndromes (Prader–Labhard–Willi syndrome, Cohen and Alström syndrome, Bardet–Biedl syndrome, etc.) that are associated with an increased body fat mass. Usually, a simple clinical diagnostic algorithm allows for the differentiation between primary or secondary obesity. Among the most common sequelae of primary childhood obesity are hypertension, dyslipidemia, impaired insulin sensitivity, back pain and psychosocial problems such as behavior problems, exclusion from social participation and attention deficit hyperactivity and depression. Therapeutic strategies include psychological and family therapy, lifestyle/behavior modification and nutrition education. The role of regular exercise and exercise programs has to be emphasized. Surgical procedures and drugs used in adult obesity are still not generally recommended in children and adolescents with obesity. As obesity is the most common chronic disorder in industrialized societies, its impact on individual lives as well as on health economics has to be recognized more widely. Finally, one should aim to increase public awareness of the ever increasing health burden and economic dimension of the childhood obesity epidemic that is present around the globe. It is clear that we have to strengthen our efforts in respect to investigate prevention and interventions that will work both on an individual and a societal level. The questions that are to be asked are the questions that need to be answered in order to improve quality of life of patients, reduce suffering from the disease, and increase the survival of patients and importantly to increase our chances to successfully prevent obesity at an early age.

It is now well known that obesity is the most common chronic disorder in industrialized societies. In some countries, the prevalence of obesity in childhood and adolescence has become higher than that of the allergic disorders including both asthma and eczema. As has been said, childhood obesity is associated with substantial comorbidity and late sequelae. While diagnostic strategies are clear and straight forward, treatment remains difficult and frustrating both for the patient, family and the multidisciplinary team caring for children with obesity. In conclusion, much more attention should be given to prevention and the development of preventive strategies at all ages. Prevention should, in any case, start very early in life possibly during pregnancy and fetal life. New drugs are being developed that promise to be useful for treatment and secondary prevention. However, no data are available for the use of such agents in childhood and adolescence. This notion also applies to the treatment of type 2 diabetes mellitus and comorbid conditions that frequently accompany type 2 diabetes and/or obesity in children and adolescents. Finally, public awareness of the ever increasing health burden and economic dimension of the childhood obesity epidemic has to be asked for and also has to be insisted on repeatedly and constantly. Political measures have to be taken to ensure and enable healthy lifestyles at an early age and to combat the financial interest of industries that may harm children׳s health.

18.3.2 Densitometric Methods

Densitometric methods utilize the principle that body density can be determined as body mass divided by volume. Body density is then used to estimate fat-free mass, fat mass and percentage body fat using conversion formulae. The method is based on several assumptions, including the assumption that the densities of the major tissue compartments (density of fat = 0.900 g/cm3 and fat-free mass = 1.100 g/cm3) are relatively constant across individuals. However, these constants vary with growth, maturation, illness, degree of obesity and aging. The Siri and Brozek formulae (Table 18.3) are the most widely used conversion formulae in adults. Lohman28 and more recently Wells29 have published age- and sex-specific constants for children to be used in equations similar to that of Siri, which take into account the chemical immaturity of the growing child. In children and adolescents, the chemical composition of the body changes, particularly with respect to the decreasing water and increasing mineral content of fat-free mass. For example, the density of fat-free mass in 8-year-old boys is 1.0877 g/cm3 and for girls it is 1.0900 g/cm3,29 as opposed to the value for adults of 1.100 g/cm3.

Table 18.3. Prediction of body fat using body density measurements

Hydrodensitometry, or underwater weighing, was at one time the most readily available criterion method for assessment of body composition (fat-free mass and fat mass). It has been used mainly in adults and adolescents, and can be used in children (≥8 years) who are healthy, ambulatory and have normal cognitive status. Body volume is determined from measurement of body mass in air and while immersed in water using Archimedes' principle. According to Archimedes' principle, the apparent weight of an object immersed in water, relative to its weight in air, is decreased by an amount equal to the weight of the displaced water. One milliliter of water has a mass almost exactly equal to one gram. Therefore, the difference between the mass in air and the mass under water (in grams) is equivalent to the volume (in milliliters) of the object. The density is then calculated as mass divided by volume. Corrections are needed for the volume of air in the lungs and intestines, and for the density of air and water.

Air-displacement plethysmography is similar to hydrodensitometry in using mass and volume to measure body density. This method uses the displacement of air to estimate body volume. Figure 18.1 shows a Bod Pod® (Life Measurement Instruments, Concord, CA, USA) body composition analyzer, containing a two-compartment chamber of known size. Using a pulsating diaphragm between the two chambers to vary the pressure, the displacement of air when a subject is seated in the outer chamber is measured. A breathing apparatus is built into the device to estimate lung volume for a more accurate estimate of body density. Once body density is determined, the calculations are similar to those for hydrodensitometry. A similar device, the PeaPod, is used to determine body composition in infants.

One of the major sources of bias in the densitometric methods involves the assumptions about the water and mineral content of the fat-free mass. Multicompartment approaches that include other measures such as total body water (TBW) to measure the water content of the fat-free mass, and dual-energy absorptiometry to measure bone mineral content, greatly improve the accuracy of body composition estimates, especially in growing children.30

Models in Body Composition

The use of models in the assessment of body composition allows for the indirect assessment of compartments in the body. Typically, a compartment is homogenous in composition (for example, fat), however, the simpler the model the greater the assumptions made and the greater the likelihood of error. The sum of components in each model is equivalent to body weight (Figure 1). These models make assessments at the whole-body level and do not provide for regional or specific organ/tissue assessments.

The basic two-compartment (2C) model (Table 1) is derived from measuring the density of FFM by hydrodensitometry and subtracting FFM from total body weight thereby deriving fat mass (body weight−FFM=fat mass). FFM is a heterogeneous compartment consisting of numerous tissues and organs. A 2C approach becomes inadequate when the tissue of interest is included within the FFM compartment. Nevertheless, the 2C model is routinely and regularly used to calculate fat mass from hydrodensitometry, total body water, and total body potassium.

Table 1. Multicompartment body composition models

Db, body density; TBW, total body water; W, body weight; BMC, bone mineral content; TBBM, total body bone mineral.

A three-compartment (3C) model consists of fat, fat-free solids, and water. The water content of FFM is assumed to be between 70% and 76% for most species and results from cross-sectional studies in adult humans show no evidence of differences in the hydration of FFM with age. The fat-free solids component of FFM refers to minerals (including bone) and proteins. The 3C approach involves the measurement of body density (usually by hydrodensitometry) and total body water by an isotope dilution technique. Assumptions are made that both the hydration of FFM and the solids portion of FFM are constant. Because bone mineral content is known to decrease with age, the 3C approach is limited in its accuracy in persons or populations where these assumptions are incorrect.

A four-compartment (4C) model involves the measurement of body density (for fat), total body water, bone mineral content by DXA, and residual (residual=body weight−(fat+water+bone)). This model allows for the assessment of several assumptions that are central to the 2C model. The 4C approach is frequently used as the criterion method against which new body composition methods are compared in both children and adults.

The more complex 4C model involves neutron activation methods for the measurement of total body nitrogen and total body calcium, where total body fat=body weight−total body protein (from total body nitrogen)+total body water (dilution volume)+total body ash (from total body calcium). A six-compartment model is calculated as follows: fat mass (measured from total body carbon)=body weight−(total body protein+total body water+bone mineral+soft tissue mineral (from a combination of total body potassium, total body nitrogen, total body chloride, total body calcium)+glycogen (total body nitrogen)+unmeasured residuals). However, the availability of neutron activation facilities is limited and therefore the latter models are not readily obtainable by most researchers.

At the organizational level, a five-level model was developed where the body can be characterized at five levels. The following are the levels and their constituents: atomic=oxygen, carbon, hydrogen, and other (level 1); molecular=water, lipid, protein, and other (level 2); cellular=cell mass, extracellular fluid, and extracellular solids (level 3); tissue-system level=skeletal muscle, adipose tissue, bone, blood, and other (level 4); whole body (level 5).

1.2.5 Body Volume and Body Density

The total BV is an indicator of body size, which is subsequently used to calculate body density (BD) (Eq. (1.22)):

(1.22) BD=BM×BV−1

and in consequence, body FM.

BV can be assessed by the water-displacement technique, also called “underwater weighting” or “hydrodensitometry,” or the air-displacement technique, also called “air-displacement plethysmography” (Duren et al., 2008). Both techniques are time-consuming, laborious and requires demanding laboratory conditions.

Hydrodensitometry is regarded as the most reliable of available techniques used to estimate BD. Archimedes’ principle is applied by comparing the mass of a subject in the air (Ma) with the “mass underwater” (Mw), which is calculated from the gravitational force (Fw) exerted on a submerged object according to the Newton’s law (Eq. (1.23)):

(1.23)Mw=Fw ×g−1

where g is gravitational acceleration of 9.81 m·s−2. During underwater measurement, total expiration is necessary and account is taken of the residual gas volume remaining in the lungs (Vr), and an estimated volume of gas in the intestine (Vi). Temperature, which influences water density (WD), should be also taken into account. BD is calculated with the following equation (Eq. (1.24), Brodie et al., 1998):

(1.24)BD=Ma ((Ma−Mw)/WD)−(Vr+Vi)

The volume of gas in the intestine (Vi) included in the calculation is usually assessed to amount to about 100 mL, but this value should be increased for large adults and decreased for children.

Underwater weighting (UWW)—considered to be the “golden standard” for BV measurements—is actually replaced by the DEXA method which does not require lung volume measurement for body fat determination.

BV can be estimated with classic formulae. In 1959, Sendroy and Cecchini (1959), developed a formula (Eqs. (1.25) and (1.26)) based on the data collected for 446 men and adolescent boys [the ratio of BM (kg) to height (cm) is between 0.2 and 0.8] as:

(1.25)BV(L)=BSA(m2 )×60.20×(BM/H)0.562

and for 113 adult women and adolescent girls (the ratio of BM to H is between 0.2 and 0.8) as:

(1.26) BV(L)=BSA(m2)×62.90×(BM/H)0.578

BSA and BV can be assessed on the basis of digital data recorded with the computer tomography, magnetic resonance imaging, or 3D scanning methods. The main advantage of these techniques is shorter time of acquisition, resulting in less measurement noise.

Introduction

In children and adolescents, the degree of body fat mass depends on ethnic background, gender, developmental stage, and age. Waist circumference, skinfold thickness, and body mass index are the most useful noninvasive clinical measures to define obesity. Waist circumference and waist-to-hip ratio are helpful to assess upper body fat deposition but do not provide for measuring visceral, or intra-abdominal, fat accumulation. Direct measurements of body fat content, e.g., hydrodensitometry, bioimpedance, or dual-energy X-ray absorptionmetry (DEXA), are useful tools only in scientific studies. Body mass index (BMI) (weight in kilograms divided by the square of the height in meters) is easy to calculate and is correlated sufficiently with direct measures of fatness. BMI is therefore frequently used to define obesity clinically. A child with a BMI above the 97th percentile with regard to age and gender is considered obese. A child with a BMI greater than the 90th percentile but below the 97th percentile would be considered overweight.

In adults, a BMI greater than 28 kg/m2 is associated with an increased risk of morbidity, such as stroke, ischemic heart disease, or type II diabetes mellitus. Adults with a BMI greater than 30 kg/m2 are classified as being obese (grade 2 overweight) and those with a BMI between 25 and 29.9 kg/m2 are considered to be grade 1 overweight. A BMI over 40 kg/m2 is classified as grade 3 overweight. A central distribution of body fat is associated with a higher risk of morbidity and mortality in adulthood. The International Obesity Task Force has proposed that the adult body mass index cut-off points (25 and 30 kg/m2) should be linked to body mass index percentiles for children to provide for child cutoff points.

1. Skinfold Thicknesses

This method involves the measurement of a fold of subcutaneous fat at one or more sites, which can then be interpreted using previously validated prediction equations into an estimate of fat mass. Probably the most widely used prediction equations are those developed by Durnin and Womersley (39) in which the sum of the skinfold thicknesses at one or more sites (up to four) is related to body density in healthy subjects measured by hydrodensitometry by age- and sex-specific equations of the form

density=A−B log10S,

where A and B are empirically derived coefficients and S is the sum of the skinfold measurements. Fat mass is then calculated using the equation of Siri (7) (see Section III,A) and measured body weight. The four sites used by Durnin and Womersly are biceps, triceps, subscapular, and suprailiac. The measurements are made using calipers, which exert a standardized pressure on the measurement site. With a single trained observer the method can yield very reproducible results. Systematic differences are found between skinfold measurements made by different operators on the same subjects. However, these are relatively small (40), although it is often stated that longitudinal studies are best carried out with a single operator. In view of the underlying uncertainty involved in extrapolating from skinfold thickness to body fat, the errors incurred from imprecision in locating the exact site for measurement are also relatively small (41). Accuracy of fat determination will be compromised if the subjects measured are not representative of the subjects whose data were used to establish the equations. Ethnic differences in fat patterning and changes in fat distribution due to disease will confound interpretation of results unless population-specific equations are used. We have shown that skinfold anthropometry is an inaccurate method of assessing total body fat in patients presenting for nutritional support in the surgical ward (42). Body fat was underestimated by about 3 kg in such patients when the reference method was a multicompartment model based on neutron activation and tritium dilution (43). Body fat may be overestimated in the presence of edema partly because of overestimation of the thickness of the skinfold and partly because of the increased body weight due to the excess fluid. In subjects, particularly the elderly, with flabby, easily compressible tissue, skinfold measurements may be difficult. In obese subjects reliable skinfold measurements may not be possible because the thicknesses may exceed the maximum jaw openings of the calipers (Harpenden, 60 mm; Holtain, 50 mm; Lange, 65 mm). Lee and Nieman (44) provide detailed instructions on carrying out the measurements at the various sites.

Methods

For a study to have been included in this chapter, all of the following criteria must have been satisfied: (1) randomized controlled trial; (2) primary endpoint of weight loss or change in body composition; (3) DCR or ICR as the primary intervention; (4) study duration of 8–30 weeks; (5) study population consisting entirely of adult, overweight or obese, nondiabetics; (6) publication date of year 2000 or later; and (7) total fat mass measured via dual-energy X-ray absorptiometry (DEXA), hydrodensitometry, air displacement plethysmography, computed tomography (CT), or magnetic resonance imaging (MRI). Due to the small number of ICR studies that met these inclusion criteria, the criteria were amended for this group to allow for the measurement of total fat mass via bioelectrical impedance analysis (BIA); this yielded three additional eligible studies [16–18]. Investigations including a cointervention that probably affected body composition (e.g. exercise) were included in this review only if the study featured a diet-only arm or were otherwise able to isolate the effects of the dietary intervention on visceral fat reduction.

On 1 February 2013, a PubMed search was conducted using the following input: (“calorie restriction” or “intermittent calorie restriction” or “alternate-day fasting” or “caloric restriction”) and (“body weight” or “weight loss” or “body composition”) and (“visceral fat” or “waist circumference”). Additional trials were identified using the references listed in these manuscripts. After applying the aforementioned inclusion criteria, this yielded 11 DCR studies (Table 17.1) and 5 ICR studies (Table 17.2) that were eligible for review. Investigations were grouped by trial duration and classified as short term (8–12 weeks) or moderate term (13–30 weeks).

Table 17.1. Daily Calorie Restriction: Effects on Body Weight and Body Composition

BMI, body mass index (in kg/m2); CR, calorie restriction; DLW, doubly labeled water; F, female; HC, high-carbohydrate; LC, low-carbohydrate; M, male; WC, waist circumference.

Table 17.2. Intermittent Calorie Restriction: Effects on Body Weight and Body Composition

BMI, body mass index (in kg/m2); CR, calorie restriction, F, female; HF, high-fat; LF, low-fat; M, male; WC, waist circumference.

We used two separate methodologies for estimating dietary adherence. First, we defined percentage adherence as (percent energy restriction achieved/percent energy restriction prescribed) × 100. We allowed for values >100%, as this would indicate that a weight loss diet was so effective that participants reduced energy intake even more than the prescribed reduction (which, in an overweight and obese population, should be viewed positively). A limitation of this approach is that most of the data pertaining to the percentage energy restriction achieved was derived from food records, which tend to underestimate food intake (especially in an overweight and obese population) [19]. We therefore used percentage change in total fat mass as a second indicator of dietary adherence. For this analysis, a diet regimen was regarded as having greater adherence if it reduced total fat by ≥2.0% more (absolute difference) than its competitor.

Each of the ICR trials used waist circumference as an estimate for visceral fat, and none of them measured subcutaneous fat. Consequently, while it would have been preferable to compare the ratio of visceral fat reduction to subcutaneous fat reduction between DCR and ICR studies, instead we compared the ratio of waist circumference reduction to total fat mass reduction.