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The medical profession is facing the challenges of the 1990s with a shift to outpatient care and preventive services. Medical schools will need to respond to these forces by reevaluating their curricula and setting new objectives. Nutrition is an essential element in the process of curriculum change. The nutrition educator will be expected to take a leading role in integrating nutrition into the medical school curriculum. This report presents steps and strategies to initiate the process.

Total body water (TBW) measured by bioelectrical impedance analysis (BIA) was directly compared with deuterium-isotope dilution in a total of 58 subjects. First, sex-specific and group equations were developed by multiple regression analysis in (10 each) obese and nonobese men and women. Height/resistive impedance was the most significant variable used to predict deuterium-dilution space (D2O-TBW) and, combined with weight, yielded R = 0.99 and SE of estimate = 1.75 L. Equations predicted D2O-TBW equally well for obese and nonobese subjects. Second, the equations were prospectively tested in a heterogeneous group of 6 males and 12 females. Sex-specific equations predicted D2O-TBW with good correlation coefficients (0.96 and 0.93), total error (2.34 and 2.89 L), and a small difference between mean predicted and measured D2O-TBW (-1.4 +/- 2.05 and -0.48 +/- 2.83 L). BIA predicts D2O-TBW more accurately than weight, height, and/or age. A larger population is required to validate the applicability of our equations.

Estimation of lean body mass (LBM) is an important procedure in nutritional assessment and the availability of a rapid, portable and reproducible method would be desirable for this purpose. At present, only bioelectrical impedance analysis (BIA) and skinfold anthropometry are applicable for clinical use. We compared the prediction of LBM by these two methods in 80 subjects stratified into four subgroups by body mass index (BMI): lean, normal, obese and super-obese. Highly significant correlation coefficients (r greater than 0.92, P less than 0.001) were seen for all subgroups with a mean difference between techniques LBManthro-LBMBIA/LBManthro X 100) of less than 1 kg or 1 per cent error. A greater s.d. and error was noted in the super-obese (BMI greater than or equal to 40.0). Fifteen subjects had measurements repeated after a mean weight loss of 10 per cent. Although mean difference between methods was not statistically significant, there was a large individual variation. It is concluded that there is an excellent agreement between the estimation of LBM by bioelectrical impedance and skinfold anthropometry in the weight-stable subject.

The doubly labeled water method was compared with intake-balance for measuring energy expenditure in five patients receiving total parenteral nutrition (TPN). Because parenteral solutions were isotopically different from local water, patients had to be placed on TPN at least 10 days before the metabolic period. Approximately 0.1 g 2H2O and 0.25 g H2(18)O per kg total body water were given orally. We collected saliva before, 3 h, and 4 h after the dose for measurement of total body water and urine before, 1 day, and 14 days after the dose for measurement of isotope eliminations. On day 14, total body weight was remeasured and change in body energy stores was calculated, assuming constant hydration. Intake was assessed from weights of TPN fluids plus dietary record for any oral intake. Energy expenditure from doubly labeled water (+/- SD) averaged 3 +/- 6% greater than intake-balance. Doubly labeled water method is a noninvasive, nonrestrictive method for measuring energy expenditure in patients receiving TPN.

For the purposes of determining body composition, the body can be viewed as the sum of two components, fat and fat-free mass, the latter including water, protein, and minerals. Current methods for determining the size of these various components of the body are either inexact, invasive, or dependent on expensive or slow instrumentation. Bioelectrical impedance, which is rapid, noninvasive, and relatively inexpensive is examined as an alternative method for measuring body composition. The potential for the impedance technique arises from the very different electrical properties of the body components. The theory of bioelectrical impedance analysis is briefly presented, and human applications are discussed. The results of studies validating the method are cited.