Body adiposity index (BAI) correlates with BMI and body fat pre- and post-bariatric surgery but is not an adequate substitute for BMI in severely obese women.

OBJECTIVE: Body Adiposity Index (BAI), a new surrogate measure of body fat (hip circumference/[height 1.5-18]), has been proposed as a more accurate alternative to BMI. We compared BAI with BMI and their correlations with measures of body fat, waist circumference (WC), and indirect indices of fat pre- and post-Roux-en-Y gastric bypass (RYGB). METHODS: Sixteen clinically severe obese (CSO) non-diabetic women (age = 33.9± 7.9 SD; BMI = 46.5±9.5 kg/m(2)) were assessed pre-surgery, and at 2 (n=9) and 5 mo (n=8) post-surgery. Body fat percentage (% fat) was estimated with bioimpedance analysis (BIA), air displacement plethysmography (ADP), and dual-energy x-ray absorptiometry (DXA). WC, an indicator of central fat, and both plasma leptin (ng/ml) and insulin (mU/l) concentrations were measured as indirect body fat indices. Pre- and post-surgery values were analyzed with Pearson correlations and linear regressions. RESULTS: BAI and BMI correlated significantly with each other pre-surgery and at each time point post surgery. BAI and BMI also correlated significantly with % fat from BIA and ADP; however, only BMI correlated significantly with % fat from DXA pre- and post-RYGB. BMI was the single best predictor of WC and leptin at 2 and 5 mo post-surgery and had significant longitudinal changes correlating with % fat from BIA and DXA as well as with leptin. DISCUSSION: Both BAI and BMI were good surrogates of % fat as estimated from BIA and ADP, but only BMI was a good surrogate of % fat from DXA in CSO women. Thus, BAI may not be a better alternative to BMI.

Night eating status and influence on body weight, body image, hunger, and cortisol pre- and post- Roux-en-Y Gastric Bypass (RYGB) surgery.

Night Eating Syndrome is a common disorder in severely obese individuals and may be associated with hypothalamic pituitary adrenal (HPA) axis dysregulation. This study compared night eaters (NE) and comparably obese controls (C) pre- and post-Roux-en- Y Gastric Bypass surgery at 2 and 5 months, following an overnight fast on hormonal measures associated with HPA axis and related appetite and psychological measures. There were 24 (10 NE, 14 C) clinically severely obese participants (body mass index =47.0+/-8.4 SD). At pre-surgery baseline, afternoon fasting hunger ratings differed significantly and were lower for NE than for C (p=0.01). Eight of the participants (4 NE, 4C) returned for all 3 study visits. At 5 months post-surgery, NE and C did not differ in weight loss, reductions in waist circumference, insulin levels, and insulin resistance (homeostasis model assessment). However, NE as compared to C, did not improve in self ratings of body image (p<0.05), and had significant increases in fasting afternoon cortisol levels 5 months after surgery (p=0.01).

Nourishing the obese patient.

Obese patients are frequently encountered in hospitals. This is not unexpected given the fact that obesity currently constitutes a worldwide public health epidemic. The clinical indications for nutritional support and route of nutrition support selected should be similar in obese and normal weight patients. Determining nutritional requirements by conventional methods and formulas are often inaccurate in this population. For this reason, direct measurement of energy needs using indirect calorimetry when available has become the preferred method. A strategy employing hypocaloric nutrition support will be presented and discussed.

Insurance decisions about obesity surgery: a new type of randomization?

BACKGROUND: Studies of obesity surgery are frequently criticized for lack of an appropriate non-operative control arm. Additionally, insurance approval for coverage of these procedures can be difficult to obtain by patients and caregivers. This retrospective study tested the hypothesis that the insurance preapproval process would yield well-matched operative and non-operative treatment groups which could simulate a randomization process. METHODS: Of 466 patients deemed to be appropriate candidates for surgery, 58% ultimately received surgical therapy. Roux-en-Y gastric bypass (RYGBP) was performed on 244 patients who were compared with 187 patients who did not undergo surgery (NonOP). RESULTS: The groups were similar in gender (81% female), age (39 yr), and Body Mass Index (52 kg/m2). The percentage of African Americans in the NonOP group was greater. The distribution of comorbid conditions among the groups were similar. CONCLUSIONS: The insurance approval process results in a reasonable control group for parameters except race.

Survival of critically ill surgical patients discharged to extended care facilities.

BACKGROUND: Rates of discharge of surgical ICU (SICU) patients to extended care facilities (ECF) increase as SICU length of stay (LOS) increases. Increased SICU LOS and APACHE II scores have been related to increased hospital mortality. This study evaluated factors influencing ECF survival after SICU patient discharge. STUDY DESIGN: We did a longitudinal followup study of patients admitted to our tertiary care SICU during a 2-year period who were eventually discharged to ECF Demographic data, SICU admission APACHE II score, and LOS data were obtained prospectively. Patient followup was obtained 2 years after discharge by telephone interviews with patients themselves or next of kin to ascertain current status or date of demise. RESULTS: Of 1,799 SICU patients admitted during the study period, 160 patients (9%) were discharged to an ECF Telephone followup was obtained from 150 patients (94%). Mean length of followup was 21 months after hospital discharge (range 7 to 34 months), mean patient age 64 years (range 16 to 96 years), mean SICU admission APACHE II score 13 (range 2 to 29), and mean SICU LOS 11 days (range 1 to 146 days). At followup, 45% of patients had died, 37% had been discharged home, and 18% still resided in an ECF or hospital. Elderly patients (above age 65) had significantly worse 1-year (p < 0.001) and 2-year (p < 0.001) ECF survival than nonelderly patients. Patients admitted to the SICU after otolaryngologic procedures also had significantly worse 1- and 2-year ECF survival than all other patients. Severity of illness as estimated by admission APACHE II scores or SICU LOS does not seem to influence survival. CONCLUSIONS: Outcomes of ECF discharge after SICU admission is poor, with nearly 50% 2-year mortality. ECF mortality seems significantly higher for the elderly, with patients undergoing otolaryngologic procedures being at highest risk. Severity of illness at the time of SICU admission and SICU LOS does not seem to influence ECF outcomes.

A health status assessment of the impact of weight loss following Roux-en-Y gastric bypass for clinically severe obesity.

BACKGROUND: The field of "medical outcomes" emphasizes effects of medical treatments on quality of life as seen from the patient's perspective. The increasing incidence of obesity has had tremendous impact on the physical, psychological, social, and economic health of our nation with important longterm implications for the development of future social and health care policies. This study evaluated the effects of clinically severe obesity on overall health status measured in a standardized fashion and the impact of durable weight loss achieved through surgical intervention. STUDY DESIGN: Patients scheduled for Roux-en-Y gastric bypass for treatment of obesity were prospectively evaluated. At the preoperative visit, each patient completed Short Form 36 (SF-36). Postoperatively, patients were again asked to complete SF-36, in person or through a telephone interview at an interim point (3 to 12 months) and after their weight had reached a plateau (>18 months). RESULTS: The mean body mass index (BMI) was 51+/-10 kg/m2 preoperatively (range 38 to 85 kg/m2). Mean BMI was 45+/-10 kg/m2 (range 33 to 78 kg/m2) at the interim point and 35+/-8 kg/m2 (range 28 to 55 kg/m2) at plateau. The weight change for the group was from 306+/-8 lb (138+/-4 kg) preoperatively to 211+/-55 lb (96+/-25 kg) at the plateau, with the average percent of excess body weight lost being 63+/-23% at the plateau. Preoperatively, patients with clinically severe obesity scored significantly lower than the normal population in all areas except Role Activities (Emotional Factors). At the plateau period, patients demonstrated significant improvement in limitations in all areas compared with preoperative values and scores were the same as (Physical Activities, Role Activities [Physical Factors], General Mental Health, General Health Perceptions), or significantly better than (Social Functioning, Role Activities [Emotional Factors], Bodily Pain, Vitality), the national "normal" population. CONCLUSION: Clinically severe obesity is a chronic disabling disease that results in significantly decreased health status in seven of the eight areas measured by SF-36. This disability resolves with successful weight reduction. In some areas, function even surpasses the national "normal" population. Surgical treatment of clinically severe obesity has a profoundly positive impact on patients' perception of their health status.

Comparison of indirect calorimetry, the Fick method, and prediction equations in estimating the energy requirements of critically ill patients.

BACKGROUND: Accurate measurement of resting energy expenditure (REE) is helpful in determining the energy needs of critically ill patients requiring nutritional support. Currently, the most accurate clinical tool used to measure REE is indirect calorimetry, which is expensive, requires trained personnel, and has significant error at higher inspired oxygen concentrations. OBJECTIVE: The purpose of this study was to compare REE measured by indirect calorimetry with REE calculated by using the Fick method and prediction equations by Harris-Benedict, Ireton-Jones, Fusco, and Frankenfield. DESIGN: REEs of 36 patients [12 men and 24 women, mean age 58+/-22 y and mean Acute Physiology and Chronic Health Evaluation II score 22+/-8] in a hospital intensive care unit and receiving mechanical ventilation and total parenteral nutrition (TPN) were measured for > or = 15 min by using indirect calorimetry and compared with REEs calculated from a mean of 2 sets of hemodynamic measurements taken during the metabolic testing period with an oximetric pulmonary artery catheter. RESULTS: Mean REE by indirect calorimetry was 8381+/-1940 kJ/d and correlated poorly with the other methods tested (r = 0.057-0.154). This correlation did not improve after adjusting for changes in respiratory quotient (r2 = 0.28). CONCLUSIONS: These data do not support previous findings showing a strong correlation between REE determined by the Fick method and other prediction equations and indirect calorimetry. In critically ill patients receiving TPN, indirect calorimetry, if available, remains the most appropriate clinical tool for accurate measurement of REE.

Cellular immunotherapy of advanced human immunodeficiency virus type 1 infection using autologous lymph node lymphocytes: effects on chemokine production.

A pilot study was undertaken in patients with human immunodeficiency virus type 1 (HIV-1) infection to examine the effects of infusing autologous lymph node lymphocytes that had been cultured ex vivo in conditions designed to maximize the specific secretion of HIV-1-suppressive factors, including beta chemokines. Ten patients with CD4 cell counts between 119 and 436/microliter on antiretroviral drugs received a single infusion of CD4 and CD8 lymph node lymphocytes. There were no serious acute or chronic adverse clinical effects. Increases in serum levels of macrophage inflammatory protein 1beta (MIP-1beta) and increases in the production of MIP-1beta by peripheral blood lymphocytes in response to HIV-1 env were observed. Increases in CD4 and CD8 cell counts and skin test reactivity to recall antigens and decreases in HIV-1 virus load were also observed. This cellular immunotherapy can modulate beta chemokine production in patients with advanced HIV-1 infection and may contribute immunorestorative and antiviral activities.

Mechanisms of weight loss after surgery for clinically severe obesity.

Surgical treatment of clinically severe obesity is becoming more established within the medical and lay communities, with a variety of procedures currently being performed. Little has been published concerning and comparing the metabolic effects produced by these procedures and the mechanisms by which they produce weight loss. This article reviews the physiology of weight loss induced by semi-starvation and other proposed mechanisms of surgically induced weight loss.

Changes in measured resting energy expenditure after Roux-en-Y gastric bypass for clinically severe obesity are not related to bypass limb-length.

BACKGROUND: Roux-en-Y gastric bypass (RYGB) for clinically severe obesity (CSO) results in a 'paradoxical' response of the measured resting energy expenditure (MREE) in which the MREE remains within the predicted range based upon the Harris-Benedict (HB) equation, despite a significant decrease in caloric intake to 500-1000 kcal/day. The mechanism for this response is unknown. A study was undertaken to determine whether the changes in MREE after RYGB are related to limb-length of the gastric bypass. METHODS: A prospective clinical trial of varying limb-lengths based on body mass index (BMI) in patients having RYGB for CSO. The records of patients who underwent RYGB for CSO and had MREE measured at baseline, 6 months and 12 months postoperation were reviewed. MREE was performed using a Med Graphics CCM system after an overnight fast or at least 4 hours after a light meal, and a 30 minute rest in a supine position in a neutral environment, on the same day of the week between the hours of 10 a.m. and 4 p.m. Patients were selected for RYGB in accordance with NIH recommendations. RYGB was performed in a standardized fashion with the Roux limb-length varied as follows: (A) BMI < or = 51 kg/m2 - 75 cm limb (n = 20); (B) BMI < or = 51 kg/m2 - 150 cm limb (n = 16); (C) BMI > or = 51 kg/m2 - 150 cm limb (n = 18); or (D) BMI > or = 51 kg/m2 - 250 cm limb (n = 6). RESULTS: Data from 60 patients (nine male, 51 female; mean age 39 years; mean baseline BMI 51.5 +/- 10 kg/m2; mean baseline weight 145 +/- 32 kg) were analyzed. There were no significant differences in MREE or percentage HB-predicted energy expenditure between the groups. CONCLUSIONS: These data suggest that the observed changes in MREE following RYGB for CSO are not related to the limb-length of the bypass.

Effects of low-dose dopamine on urine output in oliguric, critically ill, renal transplant patients.

UNLABELLED: Low-dose dopamine (LD-DA) has been used extensively to increase urine output (UO) in critically ill patients. These effects have recently been documented in patients with normal and mildly abnormal renal function. The purpose of this study was to quantitate the effects of LD-DA on UO and urineNa (UNa) excretion in renal transplant (RT) patients, and thereby evaluate the effects of LD-DA on the denervated kidney. METHODS: Five RT patients and 7 non-transplant controls, hospitalized in the surgical intensive care unit (SICU), with serum creatinine (serum Cr) < 2 mg/dL who were oliguric (UO < 0.5 mL/kg/h), received LD-DA (2.5 micrograms/kg/min). None received other diuretics within 12 h, and all had pulmonary artery occlusion pressure (PAOP) > 10 mmHg and CI > 3.0 L/min/m2. UO was measured hourly and averaged for 2 h pre and 6 h during LD-DA. All data are mean +/- SD. RESULTS: APACHE II (14 +/- 4), CI (4.1 +/- 1.2 L/min/m2), PAOP (15 +/- 4 mmHg), HR (98 +/- 16/min), and MAP (83 +/- 10 mmHg) were similar between groups and did not change during LD-DA therapy. Initial serum Cr in the RT group (1.6 +/- 0.4 mg/dL) was greater than that in controls (0.9 +/- 0.24 mg/dL), p < 0.05. Initial UO [0.26 +/- 0.10 mL/kg/h (RT) and 0.31 +/- 0.12 mL/kg/h (controls)] and initial UNa [8 +/- 62 meq/L (RT) and 54 +/- 28 meq/L (controls)] were not different. Urine output increased significantly compared with baseline in both groups [final UO 0.55 +/- 0.14 mL/kg/h (RT) and 0.96 +/- 0.41 mL/kg/h (controls)]. Final UNa [72 +/- 37 meq/L (RT) and 99 +/- 56 meq/L (controls)] were not different from each other or from baseline. CONCLUSIONS: LD-DA increases UO, but not UNa excretion, in RT patients with oliguria, comparably to controls. These data suggest that this effect is predominantly mediated by dopaminergic receptors, since the transplanted kidney is denervated and there were no significant associated changes in hemodynamic parameters during the study.

Acute acalculous cholecystitis: incidence, risk factors, diagnosis, and outcome.

The objective of this study was to review the incidence, risk factors, methods of diagnosis, and outcome of acute acalculous cholecystitis (AAC) and to identify the sensitivity and limitations of current radiographic modalities used to establish the diagnosis. Our study was a retrospective chart review in a tertiary-care university hospital. Over a 53-month period, 27 cases of AAC (17 males, 10 females; mean age 50 years; mean Acute Physiology and Chronic Health Evaluation II score, 17) were encountered. Of these, 14 (52%) occurred in critically ill patients and 17 (63%) in patients recovering from non-biliary tract operations. AAC occurred in 0.19 per cent of surgical intensive care unit admissions and accounted for 14 per cent (27 of 188) of all cases of acute cholecystitis. Presenting symptoms and laboratory values were nonspecific. Twenty patients had radiographic studies before surgery. Among the various radiological studies used for AAC, morphine cholescintigraphy had the highest sensitivity (9 of 10; 90%), followed by computed tomography (8 of 12; 67%) and ultrasonography (2 of 7; 29%). Ten of the 20 patients had more than one study done preoperatively. All 27 patients had an open cholecystectomy. AAC was associated with a high incidence of gangrene (17 of 27 cases; 63%), perforation (4 of 27; 15%), and abscess (1 of 27; 4%). The mortality rate was 41 per cent (11 of 27). We conclude that AAC is a rare, but potentially lethal, disease occurring in critically ill patients and those recovering from non-biliary tract operations. The clinical presentation is nonspecific, and significant delays in diagnosis result in a high incidence of gangrene, perforation, abscess, and death. To improve outcome, a high index of suspicion with early radiographic evaluation, often employing multiple studies, is necessary. An algorithm for the evaluation of patients for suspected AAC is proposed.

Surgical implications of obesity.

Obesity is perhaps the most significant public health problem facing the United States today. Obese patients are at increased risk for numerous medical problems, which can adversely affect surgical outcome. However, these risks have not uniformly translated into increased or prohibitive operative morbidity and mortality in this population. With appropriate perioperative precautions and monitoring, the incidence of serious cardiovascular and pulmonary complications can be minimized. Obese patients can be treated as safely and effectively as their normal weight counterparts under most circumstances and should not be denied surgical treatment for any disorder when surgery constitutes the most appropriate therapy. When indicated, surgical treatment should be considered for patients with clinically severe obesity, since currently it appears to offer the best long-term results for weight control and amelioration of comorbidity.

Preoperative intensive care unit admission and hemodynamic monitoring in patients scheduled for major elective noncardiac surgery: a retrospective review of 95 patients.

OBJECTIVE: To review experience with preoperative intensive care unit (ICU) admission and hemodynamic monitoring to determine which patients benefited and how. DESIGN: Retrospective review over 32-month period (1991 to 1994). SETTING: Surgical ICU of a university teaching hospital. PARTICIPANTS: Ninety-five patients admitted to the surgical ICU before a major elective noncardiac, nonthoracic surgical procedure. INTERVENTIONS: All patients underwent hemodynamic monitoring with a pulmonary artery catheter (PAC). Interventions were made at the discretion of the ICU attending and attending surgeon, based on a general algorithm. Patients were categorized based on history or hemodynamics. The historic classification was as follows: group I, patients with cardiac disease documented by history and cardiac imaging, n = 37; group II, patients with cardiac disease documented by history, but not cardiac imaging, n = 24; group III, patients without documented cardiac disease, but with other significant medical problems, n = 34. Hemodynamic classification considered patients to have subnormal parameters if the cardiac index was < 2.5 L/min/m2, the mixed venous oxygen saturation was < 65%, or the oxygen delivery index was < 350 mL/min/m2 (n = 45), and normal parameters if greater than these (n = 50). MAIN RESULTS: There were no differences in APACHE II scores. Group I patients had greater Goldman Cardiac Risk Indices than group III patients (7.4 +/- 4.8 v 5.0 +/- 3.0). Patients in group I had a significantly greater incidence of subnormal initial hemodynamic values (63%) than patients in group II (47%) or group III (32%). The incidence of postoperative cardiovascular complications among groups was not different. Fifty patients (52%) had normal hemodynamics initially; two (4%) developed postoperative cardiovascular complications compared with 10 patients (22%) of the 45 with subnormal initial hemodynamic values. Of these 45 patients, 24 (52%) had their hemodynamic parameters corrected preoperatively with crystalloids, packed red blood cells, inotropes, and/or afterload reduction. Two of these 24 patients (8%) experienced postoperative cardiovascular complications, compared with 8 of the remaining 21 patients who had no attempt to normalize their hemodynamic values preoperatively other than maintaining a normal pulmonary artery occlusion pressure. CONCLUSIONS: Patients who had normal initial preoperative hemodynamic parameters or abnormal initial parameters that were normalized preoperatively experienced significantly fewer perioperative cardiovascular complications than those with abnormal initial values that were not normalized preoperatively. These results suggest that there may be benefit to the practice of preoperative ICU admission, hemodynamic monitoring with a PAC, and "optimization" of cardiac function in selected patients undergoing major elective noncardiac surgery. Further studies are needed to better delineate the most appropriate patient populations and effective therapeutic protocol.

Changes in measured resting energy expenditure after Roux-en-Y gastric bypass for clinically severe obesity.

BACKGROUND: Roux-en-Y gastric bypass (RYGB) results in sustained weight loss and amelioration of comorbid conditions in patients with clinically severe obesity. The mechanism of weight loss after RYGB is not well defined. The objective of this study was to document the changes in measured resting energy expenditure (MREE) over time in patients with clinically severe obesity after RYGB. METHODS: We prospectively studied MREE in 70 patients (11 male, 59 female; body mass index [BMI], 40 to 80 kg/m2) treated by RYGB. MREE was measured by indirect calorimetry before operation and at 6 weeks and 3, 6, 12, 18, and 24 months after operation. Patients were stratified to hypometabolic ([HM] MREE less than 85% of Harris-Benedict [HB] predicted; n = 22) or normal metabolic rate ([NM] MREE +/- 15% HB predicted; n = 48) before operation; mean BMIs were HM, 53.4 +/- 11.0 kg/m2; NM, 51.4 +/- 9.8 kg/m2; p = not significant. MREE, weight loss, percent excess body weight loss (EWL), and energy intake were determined at each time point. RESULTS: Overall, MREE was significantly less than HB-predicted REE before operation (90 +/- 28%), but rose to become equal to the HB-predicted REE by 6 weeks (96 +/- 15%) and remained so. When stratified by initial metabolic rate, MREE increased significantly in the HM patients by 6 weeks, from 1329 +/- 604 kcal/day (55% of HB predicted) to 1882 +/- 398 kcal/day (88% of HB predicted) (p < 0.001), and MREE remained normal (2332 +/- 484 kcal/day to 2029 +/- 410 kcal/day) in the NM patients. Percent EWL was similar in both groups at each time. Energy intake was 2603 +/- 982 kcal/day before operation and fell to 815 +/- 196 kcal/day at 3 months, 969 +/- 241 kcal/day at 6 months, 1095 +/- 307 kcal/day at 12 months, 1259 +/- 466 kcal/day at 18 months, and 1373 +/- 620 kcal/day at 24 months, and was similar between the groups at each time point. Percent HB-predicted REE increased significantly after operation despite a significant decrease in energy intake. CONCLUSIONS: RYGB is associated with significant changes in MREE over time. In NM patients MREE fell over time consistent with weight loss but remained normal, whereas patients who were hypometabolic exhibited increases in MREE toward normal. These changes in MREE occurred despite reduced energy intake comparable to a very low calorie diet. This paradoxical effect on MREE may contribute to the enhanced weight loss associated with RYGB.

A prospective randomized trial of preoperative "optimization" of cardiac function in patients undergoing elective peripheral vascular surgery.

BACKGROUND: Previous investigations have suggested that preoperative invasive hemodynamic monitoring with "optimization" of cardiovascular function may favorably affect the outcome among patients undergoing peripheral vascular surgery. The purpose of this study was to evaluate the effect of preoperative optimization of hemodynamic parameters on outcome in patients undergoing aortic reconstruction (AR) or limb salvage procedures (LSP) in a randomized, prospective clinical trial. METHODS: All 72 patients who consented to participate in this study were admitted to the intensive care unit at least 12 hours before operation for placement of a pulmonary artery catheter (PAC). Patients who were randomized to the treatment group (n = 32) were "optimized" by adjusting their hemoglobin concentration, oxygen saturation (SaO2), cardiac output, or afterload until the mixed venous O2 saturation (SvO2) was at least 65%. The control group (n = 40) underwent placement of a PAC and had oxygen transport parameters measured without any attempt to optimize SvO2. RESULTS: There were no significant differences between the treatment and control groups with respect to age, gender, type of operation, initial Acute Physiology and Chronic Health Evaluation (APACHE) II score, SvO2, pulmonary artery occlusion pressure, or cardiac index. All treatment patients achieved an SvO2 of at least 65% before operation. Comparing the treatment and control groups, postoperative cardiovascular complications occurred in 25% versus 27%, intraoperative complications in 28% versus 20%, and death in 9% versus 5%, respectively. None of these differences was statistically significant as a whole or within the subgroups undergoing AR or LSP. CONCLUSIONS: These data suggest that preoperative optimization of cardiovascular function by using achievement of SvO2 above 65% as the end point does not result in any reduction of intraoperative or perioperative cardiac complications in patients undergoing PVS. Further studies with alternative assessments and manipulation of different cardiopulmonary parameters may yield additional information.

Hypoenergetic nutrition support in hospitalized obese patients: a simplified method for clinical application.

Nutrition support in obese hospitalized patients is controversial, with some practitioners advocating restricted energy or hypoenergetic feedings when patients are being actively treated for another disease. To eliminate the need for indirect calorimetry, this randomized, double-blind, prospective study was undertaken to determine whether obese hospitalized patients given a hypoenergetic parenteral regimen administered to provide 2 g protein x kg ideal body wt (IBW)(-1) x d(-1), could achieve nitrogen balance comparable with that of control subjects given isonitrogenous normoenergetic formula. Thirty obese hospitalized patients with an average body mass index (BMI; in kg/m2) of 35 were randomly assigned to the hypoenergetic [energy (kJ):nitrogen (g) = 314:1; energy (kcal):nitrogen (g) = 75:1; n = 16] or control [energy (kJ):nitrogen (g) = 628:1; energy (kcal):nitrogen (g) = 150:1; n = 14] formulas. The initial formula volume administered provided 2 g protein x kg IBW(-1) x d(-1). Nitrogen balance was determined on day 0 and weekly. The total daily energy intake [per kg actual body weight (ABW)] was 57 +/- 12 kJ (hypoenergetic) compared with 94 +/- 21 kJ (control), P < 0.001, and the nonprotein energy intake was 36 +/- 10 kJ (hypoenergetic) compared with 73 +/- 17 kJ (control), P < 0.001. Protein intake was the same per ABW, 2.0 +/- 0.2 and 2.0 +/- 0.1 g kg IBW(-1) x d(-1), NS, for the hypoenergetic and control formulas, respectively. Mean net nitrogen balance was not significantly different between the groups, even after patients were subgrouped by illness, nor was the percentage of patients achieving positive nitrogen balance. Duration of treatment averaged 10.5 +/- 2.6 d. Weight change did not differ significantly between groups. These data indicate that patients receiving hypoenergetic feedings providing 2 g protein x kg IBW(-1) x d(-1) achieved nitrogen balance comparable with patients given conventional total parenteral nutrition regimens, even when critically ill.