The surgical treatment of morbid obesity

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.

Obesity: basic considerations and clinical approaches

Obesity, defined as an excess of body fat, can be measured with a variety of techniques, but in most epidemiologic studies it is estimated from height and weight or from skinfold thickness. The "gold standard" for body fat is the body density from which fat and fat-free body mass can be calculated. The new technique of bioelectric impedance analysis may substantially improve the estimation of total body fat. For estimating regional fat distribution, either waist to hip circumference ratio or subscapular skinfold have been most useful. Using the body mass index, defined as weight in kilograms divided by the square of the height in meters (kilogram per square meter), the National Health and Nutrition Examination Survey estimated that 26%, or 34 million, adult Americans aged 20 to 75 were overweight. The prevalence of severe overweight (a body mass index above 30 kg/m2) is higher in the United States and Canada than in Great Britain, the Netherlands, or Australia. Obesity results from an increase in energy intake relative to expenditure. Total daily energy expenditure includes energy used during resting metabolism, energy associated with the ingestion of food, and energy needed for physical activity. The obese are often observed to be less active, but since carrying a heavier load requires more energy, their total energy expenditure may not be low. A low resting metabolic rate has been suggested as a predictor of future risk of becoming obese. Adipose tissue is the major site for fat storage and may contain more than 90% of total energy stores. The increase in body mass index or degree of body weight is associated with an increased risk of heart disease, hypertension, gall bladder disease, and diabetes mellitus. When fat is centrally located in either males or females, the risk for these diseases is also increased, and may be a more important risk factor than total overweight itself. Genetic factors form the background from which obesity develops. The best estimates suggest that these genetic factors may be of less importance than environmental events in determination of total body fat and its distribution. Obesity can be classified on the basis of the total number of fat cells and regional fat distribution by using the etiological factors which caused the obesity or by determining the age at which the obesity began. Regardless of the cause, treatment for obesity should be based on an evaluation of the individual's risk from obesity as compared with the risk of the treatment under consideration. (ABSTRACT TRUNCATED AT 400 WORDS)

Surgery for morbid obesity: the patients' experiences

A survey of 123 adult patients who had undergone surgery for the treatment of morbid obesity was conducted to obtain data on patients' perceptions of preparation for surgery, care received during hospitalization, postoperative physical changes, changes in food tolerance, self-concept before and after surgery, work experience before and after surgery, and the relative importance of various forms of follow-up care. The study has implications for nursing practice in early diagnosis of patient problems, improved anticipatory teaching, and better training of health care professionals to assist the morbidly obese patient. The tolerable and nontolerable food lists generated from the data represent a significant contribution to patient care.

Long-term morbidity and mortality in morbidly obese adolescents after jejunoileal bypass

To evaluate the long-term results of jejunoileal bypass in the treatment of morbidly obese adolescents, we studied 11 patients who underwent surgery between 1972 and 1974. More than 10 years after surgery, 45% of the patients had extremely satisfactory results (correction of morbid obesity). Three patients died within the year after surgery, two of them under extenuating clinical circumstances. There have been no subsequent deaths. All eight survivors were found to have metabolic abnormalities to various degrees. Two patients had a total of five pregnancies; each had one healthy infant, and three pregnancies ended in abortion (one spontaneous). Two patients had significant medical problems related to the procedure but basically remained in good health, whereas three patients had severe symptoms requiring reanastomosis. Of the five patients who continue with the bypass, none has become significantly obese. They have all maintained a weight loss of between 45 and 90 kg, and as adults express strong feelings in favor of the procedure. This series demonstrates that, although significant weight loss was maintained, and improvement in the quality of life for half of our patients was dramatic, side effects and complications continue to develop, mandating careful follow-up for an indefinite time.

Complications of gastric restrictive operations in morbidly obese patients

After gastric restrictive procedures in morbidly obese persons, the reported morbidity is 15 per cent, and mortality is 1 per cent. Pulmonary embolism continues to be the most serious complication. Gastric perforations must be recognized early and treated promptly, as must the common postoperative complications: pneumonia, atelectasis, and wound infection.