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Biomedical subjects

S N Kreitzman

Publications and source records attributed to S N Kreitzman.

At least 19 recordsLinked to original sources
PubMed1992

Factors influencing body composition during very-low-calorie diets.

Apparent body composition changes with weight loss on very-low-calorie diet (VLCD) can depend on the method of fat-free mass estimation. In this report the implications of differences in measurement by direct versus indirect methods are examined. The nitrogen sparing and protein economy associated with ketosis is relevant and results of clinical trials with diets of varying composition are presented. The analytical findings of a multicenter, multimethod long-term VLCD study illustrate protein and metabolic conservation during VLCD. Protein losses, by total body nitrogen, over 10 wk dieting, independent of body mass index, were 4.75% of weight lost, as conservatively expected from obesity tissue reduction with no degradation of total energy expenditure. The implications of utilization of glycogen (water and potassium release) in interpretation of diet success and of body compositional change is evaluated. Evidence is presented that ultimate compositional changes with weight change may be individually specific and that body composition may be predicted from weight considerations alone.

Adipose Tissue↗
PubMed1992

Dependence of weight loss during very-low-calorie diets on total energy expenditure rather than on resting metabolic rate, which is associated with fat-free mass.

The assumption that total energy expended is related to resting metabolic rate (RMR) has not been validated. Intuitively, weight lost should be determined by the difference between the total energy consumed and the total energy expended. The ratio of actual daily energy usage to RMR by subjects dieting for 11 wk on a 1695-kJ (405-kcal) very-low-calorie diet (VLCD) was variable 1.9 +/- 0.3 (range 1.47-2.36). Weight loss correlated with total energy expenditure measured by 2H2 18O and not RMR, body mass index or body composition. Although RMR may be a reliable indicator of fat-free mass, there is little evidence that subjects with similar RMR will lose comparable weight or have comparable difficulty in weight maintenance.

Adult↗
PubMed1992

Changes in total body nitrogen during weight reduction by very-low-calorie diets.

Body composition measurements, including total body nitrogen (TBN) by in vivo neutron activation analysis, were made on 11 female volunteers before and after an 11-wk very-low-calorie diet (VLCD) [1695 kJ (405 kcal) 6.7 g N]. Mean body mass index (BMI) changed from 32.1 to 26.2 kg/m2, corresponding to a mean weight loss of 16.2 +/- 2.4 (SD) kg. The mean loss of TBN was 125 +/- 57 g, equivalent to 781 +/- 356 g protein. The fat-free mass (FFM) component of the weight loss was calculated by two different methods as 23.5% (+/- 3% SEM) and 22.8% (+/- 2.7% SEM), respectively, thereby demonstrating the improved protein sparing of ketogenic VLCDs. FFM loss was not clearly related to BMI.

Adult↗
PubMed1992

Across-the-day monitoring of mood and energy intake before, during, and after a very-low-calorie diet.

Mood, hunger, and energy intake were monitored in eight obese women before, during, and after 2 wk on a very-low-calorie diet (VLCD). Energy intake was significantly lower by approximately 30% in the week after the VLCD compared with the prediet week, both from food diaries and at a controlled ad libitum test meal. There was a gradual reduction in hunger, irritability, and urge to eat after 1 wk on the VLCD, which persisted through the postdiet week. Hunger and discontent were greatest in the evening during the first few days of the VLCD but diminished as the duration of the VLCD increased.

Affect↗
PubMed1992

Long-term outcome of a self-help very-low-calorie-diet weight-loss program.

This paper presents 90-wk data on five seriously overweight subjects originally brought together for 1-2 wk in simple residential accommodation to share the experience of beginning a program of very-low-calorie dieting. All subjects have remained well below their starting weight; four of the five subjects have continued to lose weight (weight losses 33.7-66.8 kg), now weighing less than at the end of the first 26 wk previously reported (1). It is proposed that this self-help group model, incorporating a very-low-calorie diet, is valuable for the long-term management of obesity.

Behavior Therapy↗
PubMed1992

Glycogen storage: illusions of easy weight loss, excessive weight regain, and distortions in estimates of body composition.

Glycogen is stored in the liver, muscles, and fat cells in hydrated form (three to four parts water) associated with potassium (0.45 mmol K/g glycogen). Total body potassium (TBK) changes early in very-low-calorie diets (VLCDs) primarily reflect glycogen storage. Potassium released from glycogen can distort estimates of body composition during dieting. TBK changes due to glycogen mobilization were measured in 11 subjects after 4 d dieting with a VLCD. The influence of water-laden glycogen on weight fluctuations during the dieting process, the exaggerated regain if carbohydrate loading occurs, and the implications for weight control programs and overestimation of nitrogen losses with dieting are discussed.

Body Composition↗
PubMed1991

Effect of changes of water and electrolytes on the validity of conventional methods of measuring fat-free mass.

Fat-free mass was measured by hydrodensitometry, electrical impedance and total body potassium before and after water and electrolyte loss induced by (a) the administration of the diuretic frusemide, and (b) sweat loss. All methods of measuring fat-free mass were shown by pilot experiments to have procedural reliability. The diuretic caused a reduction in apparent fat-free mass of 2.63 kg by the impedance method, of 2.33 kg by hydrodensitometry and of 1.8 kg by total body potassium. Water and electrolyte loss from sweating caused a fat-free loss of 2.3 kg, 2.7 kg and 1.3 kg by the same three procedures. Urinary potassium accounted for about one fifth of the observed 40K fat-free mass loss. Each method was thus clearly sensitive to the induced water loss. These data suggest that in evaluating the composition of weight loss, existing methods of measuring body composition do not distinguish between water and other more critical components of fat-free mass. It is thus essential that stable hydration levels are established for any longitudinal comparison of weight loss by these methods.

Adipose Tissue↗
PubMed1989

Selection of appropriate exercise regimens for weight reduction during VLCD and maintenance.

Body composition, resting metabolic rate (RMR) and physical work capacity (aerobic capacity) were measured in four groups of 10 overweight women during 8 weeks of VLCD (405 kcal/day (42 g protein] followed by 8 weeks of 1500 kcal/day maintenance with two additional non dieting groups as controls. Five groups, i.e. two control groups plus three dieting groups, undertook exercise in bicycle ergometry (aerobic) or isotonic resistance or 8 week ergometry followed by 8 week resistance. Weight loss and body composition patterns were similar in diet and diet and exercise groups but efficiency of residual FFM in isotonic resistance groups improved significantly (P less than 0.05). Strength gains/kg body weight significantly improved (P less than 0.05) in the isotonic and dieting group. We conclude that exercise with VLCD is beneficial particularly isotonic resistance training, in improving muscular efficiency and RMR/lean.

Adult↗
PubMed1988

Inhibition of E rosetting and of OKT 11 in patients with oral dysplasia and neoplasia.

A group of patients with oral dysplastic or early neoplastic lesions has been followed for 6 years to examine the change in ALS (antilymphocyte serum) induced 25% E rosette inhibition during the course of their disease. Control patients with other oral problems were examined similarly. The E rosette inhibition titer differences seen in our previous studies between control and diseased patients do not appear to persist with a longitudinal examination of these patients. While at early examination the patients exhibit higher inhibition titers than controls, later analysis shows that they seem to return to normal. To improve methodology, inhibition of OKT 11 uptake was substituted for E rosette inhibition and it is clear that both methods measure the same phenomenon. Thus, the former is more accurate and quantitative than the latter and will be used in future work. Continuation of these studies with the examination of more patients will be of value in assessing possible T lymphocyte changes in patients with oral lesions.

Antigens, Surface↗
PubMed1986

Spontaneous human meal patterns are related to preprandial factors regardless of natural environmental constraints.

There is a positive relationship between the amount people eat in a meal and the length of time since the previous meal (preprandial correlation). This study attempted to ascertain whether this correlation occurs due to environmental constraints on eating. Eight male and 30 female undergraduate students were instructed to list everything they ate and when they ate it. They were asked to make a recording in a diary of their eating and drinking throughout a 9 day period. They were also instructed to indicate whether the meal was spontaneous, in response to hunger or the desire for food, or constrained, determined by external factors. The amount of food energy in each meal was then calculated, and the amount remaining in the stomach at the beginning and end of each meal was estimated with a mathematical model. These data were then correlated with the duration of the intervals preceding and following the meals. The amount eaten in the meals was found to be predictable on the basis of preprandial factors regardless of whether the meal was initiated spontaneously or under environmental restrictions. Significant preprandial correlations were found for both constrained and spontaneous meals. No relationship was found between the amount ingested in the meal and the following interval (postprandial correlation) even when only the meals preceding a spontaneous meal were correlated. There were no significant correlations between the proportion of the meals that were constrained and the magnitude of either the preprandial or postprandial correlations. The findings suggest that humans initiate eating either in response to an externally determined schedule or to a learned schedule when constraints are not present.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1984

Safety and effectiveness of weight reduction using a very-low-calorie formulated food.

Careful medical and laboratory monitoring of 27 subjects during a 28-day use of a 330-calorie (Cal)/day liquid formula, with weight loss averaging 9.1 kg (range, 3.2 to 19.1 kg), included a 22-factor automated blood chemistry analysis, BP, hematology, urine analysis, lipid profile, delayed cutaneous hypersensitivity, differential cell count, ECG, and Holter monitoring. Results suggest that very-low-calorie diets can be an effective and safe means of substantial weight reduction. Cautions for specific individuals are noted. The possible beneficial effects on hypertension and on serum cholesterol and triglycerides levels are discussed.

Blood Proteins↗
PubMed1981

Relationship of vitamin A intake and E rosette inhibition to oral dysplasia and neoplasia.

The present study investigated the 25% E rosette inhibition titer and vitamin A intake levels of patients with dysplastic or neoplastic lesions of the oral cavity as compared to control subjects with or without a variety of other oral diseases. All subjects were followed with repeat examinations beginning at the time of entry in the study and approximately every 6 months thereafter. E rosette inhibition titers generally increased as the lesions became more dysplastic. In the control group titers remained at a low level throughout the study. Vitamin A intake levels were mostly below one-half or above twice the recommended daily allowance in patients with dysplasias and in a few controls with nondysplastic oral disease. Some patients with dysplasias were in the normal range. The results of vitamin A measurements were compatible with a variety of studies suggesting a role for vitamin A in the genesis of epithelial dysplasias. The pattern of observed E rosette inhibition titers was in keeping with previous work in our laboratory as well with that of others who described a correlation between the height of titers and the degree of dysplasia.

Adult↗