1.
Changes in abdominal subcutaneous fat water content with rapid weight loss and long-term weight maintenance in abdominally obese men and women.
Laaksonen, DE, Nuutinen, J, Lahtinen, T, Rissanen, A, Niskanen, LK
International journal of obesity and related metabolic disorders : journal of the International Association for the Study of Obesity. 2003;(6):677-83
Abstract
OBJECTIVE Insulin resistance decreases blood flow and volume in fat tissue. We hypothesised that fat tissue nutritive blood flow and volume, and thereby water content, would increase during weight loss and weight maintenance in obese persons. DESIGN Longitudinal clinical intervention with a 9-week very-low-calorie diet (VLCD) followed by one year of weight maintenance. SUBJECTS Obese men (n=13) and women (n=14) with the metabolic syndrome. MEASUREMENTS Water content of abdominal subcutaneous fat tissue as estimated by a sensor on the skin surface measuring the dielectric constant at 300 MHz. Anthropometric measures of fatness and fat distribution. Biochemical measures related to insulin resistance. RESULTS Subjects lost 14.5+/-3.4% of body weight during the VLCD, and generally sustained this weight loss during weight maintenance. Insulin sensitivity as estimated by an index (qualitative insulin sensitivity check index) increased during the VLCD, and remained increased throughout weight maintenance. The dielectric constant increased from 23.3+/-2.3 to 25.0+/-2.1 (P<0.001) during the VLCD, and further to 27.8+/-1.9 (P<0.001) during weight maintenance, indicating an increase in the water content of subcutaneous fat. The increase in subcutaneous fat water content did not correlate with weight loss and other measures of adiposity during the VLCD, but there was an inverse correlation that strengthened in significance from baseline to 6, 9 and 12 mo (r=-0.32 to -0.64, P=0.079-0.002). Increases in subcutaneous fat water content also correlated with improvements in insulin sensitivity at 6, 9 and 12 months of weight maintenance (r=0.34-0.54, P=0.094-0.006). CONCLUSIONS Water content of abdominal subcutaneous adipose tissue increases with weight loss in obese persons with the metabolic syndrome, and may reflect increased subcutaneous fat tissue nutritive blood flow. The increase in water content correlates with the increase in insulin sensitivity, suggesting that weight loss and consequent improved insulin sensitivity could mediate the increase in abdominal subcutaneous fat hydration.
2.
Disorders of body water homeostasis.
Verbalis, JG
Best practice & research. Clinical endocrinology & metabolism. 2003;(4):471-503
Abstract
Disorders of body fluids are among the most commonly encountered problems in the practice of clinical medicine. This is in large part because many different disease states can potentially disrupt the finely balanced mechanisms that control the intake and output of water and solute. It therefore behoves clinicians treating such patients to have a good understanding of the pathophysiology, the differential diagnosis and the management of these disorders. Because body water is the primary determinant of the osmolality of the extracellular fluid, disorders of body water homeostasis can be divided into hypo-osmolar disorders, in which there is an excess of body water relative to body solute, and hyperosmolar disorders, in which there is a deficiency of body water relative to body solute. The classical hyperosmolar disorder is diabetes insipidus (DI), and the classical hypo-osmolar disorder is the syndrome of inappropriate antidiuretic hormone secretion (SIADH). This chapter first reviews the regulatory mechanisms underlying water and sodium metabolism, the two major determinants of body fluid homeostasis. The major disorders of water metabolism causing hyperosmolality and hypo-osmolality, DI and SIADH, are then discussed in detail, including the pathogenesis, differential diagnosis and treatment of these disorders.