Die Auswirkungen einer kalorischen Restriktion auf die Körperfett-Verteilung und das Knochenfett

Obesity is a known risk factor for the development of insulin resistance and a key component of the metabolic syndrome. Especially visceral obesity is associated with increased cardiometabolic risk. In addition, accumulation of liver fat resulting in nonalcoholic fatty liver disease, is a major public health problem with the increase in the prevalence of obesity. Skeletal muscle is an important regulator of insulin homeostasis and accumulation of fat within muscle cells, intramyocellular lipids (IMCL), is strongly associated with measures of insulin resistance and may play an etiologic role in obesity-induced insulin resistance. Proton magnetic resonance spectroscopy (1H-MRS) is a noninvasive technique that can quantify IMCL and intrahepatic fat in vivo. We can also quantify abdominal fat compartments, including visceral adipose tissue (VAT) using MRI. In addition to increased cardiometabolic risk, elevated VAT, IMCL and intrahepatic lipids also have detrimental effects on bone. These fat deports are associated with decreased bone strength and increased fat content of bone marrow. Bone strength and marrow adipose tissue can be quantified non-invasively using high resolution CT and finite element analysis and 1H-MRS. Brown adipose tissue (BAT) is a fat compartment that is associated with energy expenditure and insulin sensitivity. BAT is prevalent in young individuals of normal weight. We can measure BAT using FDG-positron emission tomography (FDG-PET) with concomitant CT or MRI.
Description of imaging techniques and imaging examples of these fat depots will be provided. Changes in these fat depots in states of obesity, chronic undernutrition (anorexia nervosa) and short-term fasting (10 days) will be discussed.