The Effect of Dietary Fat Load and Physical Exercise on the Flexibility and Partitioning of Ectopic Lipids.

This study aims at assessing the effect of standardized dietary fat load and short-term aerobic exercise on systemic lipolysis, flexibility and partitioning of ectopic fat stores (intramyocellular = IMCL, intrahepatocellular = IHCL, intramyocardial lipids = IMCaL) in relation to FFA in endurance trained athletes and hypopituitary patients compared to sedentary healthy control subjects. Exercise is a powerful stimulation for growth hormone (GH) secretion in health. A standardised exercise test can, therefore, be discriminative for the diagnosis of GH-deficiency in adults. This will be assessed. Hypothesis (ectopic fat stores) 1. Ectopic fats stores are flexible fuel stores and are influenced by diet and physical activity.FFA availability may play an important regulatory role. 2. There is a tissue specific partitioning of triglycerides and/or FFA among non-adipose organs after fat load and physical exercise 3. The flexibility of ectopic fat stores is related to insulin sensitivity 4. Lipolytic and anti-lipolytic hormones are critical for regulating FFA availability (at rest or during exercise) and therefore also for the regulation of ectopic fat stores. 5. GH is a lipolytica hormone. Lack of GH in adulthood is related to decreased FFA availability thereby influencing ectopic lipid stores Hypothesis diagnosis of GHD 6. A short intensive physical exercise shows a good discriminative power to diagnose GHD.