title: The effect of modified fasting on blood pressure and sympathetic activity: a correlation?
abstract: The effect of a low calorie diet (200 kcal/0.8 MJ) composed of 50 per cent glucose and 50 per cent protein was studied on blood pressure and sympathetic activity in eight normotensive obese subjects. The study lasted 21 days; during the first seven days (period I) a weight maintaining diet was given; this was followed by 14 d (period II) of modified fasting (200 kcal/0.8 MJ). Sodium and potassium intakes of 20 and 80 mmol per d respectively were maintained constant throughout the study. In period I blood pressure decreased slightly until day 5; this occurred concomitantly with a marked natriuresis. Thereafter blood pressure and sodium excretion remained stable. No significant change was observed in the urinary excretion of total catecholamines, noradrenaline and 4-hydroxy-3-methoxy mandelic acid. From the start of period II blood pressure decreased markedly, together with a significant decrease in the urinary excretion of the catecholamines and 4-hydroxy-3-methoxy mandelic acid. Both blood pressure and urinary excretion of catecholamines and 4-hydroxy-3-methoxy mandelic acid stabilized after day 7 of period II. These changes preceded the maximal sodium diuresis of severe calorie restriction. The results suggest a primary role for the sympathetic system in the hypotensive effect of short term calorie deprivation although some influence of natriuresis cannot be excluded.
mesh_terms: D000293:Adolescent; D000328:Adult; D001794:Blood Pressure; D001835:Body Weight; D002395:Catecholamines / Q000652:urine; D004038:Diet, Reducing; D004039:Diet, Sodium-Restricted; D005215:Fasting; D005260:Female; D006801:Humans; D009318:Natriuresis; D009765:Obesity / Q000178:diet therapy / Q000503:physiopathology* / Q000652:urine; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D014642:Vanilmandelic Acid / Q000652:urine
chemical_list: D002395:Catecholamines; D014642:Vanilmandelic Acid