title: Food cues do not modulate the neuroendocrine response to a prolonged fast in healthy men.
abstract: BACKGROUND
  Dietary restriction benefits health and increases lifespan in several species. Food odorants restrain the beneficial effects of dietary restriction in Drosophila melanogaster. We hypothesized that the presence of visual and odorous food stimuli during a prolonged fast modifies the neuroendocrine and metabolic response to fasting in humans.
  
  
  METHODS
  In this randomized, crossover intervention study, healthy young men (n = 12) fasted twice for 60 h; once in the presence and once in the absence of food-related visual and odorous stimuli. At baseline and on the last morning of each intervention, an oral glucose tolerance test (OGTT) was performed. During the OGTT, blood was sampled and a functional MRI scan was made.
  
  
  RESULTS
  The main effects of prolonged fasting were: (1) decreased plasma thyroid stimulating hormone and triiodothyronine levels; (2) downregulation of the pituitary-gonadal axis; (3) reduced plasma glucose and insulin concentrations, but increased glucose and insulin responses to glucose ingestion; (4) altered hypothalamic blood oxygenation level-dependent (BOLD) signal in response to the glucose load (particularly during the first 20 min after ingestion); (5) increased resting energy expenditure. Exposure to food cues did not affect these parameters.
  
  
  CONCLUSIONS
  This study shows that 60 h of fasting in young men (1) decreases the hypothalamic BOLD signal in response to glucose ingestion; (2) induces glucose intolerance; (3) increases resting energy expenditure, and (4) downregulates the pituitary-thyroid and pituitary-gonadal axes. Exposure to visual and odorous food cues did not alter these metabolic and neuroendocrine adaptations to nutrient deprivation.
authors.affiliation: Department of General Internal Medicine, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Marieke
authors.initials: M
authors.lastname: Snel
authors.forename: Marjolein A
authors.initials: MA
authors.lastname: Wijngaarden
authors.forename: Maurice B
authors.initials: MB
authors.lastname: Bizino
authors.forename: Jeroen
authors.initials: J
authors.lastname: van der Grond
authors.forename: Wouter M
authors.initials: WM
authors.lastname: Teeuwisse
authors.forename: Mark A
authors.initials: MA
authors.lastname: van Buchem
authors.forename: Ingrid M
authors.initials: IM
authors.lastname: Jazet
authors.forename: Hanno
authors.initials: H
authors.lastname: Pijl
mesh_terms: D000293:Adolescent; D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D018592:Cross-Over Studies; D003463:Cues; D005215:Fasting / Q000097:blood* / Q000523:psychology; D005502:Food; D006801:Humans; D008297:Male; D009490:Neurosecretory Systems / Q000378:metabolism*; D009812:Odorants; D010775:Photic Stimulation / Q000379:methods; D013997:Time Factors; D055815:Young Adult
chemical_list: D001786:Blood Glucose