title: Serum leptin and insulin levels during chronic diurnal fasting.
abstract: Ramadan fasting is a unique model that is associated with restriction of the timing of food and fluid intake food from dawn to sunset and reduction in meal frequency and sleep duration. Leptin levels are thought to play a role in long-term regulation of caloric intake and fat deposition. However, the long-term changes in leptin levels during this pattern of fasting are not known. The study was conducted on lean (N=6, BMI=22.5+/-0.4) and obese (N=18, BMI=33.1+/-1.0) healthy female volunteers. Fasting serum levels of leptin, insulin and glucose were estimated at baseline (day 1), days 14 and 28 of the month of Ramadan and 2 weeks after Ramadan. Baseline serum levels of leptin were significantly higher in obese (13.5+/-1.96 microg/L,P<0.05) compared with lean subjects (9.60+/-0.80 microg/L) and correlated positively with body fat (r=0.82, P=0.0004). Serum leptin levels exhibited a significant and comparable increase by 39% and 37% throughout the month in lean and obese subjects, respectively. In addition, a significant correlation (r=0.52, P=0.003) was found between changes in serum leptin and serum insulin levels. We conclude that chronic diurnal fasting is associated with significant elevations in serum leptin. These elevations appear to be mediated by changes in serum levels of insulin. These data support the role of insulin in the long-term regulation of leptin secretion during chronic diurnal fasting followed by nocturnal eating during the month of Ramadan.
authors.affiliation: Department of Physiology, College of Medicine and Medical Sciences, Arabian Gulf University, Manama, Kingdom of Bahrain. skassab@agu.edu.bh
authors.forename: Salah E
authors.initials: SE
authors.lastname: Kassab
authors.forename: Tarik
authors.initials: T
authors.lastname: Abdul-Ghaffar
authors.forename: Das S
authors.initials: DS
authors.lastname: Nagalla
authors.forename: Usha
authors.initials: U
authors.lastname: Sachdeva
authors.forename: Usha
authors.initials: U
authors.lastname: Nayar
mesh_terms: D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000097:blood; D001786:Blood Glucose / Q000378:metabolism; D002784:Cholesterol / Q000097:blood; D002149:Energy Intake; D005215:Fasting / Q000097:blood*; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood*; D007514:Islam; D020738:Leptin / Q000097:blood*; D008875:Middle Aged; D009765:Obesity / Q000097:blood*; D013997:Time Factors; D014280:Triglycerides / Q000097:blood; D049629:Waist-Hip Ratio
chemical_list: D015415:Biomarkers; D001786:Blood Glucose; D007328:Insulin; D020738:Leptin; D014280:Triglycerides; D002784:Cholesterol