Obesity is linked to a wide range of serious illnesses. In addition to the important impact on the health of the individual, obesity also has a substantial impact on the economy. Disruption of physiological day-night cycles could contribute to the increased incidence of obesity. According to the American National Sleep Federation, the percentage of the people who reported a sleep duration of six hours or less increased from 12 to 37 % over ten years. Insufficient sleep leads not only to an increase of the total calorie intake but changes the meal preference in favor of palatable foods and meals with high carbohydrate content. A decrease of leptin and increase of ghrelin levels caused by sleep deficiency can also play a role. In addition to the higher caloric intake, the timing of food consumption should be taken into account. The same meal eaten during the night versus the day is associated with increased postprandial glucose and triglyceride levels. The gut microbiome has also been recently understood as an endocrine system, with links between the gut microbiome and circadian rhythm changes possibly influencing increased obesity.

Chronic smoking alters the circulating levels of sex hormones and possibly also the neuroactive steroids. However, the data available is limited. Therefore, a broad spectrum of free and conjugated steroids and related substances was quantified by GC-MS and RIA in premenopausal smokers and in age-matched (38.9±7.3 years of age) non-smokers in the follicular (FP) and luteal phases (LP) of menstrual cycle (10 non-smokers and 10 smokers, in the FP, and 10 non-smokers and 8 smokers in the . Besides for the common https://doi.org/10.33549/physiolres.932164 104 Dušková et al. Vol. 61 Table 3. Comparison of the levels of C19 steroids, estradiol, SHBG (nmol/l) and related indices (U/l) in the sera of premenopausal female non-smokers and sex-and age-matched smokers in follicular and luteal phases of menstrual cycle (the data are shown as medians with quartiles in the parentheses). FOLLICULAR PHASE LUTEAL PHASE Non-smokers Smokers Non-smokers Smokers ANCOVA followed by LSD multiple comparisons Variable CF SF CL SL Dehydroepiandrosterone 7.8

Stárka L.; Rácz B.; Šrámková M.; Hill M.; Dušková M. Report / Vol. 116 (2015) Key words: Daily profile -Dehydroepiandrosterone -7-hydroxydehydroepiandrosterone -16-hydroxy-dehydroepiandrosterone -Food intake Abstract: Eight women of reproductive age with normal body mass index were given 5 standardised meals, and their hormonal milieu was determined during the course of the day. Plasma from 12 withdrawals was analysed for dehydroepiandrosterone and its 7-and 16-hydroxylated metabolites. Overall, there was a maximum in the levels of steroid hormones in the morning, followed by decreases throughout the day. There was also an additional significant decrease found for dehydroepiandrosterone and its 7α-hydroxyderivative in association with the consumption of main meals, but not for the 7β-isomer or 16α-hydroxyderivative. 40) Prague Medicalhttp://dx

Taste is important for food intake. The fetus first experiences taste through amniotic fluid, and later via mother’s milk. Early human experience with taste has a key importance for later acceptance of food. Dietary behavior is determined by the interaction of many different factors. The development of the olfactory and taste receptors begins at 7-8 weeks of gestation. An early sensitive period probably exists when flavor preference is established. Sweet taste is preferred in early childhood; this is the reason why children are at increased risk of over-consuming saccharides. Gustatory sensitivity declines with age. The threshold for the perception of each basic taste differs, and is established genetically. In this review, we summarize published data on taste preferences and its development and changes during life.

The aim of this study was to look for changes in the daily profile of steroid hormones after standardized food intake. Eight young women not taking contraceptives were followed from 5:30 a.m. till 9:30 p.m. before and 1 and 2 h after eating breakfast, snack, lunch, the second snack and dinner. The differences in steroid levels before and after meals were evaluated. As expected, glucose, C-peptide and ghrelin levels changed postprandially. The steroid hormones cortisol, progesterone, pregnenolone and dehydroepiandrosterone showed a decrease after main meals, whereas testosterone and dihydrotestosterone showed no significant dependence on food intake. Estrogen levels did not exhibit a significant nycthemeral rhythm, but estradiol decreased after main meals. In our study the known nycthemeral rhythm of LH, FSH, cortisol, progesterone and pregnenolone after food intake were confirmed, but significant changes after meals were also observed in the levels of cortisol, dehydroepiandrosterone, estradiol and SHBG.