Food Cues Do Not Modulate the Neuroendocrine Response to a Prolonged Fast in Healthy Men

Abstract

Introduction: 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. Subjects and 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. Conclusion: 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.

Visual food cues decrease postprandial glucose concentrations in lean and obese men without affecting food intake and related endocrine parameters

“…They demonstrated increased glucose and insulin concentrations in response to an oral glucose tolerance test due to the prolonged fasting period, but these effects were not modified by food cues (Snel, et al, 2012). Nevertheless, the very long period of fasting might have provoked a ceiling effect that could have masked any stimulatory effects of food cues.…”

The effects of short-term fasting on tolerance to (neo) adjuvant chemotherapy in HER2-negative breast cancer patients: a randomized pilot study

“…Larger randomized trials such as the DIRECT study (NCT02126449) are now ongoing to evaluate the impact of STF on tolerance to and efficacy of neoadjuvant chemotherapy in women with stage II or III BC. Because it is likely that the positive effects of STF will be enhanced if the period of fasting is prolonged [ 37 , 49 ], a very low calorie, low protein fasting mimicking diet (FMD) is used to ease the burden of prolonged fasting [ 50 ]. Prophylactic dexamethasone will be omitted in the FMD arm during the first 4 chemotherapy cycles to reduce its potentially counteractive metabolic effects.…”

Effects of short-term fasting on cancer treatment

“…IGF-1 and insulin stimulate proliferation and growth and inhibit apoptosis in response to calorie and protein availability through signalling via the IGF-1 receptor (IGF-1R) and insulin receptor isoform A (IR-A), respectively [50–53]. Serum IGF-1 levels decrease during STF [54–56], because low insulin levels cause growth hormone (GH) resistance of the liver, which inhibits hepatic IGF-1 production [54, 57, 58]. Both insulin and IGF-1 activate the Ras/mitogen-activated protein kinase (MAPK) and phosphatidylinositol-3-kinase (PI3K)/Akt pathways.…”