Acute effects of the very low carbohydrate diet on sleep indices.
ABSTRACT We compared the effect of short-term consumption of a very low carbohydrate (VLC) diet over 48 h to a control mixed diet on sleep indices in healthy, non-obese men.
This study employed a repeated-measure design where subjects were given isocaloric (2400 kcal) diets and matching evening test meals (4 h before usual bed-time), which were either mixed low-fat, high carbohydrate (15.5%, 12.5% and 72% of energy from protein, fat and carbohydrate, respectively) or VLC (38%, 61% and < 1% of energy from protein, fat and carbohydrate, respectively). Polysomnographic testing was performed on the familiarization and control night, 4 h after the first VLC test meal (acute phase) and 48 h (ketosis phase) following commencement of the VLC diet.
Fourteen healthy, non-obese men (aged 18-35 years; body mass index 23.4 +/- 1.9 kg/m(2)) who were good sleepers took part in the study.
Objective sleep was recorded using a computerized sleep system. Urine ketone level was monitored with reagent strips before the evening test meals and at bed-time on the control night, during the VLC acute and ketosis phases. Blood glucose level was measured with a glucometer before the evening test meal until 120 min following the meal. Hunger and fullness were assessed immediately after the meal until bed-time with Likert scales.
The proportion of rapid-eye movement (REM) sleep to total sleep time was significantly reduced at the VLC acute and VLC ketosis when compared to the control night (P = 0.006; n = 11 and P = 0.05; n = 14, respectively). The percentage of slow wave sleep (SWS) significantly increased for both the VLC acute (17.7 +/- 6.7) and ketosis (17.8 +/- 6.1) phases compared to control (13.9 +/- 6.3), P = 0.02 for both phases.
In healthy, good sleepers, the VLC diet over the short-term promotes increases in the percentage of SWS (deep sleep stage 4) and a reduction in the percentage of REM sleep ('dreaming' sleep) compared to the control mixed diet. The sleep changes may be linked to the metabolism of the fat content of the VLC diet.
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ABSTRACT: Sleep has numerous important physiological and cognitive functions that may be particularly important to elite athletes. Recent evidence, as well as anecdotal information, suggests that athletes may experience a reduced quality and/or quantity of sleep. Sleep deprivation can have significant effects on athletic performance, especially submaximal, prolonged exercise. Compromised sleep may also influence learning, memory, cognition, pain perception, immunity and inflammation. Furthermore, changes in glucose metabolism and neuroendocrine function as a result of chronic, partial sleep deprivation may result in alterations in carbohydrate metabolism, appetite, food intake and protein synthesis. These factors can ultimately have a negative influence on an athlete's nutritional, metabolic and endocrine status and hence potentially reduce athletic performance. Research has identified a number of neurotransmitters associated with the sleep-wake cycle. These include serotonin, gamma-aminobutyric acid, orexin, melanin-concentrating hormone, cholinergic, galanin, noradrenaline, and histamine. Therefore, nutritional interventions that may act on these neurotransmitters in the brain may also influence sleep. Carbohydrate, tryptophan, valerian, melatonin and other nutritional interventions have been investigated as possible sleep inducers and represent promising potential interventions. In this review, the factors influencing sleep quality and quantity in athletic populations are examined and the potential impact of nutritional interventions is considered. While there is some research investigating the effects of nutritional interventions on sleep, future research may highlight the importance of nutritional and dietary interventions to enhance sleep.Sports medicine (Auckland, N.Z.). 05/2014; 44 Suppl 1:13-23.
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ABSTRACT: Free radicals and oxidative stress have been recognized as important factors in the biology of aging and in many age-associated degenerative diseases. Antioxidant systems deteriorate during aging. It is, thus, considered that one way to reduce the rate of aging and the risk of chronic disease is to avoid the formation of free radicals and reduce oxidative stress by strengthening antioxidant defences. Phytochemicals present in fruits, vegetables, grains, and other foodstuffs have been linked to reducing the risk of major oxidative stress-induced diseases. Some dietary components of foods possess biological activities which influence circadian rhythms in humans. Chrononutrition studies have shown that not only the content of food, but also the time of ingestion contributes to the natural functioning of the circadian system. Dietary interventions with antioxidant-enriched foods taking into account the principles of chrononutrition are of particular interest for the elderly since they may help amplify the already powerful benefits of phytochemicals as natural instruments with which to prevent or delay the onset of common age-related diseases.Oxidative Medicine and Cellular Longevity 01/2013; 2013:729804.
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ABSTRACT: Objective: To evaluate the effects of overeating (140% of energy requirements) a high-fat low-energy density diet (HF/LED, 1.05kcal/g), high-fat high-energy density diet (HF/HED, 1.60kcal/g), and high-carbohydrate (HC) LED (1.05kcal/g) for 2-days on subsequent 4-day energy intake (EI), activity levels, appetite, and mood. Design and Methods: Using a randomized cross-over design, energy expenditure and EI were standardized during overeating. Results: In 20 adults with a mean±SD BMI of 30.7±4.6kg/m(2) , EI was not suppressed until the second day after overeating and accounted for ˜30% of the excess EI. Reductions in EI did not differ among the 3 diets or across days. Overeating had no effect on subsequent energy expenditure but steps/day decreased after the HC/LED and HF/HED. Sleep time was increased after the HF/HED compared to both LEDs. After overeating a HF/HED vs. HF/LED, carbohydrate cravings, hunger, prospective food consumption, and sadness increased and satisfaction, relaxation, and tranquility decreased. Conclusions: Diet type, time, or their interaction had no impact on compensation over 4 days. No adaptive thermogenesis was observed. The HF/HED vs. HF/LED had detrimental effects on food cravings, appetite, and mood. These results suggest short-term overeating is associated with incomplete compensation.Obesity 08/2013; · 4.39 Impact Factor