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Early Time-Restricted Feeding Improves Insulin Sensitivity, Blood Pressure, and Oxidative Stress Even without Weight Loss in Men with Prediabetes.
Sutton, EF, Beyl, R, Early, KS, Cefalu, WT, Ravussin, E, Peterson, CM
Cell metabolism. 2018;27(6):1212-1221.e3
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Studies have shown that intermittent fasting (IF) can reduce body weight or body fat, as well as a number of metabolic markers. However, it is unknown whether the metabolic benefits are solely due to the weight loss. In addition, data from circadian studies suggest that eating earlier in the day has a positive effect on metabolism. The aim of this randomised, cross-over, controlled feeding trial was to evaluate the effects of early time-restricted feeding (eTRF) on weight and metabolic markers. eTRF was implemented as consuming all calories within a 6 hours window with the last meal no later than 3pm. 8 overweight men with prediabetes were randomized to either eTRF or a control schedule (12-hr feeding period) for 5 weeks, and later crossed over to the other schedule. During both eating regimes the same meals and calories were consumed in both groups in a controlled environment. eTRF improved insulin metabolism, blood pressure and oxidative stress, but not glucose levels, cholesterol or inflammatory markers. No weight loss occurred either during eTRF or control period, suggesting that the observed changes are independent of weight loss. The authors conclude that eTRF improves some aspects of cardiometabolic health and that these effects are not solely due to weight loss.
Abstract
Intermittent fasting (IF) improves cardiometabolic health; however, it is unknown whether these effects are due solely to weight loss. We conducted the first supervised controlled feeding trial to test whether IF has benefits independent of weight loss by feeding participants enough food to maintain their weight. Our proof-of-concept study also constitutes the first trial of early time-restricted feeding (eTRF), a form of IF that involves eating early in the day to be in alignment with circadian rhythms in metabolism. Men with prediabetes were randomized to eTRF (6-hr feeding period, with dinner before 3 p.m.) or a control schedule (12-hr feeding period) for 5 weeks and later crossed over to the other schedule. eTRF improved insulin sensitivity, β cell responsiveness, blood pressure, oxidative stress, and appetite. We demonstrate for the first time in humans that eTRF improves some aspects of cardiometabolic health and that IF's effects are not solely due to weight loss.
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Effect of A Very Low-Calorie Ketogenic Diet on Food and Alcohol Cravings, Physical and Sexual Activity, Sleep Disturbances, and Quality of Life in Obese Patients.
Castro, AI, Gomez-Arbelaez, D, Crujeiras, AB, Granero, R, Aguera, Z, Jimenez-Murcia, S, Sajoux, I, Lopez-Jaramillo, P, Fernandez-Aranda, F, Casanueva, FF
Nutrients. 2018;10(10)
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Obesity is a multi-factorial disorder involving genetic, environmental, metabolic and behavioural factors. Few studies have examined the effect of weight-loss therapy on various psychobiological parameters associated with obesity. Therefore the aim of this 4-month nutritional intervention was to evaluate food and alcohol cravings, physical activity levels, sleep quality, sexual function and quality of life in patients with obesity after following a very low-calorie ketogenic (VLCK) diet. Twenty obese patients were enrolled and participated in psychological questionnaires and anthropometric measurements at four points throughout the intervention: at baseline, maximum ketosis, reduced ketosis and endpoint. A specialist physician and expert dietician closely monitored participants to ensure safety and duration of the ketosis state. This study found that rapid and sustained weight loss induced by a VLCK-diet is associated with better food control and improvements in quality of life in obese subjects. Based on these results, the authors conclude a VLCK-diet is a suitable and valuable treatment option for obese patients.
Abstract
Psychological well-being and hunger and food control are two relevant factors involved in the success of weight-loss therapy in treating obesity. Thus, this study aims to evaluate food and alcohol cravings, physical and sexual activity, sleep, and life quality (QoL) in obese patients following a very low-calorie ketogenic (VLCK) diet, as well as the role of weight lost and ketosis on these parameters. A battery of psychological test was performed in twenty obese patients (12 females, 47.2 ± 10.2 year and BMI of 35.5 ± 4.4) through the course of a 4-month VLCK diet on four subsequent visits: baseline, maximum ketosis, reduced ketosis, and endpoint. Each subject acted as their own control. Relevantly, the dietary-induced changes in body composition (7.7 units of BMI lost, 18 kg of fat mass (1.2 kg of visceral fat mass)) were associated with a statistically significant improvement in food craving scores, physical activity, sleepiness, and female sexual function. Overall, these results also translated in a notable enhancement in QoL of the treated obese patients. Therefore, the rapid and sustained weight and fat mass (FM) loss induced by the VLCK diet is associated with good food control and improvements in the psychological well-being parameters in obese subjects, which could contribute to the long-term success of this therapy.
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Cardiovascular Biomarkers in Association with Dietary Intake in a Longitudinal Study of Youth with Type 1 Diabetes.
Sanjeevi, N, Lipsky, LM, Nansel, TR
Nutrients. 2018;10(10)
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Cardiovascular disease (CVD) is the major cause of mortality and morbidity in patients with type 1 diabetes, whose risk is several-fold higher than the general population. The objective of this study was to investigate relationships of CVD biomarkers with overall diet quality, and its dietary components in youth with type 1 diabetes. This study is a secondary analysis of a randomised controlled trial of a family-based behavioural nutrition intervention. The control group had an equal frequency of contact with the research staff but did not receive any nutrition advice besides that included as part of regular type 1 diabetes care. Results indicate that greater intake of whole grains and whole fruits, and lower added sugar and polyunsaturated fatty acids were associated with more favourable CVD biomarkers. Authors conclude that overall diet quality was not associated with CVD biomarkers in youth with type 1 diabetes. However, specific dietary components were associated with CVD biomarkers, independent of glycaemic control.
Abstract
Despite cardioprotective effects of a healthy diet in the general population, few studies have investigated this relationship in individuals with type 1 diabetes, who are at elevated risks of cardiovascular disease (CVD) due to hyperglycemia. The objective of this study was to examine the association of CVD biomarkers with overall diet quality, as measured by the Healthy Eating Index-2015 (HEI-2015), and its dietary components in youth with type 1 diabetes. Youth with type 1 diabetes (n = 136, 8⁻16.9 years) were enrolled in an 18-month behavioral nutrition intervention trial. Dietary intake from three-day diet records, CVD biomarkers (total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C); triglycerides (TG), C-reactive protein (CRP), 8-iso-prostaglandin-F2alpha (8-iso-PGF2α), systolic and diastolic blood pressure (SBP and DBP, respectively), and glycated hemoglobin (HbA1c) were assessed at baseline, 6, 12 and 18 months. Linear mixed-effects models estimated associations of dietary intake with CVD biomarkers, adjusting for HbA1c and other covariates. Separate models estimated associations of time-varying change in dietary intake with time-varying change in CVD biomarkers. HEI-2015 was not associated with CVD biomarkers, but whole grain intake was inversely associated with TC, HDL-C and DBP, and a greater increase in whole fruit intake was associated with lower DBP. Added sugar, saturated fat and polyunsaturated fat were positively related to serum TG, HDL-C, and DBP, respectively. Findings suggest that the intake of specific dietary components, including whole grains, whole fruits, added sugar and PUFA, may influence cardiometabolic health in youth with type 1 diabetes, independent of glycemic control.
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Effects of Three Commercially Available Sports Drinks on Substrate Metabolism and Subsequent Endurance Performance in a Postprandial State.
Qin, L, Wang, QR, Fang, ZL, Wang, T, Yu, AQ, Zhou, YJ, Zheng, Y, Yi, MQ
Nutrients. 2017;9(4)
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The depletion of stored glucose and the reduction of the availability of carbohydrates can contribute to fatigue during moderate-to-high intensity exercise. Studies have shown that carbohydrate consumption can reduce the depletion of stored energy and that the combination of protein and carbohydrate supplementation resulted in greater replenishment during intense exercise. Nowadays, most commercial sports beverages contain both carbohydrates and proteins. The present study looked at the postprandial effects of commercially available beverages on carbohydrate and fat metabolism and exercise performance. Ten healthy male participants with a history of running or cycling exercise participated in two studies in a double-blinded, counterbalanced manner. Commercially available beverages with low carbohydrate, high carbohydrate, and a combination of proteins and carbohydrates were tested, and it was found that a beverage containing both proteins and carbohydrates maintained insulin levels and provided greater energy during endurance exercise. It is important to conduct future studies on athletes with higher fitness levels to evaluate the benefits of commercially available beverages. Based on the findings of this study, healthcare professionals can learn more about the benefits of commercially available beverages that combine carbohydrates and proteins and have a low carbohydrate content.
Abstract
Purpose: To examine the effects of commercially available sports beverages with various components on substrate metabolism and subsequent performance. Methods: Two studies were conducted in a double-blinded, counterbalanced manner. Study I was designed to determine the glycemic index, while study II determined the utilization of substrates and subsequent exercise performance. Ten healthy male participants (age 21.70 ± 2.41 years, height 176.60 ± 5.23 cm, weight 66.58 ± 5.38 kg, V̇O2max 48.1 ± 8.4 mL/kg/min) participated in both study I and study II. Three types of commercially available sports beverage powders were used. The powders consisted primarily of oligosaccharides (low molecular weight carbohydrates, L-CHO), hydrolyzed starch (high molecular weight CHO, H-CHO), and whey protein powder with carbohydrate (CHO-PRO). They were dissolved in purified water with identical CHO concentration of 8% (w/v). In study I, each participant underwent two oral glucose tolerance tests (OGTT) and one glycemic response test for each sports drink. In study II, participants cycled for 60 min at 70% V̇O2max, one hour after consuming a standardized breakfast. One of four prescribed beverages (L-CHO, H-CHO, CHO-PRO, and Placebo control, PLA) was served at 0, 15, 30, 45 min during the exercise. Six hours after the first exercise session, participants came back for a "time to exhaustion test" (TTE). Blood samples were drawn at 0, 30, and 60 min in the first exercise session, while arterial blood gas analysis was conducted at 0, 30, and 60 min in both sessions. Subjective feelings (rating of perceived exertion and abdominal discomfort) were also evaluated every 30 min during exercise. Results: Compared to the reference standardized glucose solution, the glycemic index of the L-CHO beverage was 117.70 ± 14.25, while H-CHO was 105.50 ± 12.82, and CHO-PRO was 67.23 ± 5.88. During the exercise test, the insulin level at 30 and 60 min was significantly lower than baseline following the treatment of L-CHO, H-CHO, and PLA (p < 0.05). The CHO oxidation rate at 60 min in the first exercise session was significantly higher than that at 60 min in the second exercise session following the L-CHO treatment (p < 0.05). Time to exhaustion was not significantly different (p > 0.05). Conclusion: The CHO sports beverage with additional PRO maintains insulin production during endurance cycling at 70% V̇O2max in the postprandial state. L-CHO sports beverage suppresses fat utilization during the subsequent exercise performance test. The subsequent exercise performance (as evaluated by TTE) was not influenced by the type of CHO or the addition of PRO in the commercially available sports beverages used in the present study.
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Estrogen and progesterone exposure is reduced in response to energy deficiency in women aged 25-40 years.
Williams, NI, Reed, JL, Leidy, HJ, Legro, RS, De Souza, MJ
Human reproduction (Oxford, England). 2010;25(9):2328-39
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Diet and exercise are related to a reduction in breast cancer risk, and it is thought that this is at least partly due to their impact on levels of female sex hormones. This study aimed to test the effect that exercise and calorie restriction have on menstruation and sex hormones in premenopausal women. Inactive women aged 25-40 years were recruited for the study, and allocated to two groups. One group was assigned a low-calorie diet that provided 20-35% lower calories than baseline energy needs, plus 4 sessions of moderate-intensity exercise per week. The control group followed a diet designed to ensure weight maintenance, and took part in shorter exercise sessions twice a week. Women in the low-calorie group experienced a 15% reduction in levels of oestradiol and a 20% reduction in the levels of oestrogen metabolite oestrone glucuronide. Larger reductions in oestrone glucuronide were related to higher energy deficits, suggesting that hormone production is sensitive to day-to-day fluctuations in energy balance. There was no change in the menstrual cycles of the participants. The researchers concluded that an energy deficit is a more important factor in reducing oestrogen exposure than losing weight.
Abstract
BACKGROUND Alterations in circulating steroids are believed to be important mediators of the impact that diet and exercise have on breast cancer risk and changes in bone density. This study aimed to test the hypothesis that moderate exercise training combined with caloric restriction would produce significant menstrual disturbances and alterations in ovarian steroids in premenopausal women. METHODS Sedentary premenopausal women (25-40 years; body mass index: 23.6 +/- 0.6 kg/m(2)) assigned to either a light conditioning (LC, n = 9) or an exercise combined with caloric restriction group (EX + CR, n = 24) were studied for one screening, one baseline and four intervention periods equivalent to the length of subjects' menstrual cycles. Exercise consisted of supervised training sessions, i.e. two LC or four EX + CR times per week, 30-60 min at a moderate intensity. The EX + CR group was prescribed a diet representing a caloric restriction of 20-35% below baseline energy requirements, whereas the LC group remained eucaloric. Ovarian steroid exposure was determined with daily urinary estrone-1- and pregnanediol glucuronides (E1G and PdG, respectively) and mid-cycle urinary LH measures. Fitness, body composition, and serum sex hormone binding globulin (SHBG) and serum estradiol (E2) were assessed repeatedly. RESULTS The intervention produced significant increases in VO(2) max and decreases in both body weight (-3.7 +/- 0.5 kg; ranged from -8.8 to +1.8 kg) and percent body fat (-4.5 +/- 0.7%; ranged from -12 to +0.3%), which were attributable primarily to changes in the EX + CR subjects (time x group; P < 0.05). Serum E2 and urinary E1G and PdG concentrations declined significantly across the intervention period (time; P < 0.05), whereas SHBG increased transiently (time; P < 0.05) in the EX + CR subjects, with no significant changes observed in the LC group. The decrease in E1G area under the curve was significantly related to the daily energy deficit (R =0.61; P = 0.003), not the amount of weight lost. There was no significant impact of the intervention on menstrual cyclicity or the incidence of menstrual disturbances in either group. CONCLUSIONS A moderate aerobic exercise training program combined with modest weight loss in accordance with recommended guidelines produces significant reductions in ovarian steroid exposure without disrupting menstrual cyclicity in premenopausal women aged 25-40 years. Exposure to a daily energy deficit is a stronger predictor of the decline in estrogen exposure than decreases in body weight.