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Effects of Whey Protein Supplement on 4-Week Resistance Exercise-Induced Improvements in Muscle Mass and Isokinetic Muscular Function under Dietary Control.
Kim, CB, Park, JH, Park, HS, Kim, HJ, Park, JJ
Nutrients. 2023;15(4)
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The popularity of dietary supplements has steadily increased. Among dietary supplements, carbohydrate supplementation is the main source of energy for muscle contraction, whereas amino acid supplementation not only provides energy but also affects muscle protein synthesis and muscle recovery after resistance exercise. The aim of this study was to investigate the effect of whey protein supplementation on changes in muscle mass and isokinetic muscle function following resistance exercise while controlling the participants’ normal diet by providing three meals a day during the entire study period This study was a randomised, double-blind, placebo-controlled trial which recruited thirty-six men in their 20s and 30s. Participants were randomly assigned (1:1) to a whey protein supplement intake group (PSG) and a placebo intake group (CON). Results show that after four weeks of resistance exercise: - the change in muscle mass was significantly different between the two groups. The PSG showed significantly increased muscle mass, whereas the CON did not. - changes in body weight, body fat mass, and percent body fat were not significantly different between the two groups. - the PSG group showed significantly increased strength of both the dominant and non-dominant knees and shoulders, whereas the CON group did not. - muscular strength did not increase even after resistance exercise in the CON. - the PSG showed significantly increased endurance of the dominant knee and shoulder, whereas the endurance of the CON did not change. Authors conclude that whey protein supplementation promotes muscle mass increase and selective increases in muscular strength and endurance from resistance exercise. Thus, whey protein supplementation is practically effective independently of the normal diet.
Abstract
(1) The purpose of this study was to investigate the effect of whey protein supplementation under dietary control on improvements in muscle mass and function following resistance exercise training. (2) Thirty-two men were randomly assigned to a whey protein supplementation group taking whey protein isolate (PSG, n = 17) and a placebo group (CON, n = 15). Participants were provided with three meals per day corresponding to the estimated individual daily energy intake. The supervised resistance exercise program was conducted 60 min per day, six days per week, for four weeks. (3) Post-intervention, there was a significant interaction between groups in terms of muscle mass increase (p = 0.033, η2 = 0.14), with a greater increase in the PSG. There were also significant interactions between the groups and increases in peak torque of the dominant knee flexors (p = 0.048, η2 = 0.12), dominant shoulder extensors, and non-dominant shoulder extensors (p = 0.028, η2 = 0.15; p = 0.015, η2 = 0.18), and the total work of the dominant knee and shoulder extensors (p = 0.012, η2 = 0.19; p = 0.013, η2 = 0.19), with greater increases in the PSG. (4) These results suggest that whey protein supplementation enhances resistance exercise-induced increase in muscle mass and overall muscular strength and endurance, independent of dietary influence.
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Timing of daily calorie loading affects appetite and hunger responses without changes in energy metabolism in healthy subjects with obesity.
Ruddick-Collins, LC, Morgan, PJ, Fyfe, CL, Filipe, JAN, Horgan, GW, Westerterp, KR, Johnston, JD, Johnstone, AM
Cell metabolism. 2022;34(10):1472-1485.e6
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Recent research has shown that the time of the day when a larger meal is consumed may influence energy utilisation, positively affecting weight loss. This randomised, crossover, isocaloric and eucaloric controlled feeding trial compared morning-loaded calorie intake with evening-loaded calorie intake to assess its effects on weight and metabolism. Thirty healthy, overweight, or obese individuals participated in this study for four weeks and assessed their energy intake and energy expenditure. Based on the findings of this study, there were no discernible variations in either resting metabolic rate or total energy expenditure based on the timing of energy intake. Morning loaded diet can significantly lower hunger and improve satiety compared to the evening-loaded diet. Because of these effects, a morning-loaded diet may aid weight loss through behavioural adaptations. Healthcare professionals can use the results of this study to understand the benefits of morning-loaded calorie intake in terms of hunger suppression and increased satiety which may promote weight loss through behavioural change. Further robust studies are required to evaluate the metabolic outcomes and energy metabolism followed by morning-loaded energy intake and evening-loaded energy intake.
Abstract
Morning loaded calorie intake in humans has been advocated as a dietary strategy to improve weight loss. This is also supported by animal studies suggesting time of eating can prevent weight gain. However, the underlying mechanisms through which timing of eating could promote weight loss in humans are unclear. In a randomized crossover trial (NCT03305237), 30 subjects with obesity/overweight underwent two 4-week calorie-restricted but isoenergetic weight loss diets, with morning loaded or evening loaded calories (45%:35%:20% versus 20%:35%:45% calories at breakfast, lunch, and dinner, respectively). We demonstrate no differences in total daily energy expenditure or resting metabolic rate related to the timing of calorie distribution, and no difference in weight loss. Participants consuming the morning loaded diet reported significantly lower hunger. Thus, morning loaded intake (big breakfast) may assist with compliance to weight loss regime through a greater suppression of appetite.
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Effect of menstrual cycle on resting metabolism: A systematic review and meta-analysis.
Benton, MJ, Hutchins, AM, Dawes, JJ
PloS one. 2020;15(7):e0236025
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Resting metabolic rate (RMR) plays a key role in energy balance and weight management. For more than 20 years, researchers have controlled for menstrual cycle fluctuations when designing studies that require measurement of RMR in young women. In fact, data regarding the influence of menstrual cycle on metabolism are inconsistent. The aim of this study was to systematically review and analyse existing research to determine whether the menstrual cycle influences RMR in women. This study is a systematic review and meta-analysis of thirty studies. Results show that when all studies were considered, the menstrual cycle exerted a small, but statistically significant effect on RMR in women. Specifically, RMR was found to be greater during the luteal phase compared to the follicular phase. However, when only larger studies (of more than 10 women) were considered, the effect of the menstrual cycle was slightly reduced, and when only studies published since 2000 were considered, the effect was even smaller and no longer significant. Authors conclude that researchers should be aware of the potential confounding influence of the menstrual cycle and control for it by testing consistently in one phase of the cycle when measuring RMR in premenopausal women.
Abstract
BACKGROUND The need to control for the potential influence of menstrual cycle phase on resting metabolism (RMR) places a burden on research participants who must self-report onset of menstruation and researchers who must schedule metabolic testing accordingly. PURPOSE To systematically review and analyze existing research to determine the effect of menstrual cycle on RMR. METHODS We searched PubMed, CINAHL, MEDLINE, SPORTDiscus, and Scopus databases using the search terms "menstrual cycle and metabolic rate" and "menstrual cycle and energy expenditure." Eligibility criteria were English language, single-group repeated measures design, and RMR as either a primary or secondary outcome. Risk of bias was assessed based on study sample, measurement, and control of confounders. Differences between the follicular and luteal phases of the menstrual cycle were analyzed using the standardized mean difference in effect size. RESULTS Thirty English-language studies published between 1930 and December 2019 were included in the systematic review, and 26 studies involving 318 women were included in the meta-analysis. Overall, there was a small but significant effect favoring increased RMR in the luteal phase (ES = 0.33; 95% CI = 0.17, 0.49, p < 0.001). DISCUSSION Limitations include risk of bias regarding measurement of both menstrual cycle and RMR. Sample sizes were small and studies did not report control of potential confounders. Sub-group analysis demonstrated that in more recent studies published since 2000, the effect of menstrual phase was reduced and not statistically significant (ES = 0.23; 95% CI = -0.00, 0.47; p = 0.055). Until larger and better designed studies are available, based on our current findings, researchers should be aware of the potential confounding influence of the menstrual cycle and control for it by testing consistently in one phase of the cycle when measuring RMR in pre-menopausal women.
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Thyroid hormones and changes in body weight and metabolic parameters in response to weight loss diets: the POUNDS LOST trial.
Liu, G, Liang, L, Bray, GA, Qi, L, Hu, FB, Rood, J, Sacks, FM, Sun, Q
International journal of obesity (2005). 2017;41(6):878-886
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The role of thyroid hormones in diet-induced weight loss and subsequent weight regain is largely unknown. The aim of this study was to examine the associations between thyroid hormones and changes in body weight and resting metabolic rate (RMR) in adults on a calorie-restricted diet. Data analysis was conducted among 569 overweight and obese adults with normal thyroid function participating in the 2-year Prevention of Obesity Using Novel Dietary Strategies (POUNDS) LOST clinical trial. Participants were assigned to diets that represented a reduced caloric intake of 750 kcal/day from estimated energy needs. Changes in body weight and RMR were assessed during the 2-year intervention. Thyroid hormones (free triiodothyronine (T3), free thyroxine (T4), total T3, total T4 and thyroid-stimulating hormone (TSH)), anthropometric measurements and biochemical parameters were assessed at baseline, 6 months and 24 months. Participants lost an average of 6.6 kg of body weight during the first 6 months and subsequently regained an average of 2.7 kg of body weight over the remaining period from 6 to 24 months. Baseline free T3, total T3 and free T4 were associated with baseline body weight, body mass index and RMR. Total T4 and TSH were not associated with these parameters. Higher baseline free T3 and free T4 levels were significantly associated with a greater weight loss during the first 6 months. Thyroid hormones did not predict weight regain in 6-24 months. In addition, changes in free T3 and total T3 levels were positively associated with changes in body weight, RMR, body fat mass, blood pressure, glucose, insulin, triglycerides and leptin at 6 months and 24 months. The authors concluded that on a reduced-calorie diet, higher baseline free T3 and free T4 predicted more weight loss, but not weight regain among overweight and obese adults with normal thyroid function. These findings reveal a role of thyroid hormones in body weight regulation and may help identify individuals more responsive to weight loss diets.
Abstract
BACKGROUND The role of thyroid hormones in diet-induced weight loss and subsequent weight regain is largely unknown. OBJECTIVES To examine the associations between thyroid hormones and changes in body weight and resting metabolic rate (RMR) in a diet-induced weight loss setting. SUBJECTS/METHODS Data analysis was conducted among 569 overweight and obese participants aged 30-70 years with normal thyroid function participating in the 2-year Prevention of Obesity Using Novel Dietary Strategies (POUNDS) LOST randomized clinical trial. Changes in body weight and RMR were assessed during the 2-year intervention. Thyroid hormones (free triiodothyronine (T3), free thyroxine (T4), total T3, total T4 and thyroid-stimulating hormone (TSH)), anthropometric measurements and biochemical parameters were assessed at baseline, 6 months and 24 months. RESULTS Participants lost an average of 6.6 kg of body weight during the first 6 months and subsequently regained an average of 2.7 kg of body weight over the remaining period from 6 to 24 months. Baseline free T3 and total T3 were positively associated, whereas free T4 was inversely associated, with baseline body weight, body mass index and RMR. Total T4 and TSH were not associated with these parameters. Higher baseline free T3 and free T4 levels were significantly associated with a greater weight loss during the first 6 months (P<0.05) after multivariate adjustments including dietary intervention groups and baseline body weight. Comparing extreme tertiles, the multivariate-adjusted weight loss±s.e. was -3.87±0.9 vs -5.39±0.9 kg for free T3 (Ptrend=0.02) and -4.09±0.9 vs -5.88±0.9 kg for free T4 (Ptrend=0.004). The thyroid hormones did not predict weight regain in 6-24 months. A similar pattern of associations was also observed between baseline thyroid hormones and changes in RMR. In addition, changes in free T3 and total T3 levels were positively associated with changes in body weight, RMR, body fat mass, blood pressure, glucose, insulin, triglycerides and leptin at 6 months and 24 months (all P<0.05). CONCLUSIONS In this diet-induced weight loss setting, higher baseline free T3 and free T4 predicted more weight loss, but not weight regain among overweight and obese adults with normal thyroid function. These findings reveal a novel role of thyroid hormones in body weight regulation and may help identify individuals more responsive to weight loss diets.