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The Gut Microbiota during a Behavioral Weight Loss Intervention.
Stanislawski, MA, Frank, DN, Borengasser, SJ, Ostendorf, DM, Ir, D, Jambal, P, Bing, K, Wayland, L, Siebert, JC, Bessesen, DH, et al
Nutrients. 2021;(9)
Abstract
Altered gut microbiota has been linked to obesity and may influence weight loss. We are conducting an ongoing weight loss trial, comparing daily caloric restriction (DCR) to intermittent fasting (IMF) in adults who are overweight or obese. We report here an ancillary study of the gut microbiota and selected obesity-related parameters at the baseline and after the first three months of interventions. During this time, participants experienced significant improvements in clinical health measures, along with altered composition and diversity of fecal microbiota. We observed significant associations between the gut microbiota features and clinical measures, including weight and waist circumference, as well as changes in these clinical measures over time. Analysis by intervention group found between-group differences in the relative abundance of Akkermansia in response to the interventions. Our results provide insight into the impact of baseline gut microbiota on weight loss responsiveness as well as the early effects of DCR and IMF on gut microbiota.
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Intermittent Fasting and Metabolic Health: From Religious Fast to Time-Restricted Feeding.
Hoddy, KK, Marlatt, KL, Çetinkaya, H, Ravussin, E
Obesity (Silver Spring, Md.). 2020;(Suppl 1):S29-S37
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Abstract
Over the past 10 to 15 years, intermittent fasting has emerged as an unconventional approach to reduce body weight and improve metabolic health beyond simple calorie restriction. In this review, we summarize findings related to Ramadan and Sunnah fasting. We then discuss the role of caloric restriction not only as an intervention for weight control, but importantly, as a strategy for healthy aging and longevity. Finally, we review the four most common intermittent fasting (IF) strategies used to date for weight management and to improve cardiometabolic health. Weight loss is common after IF but does not appear to be different than daily caloric restriction when compared directly. IF may also provide additional cardiometabolic benefit, such as insulin sensitization, that is independent from weight loss. While no specific fasting regimen stands out as superior at this time, there is indeed heterogeneity in responses to these different IF diets. This suggests that one dietary regimen may not be ideally suited for every individual. Future studies should consider strategies for tailoring dietary prescriptions, including IF, based on advanced phenotyping and genotyping prior to diet initiation.
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Impact of intermittent fasting on body weight in overweight and obese individuals.
Lima, CHR, Oliveira, IKF, Frota, KMG, Carvalho, CMRG, Paiva, AA, Campelo, V, Martins, MDCCE
Revista da Associacao Medica Brasileira (1992). 2020;(2):222-226
Abstract
OBJECTIVE To verify the relationship of intermittent fasting in the bodyweight of overweight and obese individuals through a systematic literature review. METHODS This is a systematic review based on randomized controlled trials. The articles were consulted in the databases: Science Direct, PubMed e BVS. This review was evaluated through the PRISMA recommendation. RESULTS After the selection process, four articles were included in this review, comparing intermittent fasting (IF) with calorie restriction diet (CRD) as a control group. In 2 studies using similar protocols, there was no significant reduction in body weight of overweight or obese subjects. In the other two studies using different protocols, weight loss was significant in the IF group compared to the CRD group. CONCLUSIONS Results did not provide evidence of the effect of intermittent fasting on weight loss in overweight or obese individuals.
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Effect of intermittent compared to continuous energy restriction on weight loss and weight maintenance after 12 months in healthy overweight or obese adults.
Headland, ML, Clifton, PM, Keogh, JB
International journal of obesity (2005). 2019;(10):2028-2036
Abstract
BACKGROUND AND OBJECTIVE Intermittent energy restriction (IER) is an alternative to continuous energy restriction (CER) for weight loss. There are few long-term trials comparing efficacy of these methods. The objective was to compare the effects of CER to two forms of IER; a week-on-week-off energy restriction and a 5:2 program, during which participants restricted their energy intake severely for 2 days and ate as usual for 5 days, on weight loss, body composition, blood lipids, and glucose. SUBJECTS AND METHODS A one-year randomized parallel trial was conducted at the University of South Australia, Adelaide, Australia. Participants were 332 overweight and obese adults, ages 18-72 years, who were randomized to 1 of 3 groups: CER (4200 kJ/day for women and 5040 kJ/day for men), week-on-week-off energy restriction (alternating between the same energy restriction as the continuous group for one week and one week of habitual diet), or 5:2 (2100 kJ/day on modified fast days each week for women and 2520 kJ/day for men, the 2 days of energy restriction could be consecutive or non-consecutive). Primary outcome was weight loss, and secondary outcomes were changes in body composition, blood lipids, and glucose. RESULTS For the 146 individuals who completed the study (124 female, 22 male, mean BMI 33 kg/m2) mean weight loss, and body fat loss at 12 months was similar in the three intervention groups, -6.6 kg for CER, -5.1 kg for the week-on, week-off and -5.0 kg for 5:2 (p = 0.2 time by diet). Discontinuation rates were not different (p = 0.4). HDL-cholesterol rose (7%) and triglycerides decreased (13%) at 12 months with no differences between groups. No changes were seen for fasting glucose or LDL-cholesterol. DISCUSSION AND CONCLUSION The two forms of IER were not statistically different for weight loss, body composition, and cardiometabolic risk factors compared to CER.
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The effect of intermittent compared with continuous energy restriction on glycaemic control in patients with type 2 diabetes: 24-month follow-up of a randomised noninferiority trial.
Carter, S, Clifton, PM, Keogh, JB
Diabetes research and clinical practice. 2019;:11-19
Abstract
AIMS: We investigated the effects of intermittent compared to continuous energy restriction on glycaemic control in patients with type 2 diabetes mellitus. METHODS Adults (N = 137) with type 2 diabetes (mean [SD] HbA1c level, 7.3% (56 mmol/mol) [1.3%] [14.2 mmol/mol]) were randomised to one of two diets for 12 months. The intermittent group (n = 70) followed a 2100-2500 kJ (500-600 kcal) diet 2 non-consecutive days/week and their usual diet for 5 days/week. The continuous group (n = 67) followed a 5000-6300 kJ (1200-1500 kcal) diet for 7 days/week. Follow-up occurred at 24 months, 12 months after the completed intervention. The primary outcome was change in HbA1c and the secondary outcome was weight loss. RESULTS Intention-to-treat analysis showed an increase in mean [SEM] HbA1c level at 24 months in both the continuous and intermittent groups (0.4% [0.3%] vs 0.1% [0.2%] respectively; P = 0.32) (4.4 [3.3 mmol/mol] vs 1.1 [2.2 mmol/mol]; P = 0.32), with a between-group difference of 0.3% (90% CI, -0.31 to 0.83%) (3.3 mmol/mol [90% CI, -3.2 to 9.1 mmol/mol]) outside the prespecified boundary of ± 0.5% (5.5 mmol/mol), so statistical equivalence was not shown. Weight loss was maintained (P < 0.001) at -3.9 kg [1.1 kg] in both groups at 24 months, with a between-group difference of 0.07 kg (90% CI, -2.5 to 2.6 kg) outside the prespecified boundary of ±2.5 kg. There were no significant differences between groups in body composition, fasting glucose levels, lipid levels, or total medication effect score at 24 months, which remained less than baseline. CONCLUSIONS In this prospective analysis weight loss was maintained but despite this HbA1c increased to above baseline levels in both groups.
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Compensatory mechanisms activated with intermittent energy restriction: A randomized control trial.
Coutinho, SR, Halset, EH, Gåsbakk, S, Rehfeld, JF, Kulseng, B, Truby, H, Martins, C
Clinical nutrition (Edinburgh, Scotland). 2018;(3):815-823
Abstract
BACKGROUND & AIMS Strong compensatory responses, with reduced resting metabolic rate (RMR), increased exercise efficiency (ExEff) and appetite, are activated when weight loss (WL) is achieved with continuous energy restriction (CER), which try to restore energy balance. Intermittent energy restriction (IER), where short spells of energy restriction are interspaced by periods of habitual energy intake, may offer some protection in minimizing those responses. We aimed to compare the effect of IER versus CER on body composition and the compensatory responses induced by WL. METHODS 35 adults (age: 39 ± 9 y) with obesity (BMI: 36 ± 4 kg/m2) were randomized to lose a similar weight with an IER (N = 18) or a CER (N = 17) diet over a 12 week period. Macronutrient composition and overall energy restriction (33% reduction) were similar between groups. Body weight/composition, RMR, fasting respiratory quotient (RQ), ExEff (10, 25, and 50 W), subjective appetite ratings (hunger, fullness, desire to eat, and prospective food consumption (PFC)), and appetite-regulating hormones (active ghrelin (AG), cholecystokinin (CCK), total peptide YY (PYY), active glucagon-like peptide-1 (GLP-1), and insulin) were measured before and after WL. RESULTS Changes in body weight (≈12.5% WL) and composition were similar in both groups. Fasting RQ and ExEff at 10 W increased in both groups. Losing weight, either by IER or CER dieting, did not induce significant changes in subjective appetite ratings. RMR decreased and ExEff at 25 and 50 W increased (P < 0.001 for all) in IER group only. Basal and postprandial AG increased (P < 0.05) in IER group, whereas basal active GLP-1 decreased (P = 0.033) in CER group only. Postprandial CCK decreased in both groups (P = 0.0012 and P = 0.009 for IER and CER groups, respectively). No between group differences were apparent for any of the outcomes. CONCLUSIONS The technique used to achieve energy restriction, whether it is continuous or intermittent, does not appear to modulate the compensatory mechanisms activated by weight loss. CLINICAL TRIAL REGISTRATION NUMBER NCT02169778 (the study was registered in clinicaltrial.gov).
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Impact of intermittent fasting on the lipid profile: Assessment associated with diet and weight loss.
Santos, HO, Macedo, RCO
Clinical nutrition ESPEN. 2018;:14-21
Abstract
Intermittent fasting, whose proposed benefits include the improvement of lipid profile and the body weight loss, has gained considerable scientific and popular repercussion. This review aimed to consolidate studies that analyzed the lipid profile in humans before and after intermittent fasting period through a detailed review; and to propose the physiological mechanism, considering the diet and the body weight loss. Normocaloric and hypocaloric intermittent fasting may be a dietary method to aid in the improvement of the lipid profile in healthy, obese and dyslipidemic men and women by reducing total cholesterol, LDL, triglycerides and increasing HDL levels. However, the majority of studies that analyze the intermittent fasting impacts on the lipid profile and body weight loss are observational based on Ramadan fasting, which lacks large sample and detailed information about diet. Randomized clinical trials with a larger sample size are needed to evaluate the IF effects mainly in patients with dyslipidemia.
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Is two days of intermittent energy restriction per week a feasible weight loss approach in obese males? A randomised pilot study.
Conley, M, Le Fevre, L, Haywood, C, Proietto, J
Nutrition & dietetics: the journal of the Dietitians Association of Australia. 2018;(1):65-72
Abstract
AIM: The 5:2 diet (two non-consecutive days of 2460 KJ (600 calories) and 5 days of ad libitum eating per week) is becoming increasingly popular. This pilot study aimed to determine whether the 5:2 diet can achieve ≥5% weight loss and greater improvements in weight and biochemical markers than a standard energy-restricted diet (SERD) in obese male war veterans. METHODS A total of 24 participants were randomised to consume either the 5:2 diet or a SERD (2050 KJ (500 calorie) reduction per day) for 6 months. Weight, waist circumference (WC), fasting blood glucose, blood lipids, blood pressure and dietary intake were measured at baseline, 3 and 6 months by a blinded investigator. RESULTS After 6 months, participants in both groups significantly reduced body weight (P = <0.001), WC (P = <0.001) and systolic blood pressure (P = 0.001). Mean weight loss was 5.3 ± 3.0 kg (5.5 ± 3.2%) for the 5:2 group and 5.5 ± 4.3 kg (5.4 ± 4.2%) for the SERD group. Mean WC reduction for the 5:2 group was 8.0 ± 4.5 and 6.4 ± 5.8 cm for the SERD group. There was no significant difference in the amount of weight loss or WC reduction between diet groups. There was no significant change in diastolic blood pressure, fasting blood glucose or blood lipids in either dietary group. CONCLUSIONS Results suggest that the 5:2 diet is a successful but not superior weight loss approach in male war veterans when compared to a SERD. Future research is needed to determine the long-term effectiveness of the 5:2 diet and its effectiveness in other population groups.
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Popular Weight Loss Strategies: a Review of Four Weight Loss Techniques.
Obert, J, Pearlman, M, Obert, L, Chapin, S
Current gastroenterology reports. 2017;(12):61
Abstract
PURPOSE OF REVIEW The purpose of this paper is to review the epidemiology of obesity and the most recent literature on popular fad diets and exercise regimens that are used for weight loss. The weight loss plans that will be discussed in this article include juicing or detoxification diets, intermittent fasting, the paleo diet, and high intensity training. RECENT FINDINGS Despite the growing popularity of fad diets and exercise plans for weight loss, there are limited studies that actually suggest these particular regimens are beneficial and lead to long-term weight loss. Juicing or detoxification diets tend to work because they lead to extremely low caloric intake for short periods of time, however tend to lead to weight gain once a normal diet is resumed. Both intermittent fasting and the paleo diet lead to weight loss because of overall decreased caloric intake as well. Lastly, studies on short bursts of high intensity training have shown remarkable weight loss and improvements in cardiovascular health. Review of the literature does suggest that some fad diets and exercise plans do lead to weight loss; however, the studies are quite limited and are all based on the concept of caloric restriction.
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Comparison of Intermittent Fasting Versus Caloric Restriction in Obese Subjects: A Two Year Follow-Up.
Aksungar, FB, Sarıkaya, M, Coskun, A, Serteser, M, Unsal, I
The journal of nutrition, health & aging. 2017;(6):681-685
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Abstract
OBJECTIVE Caloric restriction (CR) is proven to be effective in increasing life span and it is well known that, nutritional habits, sleeping pattern and meal frequency have profound effects on human health. In Ramadan some Muslims fast during the day-light hours for a month, providing us a unique model of intermittent fasting (IF) in humans. In the present study, we have investigated the effects of IF versus CR on the same non-diabetic obese subjects who were followed for two years according to the growth hormone (GH)/Insulin like growth factor (IGF)-1 axis and insulin resistance. DESIGN Single-arm Interventional Human Study. PARTICIPANTS 23 female subjects (Body Mass Index (BMI) 29-39, aged between 28-42years). SETTING Follow-up is designed as 12 months of CR, after which there was a month of IF and 11 months of CR again, to be totally 24 months. Subjects' daily diets were aligned as low calorie diet during CR and during the IF period, the same subjects fasted for 15 hours in a day for a month and there was no daily calorie restriction. Nutritional pattern was changed as 1 meal in the evening and a late supper before sleeping and no eating and drinking during the day light hours in the IF model. Subjects made brisk walking twice a day during the whole follow-up including both CR and IF periods. BMI, Blood glucose, insulin, TSH, GH, HbA1c, IGF-1, Homa-IR and urinary acetoacetate levels were monitored once in three months and twice in the fasting month. MEASUREMENTS AND RESULTS While subjects lost 1250 ± 372g monthly during the CR, in the IF period, weight loss was decreased to 473 ± 146 g. BMI of all subjects decreased gradually and as the BMI decreased, glucose, HbA1c, insulin, Homa-IR and TSH levels were decreased. GH levels were at baseline at the beginning, increased in the first six months and stayed steady during the CR and IF period than began decreasing after the IF period, while IGF-I increased gradually during the CR period and beginning with the 7th day of IF period, it decreased and kept on decreasing till the end of the follow-up. Urinary acetoacetate levels were higher during the IF period suggesting a constant lipid catabolism. CONCLUSION Our results suggest that, CR affects metabolic parameters positively which will help especially pre-diabetic and insulin resistant patients without any pharmacological approach. In addition IF without calorie restriction can enhance health and cellular resistance to disease without losing weight and those effects may be attributed to different signalling pathways and circulating ketones during IF. Changes observed during IF are probably due to the changes in eating and sleeping pattern and thus changes in metabolic rhythm.