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Does four-week consecutive, dawn-to-sunset intermittent fasting during Ramadan affect cardiometabolic risk factors in healthy adults? A systematic review, meta-analysis, and meta-regression.
Jahrami, HA, Faris, ME, I Janahi, A, I Janahi, M, Abdelrahim, DN, Madkour, MI, Sater, MS, Hassan, AB, Bahammam, AS
Nutrition, metabolism, and cardiovascular diseases : NMCD. 2021;(8):2273-2301
Abstract
AIMS: This study aimed to evaluate the effects of Ramadan diurnal intermittent fasting (RDIF; 29-30 days) on cardiometabolic risk factors (CMRF) in healthy adults, and examine the effect of various cofactors on the outcomes using sub-group meta-regression. DATA SYNTHESIS We conducted a systematic review and meta-analysis to measure the effect sizes of changes in CMRF in healthy adult Muslims observing RDIF. Ten scientific databases (EBSCOhost, CINAHL, Cochrane, EMBASE, PubMed/MEDLINE, Scopus, Google Scholar, ProQuest Medical, ScienceDirect, and Web of Science) were searched from the date of inception (1950) to the end of November 2020. The CMRF searched and analyzed were total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), very low-density lipoprotein cholesterol (VLDL-C), diastolic blood pressure (DBP), and heart rate (HR). We identified 91 studies (4431 adults aged 18-85 years) conducted between 1982 and 2020 in 23 countries distributed over four continents. RDIF-induced effect sizes for CMRF were: TC (no. of studies K = 77, number of subjects N = 3705, Hedge's g = -0.092, 95% confidence interval (CI): -0.168, 0.016); TG (K = 74, N = 3591, Hedge's g = -0.127, 95% CI: -0.203, 0.051); HDL-C (K = 68, N = 3528, Hedge's g = 0.138, 95% CI: 0.051, 0.224); LDL-C (K = 65, N = 3354, Hedge's g = -0.115, 95% CI: -0.197, -0.034); VLDL-C (K = 13, N = 648, Hedge's g = -0.252, 95% CI: -0.431, 0.073), DBP (K = 32, N = 1716, Hedge's g = -0.255, 95% CI: -0.363, 0.147), and HR (K = 12, N = 674, Hedge's g = -0.082, 95% CI: -0.300, 0.136). Meta-regression revealed that the age of fasting people was a significant moderator of changes in both HDL-C (P = 0.02) and VLDL-C (P = 0.01). Male sex was the only significant moderator of changes in LDL-C (P = 0.055). Fasting time duration was the only significant moderator of HDL-C (P = 0.001) at the end of Ramadan. CONCLUSIONS RDIF positively impacts CMRF, which may confer short-term transient protection against cardiovascular disease among healthy people.
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Effects of intermittent fasting on body composition and clinical health markers in humans.
Tinsley, GM, La Bounty, PM
Nutrition reviews. 2015;(10):661-74
Abstract
Intermittent fasting is a broad term that encompasses a variety of programs that manipulate the timing of eating occasions by utilizing short-term fasts in order to improve body composition and overall health. This review examines studies conducted on intermittent fasting programs to determine if they are effective at improving body composition and clinical health markers associated with disease. Intermittent fasting protocols can be grouped into alternate-day fasting, whole-day fasting, and time-restricted feeding. Alternate-day fasting trials of 3 to 12 weeks in duration appear to be effective at reducing body weight (≈3%-7%), body fat (≈3-5.5 kg), total cholesterol (≈10%-21%), and triglycerides (≈14%-42%) in normal-weight, overweight, and obese humans. Whole-day fasting trials lasting 12 to 24 weeks also reduce body weight (≈3%-9%) and body fat, and favorably improve blood lipids (≈5%-20% reduction in total cholesterol and ≈17%-50% reduction in triglycerides). Research on time-restricted feeding is limited, and clear conclusions cannot be made at present. Future studies should examine long-term effects of intermittent fasting and the potential synergistic effects of combining intermittent fasting with exercise.
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Dynamics of fat absorption and effect of sham feeding on postprandial lipema.
Chavez-Jauregui, RN, Mattes, RD, Parks, EJ
Gastroenterology. 2010;(5):1538-48
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Abstract
BACKGROUND & AIMS Given the importance of postprandial hyperlipidemia to increase risk for atherosclerosis, in the present study, stable isotope-labeled meals were fed to healthy subjects (7 males and 3 females) to investigate the kinetics chylomicron synthesis and the effect of sensory exposure to lipid on metabolism. METHODS Subjects performed two, 24-hour inpatient studies that entailed consumption of a liquid formula evening meal containing 30 g of oil (+ (13)C(2) triolein) on day 1. Breakfast (day 2) consisted of triacylglycerols (TAGs) fed as capsules (30 g oil + (13)C(7) triolein) to avoid activation of mouth taste receptors. Next, modified sham feeding of cream cheese occurred over 2 hours. In the 2 trials, the stimulus was either higher fat (HF) or lower fat (LF) cream cheese. A liquid meal was consumed at lunch. Blood sampling occurred intermittently, and chylomicron particles S(f) >400 TAGs were analyzed by gas chromatography-mass spectrometry. RESULTS (13)C(2)-Label was found in fasting-state lipoproteins, and persons with higher body fat percentages showed greater dilution of meal TAGs from endogenous sources. For both trials, 13% ± 4% of lipoprotein TAGs oleic acid was derived from the previous evening meal. Incremental area under the curve for TAGs during HF was ∼2.5 times higher than after LF exposure (46 ± 15 vs 17 ± 5 μmol/L/h; P = .04). The greater HF morning lipemia occurred with elevated glucose, insulin, and nonesterified fatty acids peak after lunch. CONCLUSIONS These data support a connection between enteral lipid metabolism and oral fat exposure, resulting in elevated postprandial lipemia. The results suggest that the intestine may participate in a mechanism coordinating oral fat signaling with control of subsequent macronutrient disposal in the body.
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Exercise and postprandial lipemia: effect of continuous compared with intermittent activity patterns.
Miyashita, M, Burns, SF, Stensel, DJ
The American journal of clinical nutrition. 2006;(1):24-9
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BACKGROUND Guidelines state that accumulated physical activity is beneficial for health, but a minimum duration of 10 min per activity bout is recommended. Limited information regarding the effects of short (< 10 min) bouts of activity on health is available, and no studies of the effects of such short bouts of activity on postprandial lipemia have been conducted. OBJECTIVE The objective was to compare the effects of accumulating ten 3-min bouts of exercise with those of one 30-min bout of exercise on postprandial plasma triacylglycerol concentrations. DESIGN Ten men aged 21-32 y completed three 2-d trials > or = 1 wk apart in a randomized repeated-measures design. On day 1, the subjects rested (no exercise) or ran at 70% of maximum oxygen uptake in either ten 3-min bouts (30 min rest between each) or one continuous 30-min bout. On day 2, the subjects rested and consumed test meals (0.69 g fat, 0.95 g carbohydrate, 0.31 g protein, and 46 kJ/kg body mass) for breakfast and lunch. Venous blood samples were obtained in the fasted state and for 7 h postprandially on day 2. RESULTS Postprandial plasma triacylglycerol concentrations were lower throughout day 2 of both the accumulation exercise trial and the continuous exercise trial than during the control trial (main effect of trial: P < 0.001, 2-factor analysis of variance). CONCLUSIONS Accumulating multiple short bouts of exercise throughout the day effectively reduce postprandial plasma triacylglycerol concentrations to an extent similar to that of a single 30-min session of exercise in healthy young men.
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Effects on serum lipid profiles of continuous 17beta-estradiol, intermittent norgestimate regimens versus continuous combined 17beta-estradiol/norethisterone acetate hormone replacement therapy.
Ylikorkala, O, Lim, P, Caubel, P
Clinical therapeutics. 2000;(5):622-36
Abstract
OBJECTIVE To compare the effects of a daily oral 1-mg dose of continuous 17beta-estradiol (E2) plus intermittent (3 days off, 3 days on) norgestimate (NGM) 90 microg (n = 221), an oral 2-mg dose of continuous E2 plus intermittent NGM 180 microg (n = 219), and an oral 2-mg dose of continuous E2 plus continuous norethisterone acetate (NETA) 1 mg (n = 217) on blood lipids and lipoproteins in postmenopausal women. BACKGROUND The present study was undertaken because some progestins have adverse effects on lipid profiles, thereby negating the favorable effects of estrogens. METHODS This was a multicenter, randomized, parallel-group trial that focused primarily on the 2 marketed regimens--E2 1 mg/NGM 90 microg and E2/NETA. Both subjects and investigators were blinded to the intermittent regimens; the continuous combined regimen was administered open-label. After a minimum 12-hour overnight fast, blood samples were collected at baseline and during months 7 and 12 to determine lipid and lipoprotein concentrations using validated methods. RESULTS E2 1 mg/NGM 90 microg was associated with significant (ie, the 95% CI did not include 0) increases in high-density lipoprotein cholesterol (HDL-C) (6.8% [95% CI = 4.7%, 9.0%] and 4.8% [2.3%, 7.2%] at months 7 and 12, respectively) and high-density lipoprotein 2 cholesterol (HDL2-C) (10.8% [6.2%, 15.3%] and 24.1% [18.9%, 29.4%]) concentrations, and decreases in total cholesterol (-7.7% [-9.0%, -6.3%] and -9.2% [-10.5%, -7.9%]), low-density lipoprotein cholesterol (-14.3% [-16.3%, -12.4%] and -14.9% [-16.7%, -13.2%]), and lipoprotein(a) (-30.6% [-41.4%, -20.0%] at month 12) concentrations. A significant difference (P < 0.001 by analysis of variance) between the E2 1-mg/NGM 90-microg and NETA regimens was seen for HDL-C and HDL2-C concentrations, which were elevated in subjects receiving E2 1 mg/NGM 90 microg but reduced (-9.1% [-11.1%, -7.1%] and -12.3% [-14.3%, -10.3%] for HDL-C at months 7 and 12, respectively; -14.2% [-18.0%, -10.4%] and -2.5% [-7.8%, +2.8%] for HDL2-C at months 7 and 12, respectively) in those receiving E2/NETA. CONCLUSIONS In the present study, continuous E2 1 mg/NGM 90 microg was associated with beneficial effects on lipids and lipoproteins in healthy postmenopausal women, effects that were greater at least for HDL-C and HDL2-C than those observed with continuous combined E2/NETA. The applicability of the study results to women with preexisting cardiovascular disease or dyslipidemia, or those who are overweight, remains to be investigated.