Diets · Metabolic & Cardiometabolic

alternate-day fasting increases LDL cholesterol

In plain terms: Does fasting every other day raise bad cholesterol?

Refuted Diets 🔬 Includes disconfirming

Part of: 🥗 intermittent fasting

RefutedContestedStrong support

consensus score -0.74

No — most trials show no rise versus ordinary calorie cutting, with only one outlier suggesting harm.

📅 Last reviewed: 2026-07-15 ⓘ

Evidence ladder

How far up the ladder this claim has climbed. A high consensus on a low rung means "consistent so far," not "proven in people."

Top evidence so far: All trials, pooled (Meta-analysis)

MechanismIn-vitroAnimalObservationalRCTMeta-analysis

How the studies fall

2 support 10 contradict 0 tested null 1 mixed · 13 sources, 11 independent groups · 2 superseded — pooled inside a review, counted once

What the evidence shows

Alternate-day fasting raised LDL cholesterol vs daily calorie restriction at 12 months in one RCT - a possible-harm signal needing corroboration.

Cochrane has no ruling yet see how our grade compares ▾

Cochrane review 2021 · low to very low (GRADE) Not directly comparable

“Allaf 2021 (Cochrane CD013496.pub2) reviewed intermittent fasting (including alternate-day and modified alternate-day fasting) vs ad libitum feeding / continuous energy restriction for CVD prevention. LDL cholesterol was a reported lipid outcome (e.g. 'Absolute change in LDL (mmol/L)' comparisons); the review found no clinically important difference in cardiometabolic risk factors and rated the evidence low to very low certainty. Authors: 'The absolute effects of IF ... were small ... The quality of the available evidence was low to very low.' No signal that fasting raises LDL.”

Not directly comparable: their review asks a different question or reports an outcome we do not grade, so it neither corroborates nor contradicts this claim.

What is Cochrane, and why trust it?

Cochrane produces systematic reviews: instead of running a new study, they gather every trial ever done on a question, judge how well each was run, and pool the results. They take no commercial or industry funding, which is why the medical community treats their reviews as a gold standard — and why we check our own verdicts against theirs.

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The evidence (17)

Source	Grade	Stance	Quality	Finding
Jiao M, Yan H, Zhang B, Zhao X, Li J, Harun MT 2026 · Frontiers in nutrition	meta-analysis	contradicts	low	Multilevel meta-analysis of 65 RCTs (n=3293) on exercise + intermittent fasting found EX+IF reduced LDL-C along with total cholesterol, triglycerides, and IL-6 versus controls.
Varady KA, Dam VT, Klempel MC, Horne M, Cruz R, Kroeger CM, Santosa S 2015 · Sci Rep	RCT	contradicts	low	ADF decreased total cholesterol, LDL-C and TG with weight loss ⚠️ correction-on-file (Crossref) - kept, corrigendum not retraction
Sun ML, Yao W, Wang XY, Gao S, Varady KA, Forslund SK, Zhang M, Shi ZY, Cao F, Zou BJ, Sun MH, Liu KX, Bao Q, Xu J, Qin X, Xiao Q, Wu L, Zhao YH, Zhang DY, Wu QJ, Gong TT 2024 · EClinicalMedicine	meta-analysis	contradicts	high	Umbrella review of syntheses: 'A total of 351 associations from 23 meta-analyses with 34 health outcomes were included'. IF vs non-intervention in overweight/obesity lowered LDL-C (SMD -0.20; 95% CI -0.38 to -0.02); pooled IF, not ADF specifically. Review — zero weight.
Cai H, Qin YL, Shi ZY, Chen JH, Zeng MJ, Zhou W, Chen RQ, Chen ZY 2019 · BMC Gastroenterol	RCT	contradicts	moderate	ADF improved dyslipidaemia (reduced LDL/total cholesterol) and body weight in NAFLD patients. ↩ SUPERSEDED — pooled in the review above, counted once
Alfhaid F 2025 · Journal of family medicine and primary care	n-of-1	supports	low	Single case report: 42-year-old man on One-Meal-a-Day/IF regimen for 3 months lost ~10% body weight and improved HbA1c/BP, but LDL cholesterol 'paradoxically rose.'
Zhang Y, Huang Y, Xu Y, Li C 2026 · Nutrients	animal	contradicts	low	Mouse study (n=10/group, HFD-induced obesity) found ADF improved lipid profiles comparably to a tannin supplement, with both interventions activating AMPK-mTORC1-Lpin1 axis and suppressing lipogenesis; no LDL increase reported.
Hoddy KK, Kroeger CM, Trepanowski JF, Barnosky A, Bhutani S, Varady KA 2014 · Obesity (Silver Spring)	RCT	contradicts	moderate	ADF with varied meal timing reduced LDL-C and CVD risk markers in obese adults.
Parvaresh A, Razavi R, Abbasi B, Yaghoobloo K, Hassanzadeh A, Mohammadifard N, Safavi SM, Hadi A, Clark CCT 2019 · Complement Ther Med	RCT	contradicts	moderate	Modified ADF vs calorie restriction in metabolic syndrome: both lowered lipids; no LDL increase from ADF. ↩ SUPERSEDED — pooled in the review above, counted once
Stekovic S, Hofer SJ, Tripolt N, Aon MA, Royer P, Pein L, Stadler JT, Pendl T, Prietl B, Url J, Schroeder S, Tadic J, Eisenberg T, Magnes C, Stumpe M, Zuegner E, Bordag N, Riedl R, Schmidt A, Kolesnik E, Verheyen N, Springer A, Madl T, Sinner F, de Cabo R, Kroemer G, Obermayer-Pietsch B, Dengjel J, Sourij H, Pieber TR, Madeo F 2019 · Cell Metab	RCT	contradicts	high	Strict ADF 4 wk lowered LDL and sICAM-1 in healthy non-obese humans; cardiovascular markers improved.
Klempel MC, Kroeger CM, Varady KA 2013 · Eur J Clin Nutr	RCT	contradicts	moderate	ADF (high- or low-fat) lowered LDL-C 18-25% and increased LDL particle size in obese adults.
Popiolek-Kalisz J, Kwasny A 2026 · Nutr Metab Cardiovasc Dis	meta-analysis	mixed	high	Umbrella review, units are syntheses: 'Fifty-seven meta-analyses met the inclusion criteria.' 'ADF demonstrated inconsistent effects on lipid profile.' Review — zero weight.
Trepanowski JF, Kroeger CM, Barnosky A, Klempel MC, Bhutani S, Hoddy KK, Gabel K, Freels S, Rigdon J, Rood J, Ravussin E, Varady KA 2017 · JAMA Intern Med	RCT	supports	moderate	12-mo RCT: LDL increased in the ADF arm vs daily CR
Semnani-Azad Z, Khan TA, Chiavaroli L, Chen V, Bhatt HA, Chen A, Chiang N, Oguntala J, Kabisch S, Lau DC, Wharton S, Sharma AM, Harris L, Leiter LA, Hill JO, Hu FB, Lean ME, Kahleová H, Rahelic D, Salas-Salvadó J, Kendall CW, Sievenpiper JL 2025 · BMJ	meta-analysis	contradicts	high	IF strategies improved cardiometabolic markers; NO consistent LDL increase ⚠️ correction-on-file (Crossref) - kept, corrigendum not retraction
Song Q, Almutairi ASH, Almutairi MFA, Jamilian P, Abu-Zaid A 2025 · Frontiers in nutrition	meta-analysis	contradicts	moderate	GRADE-evaluated meta-analysis of 10 fasting studies (n=701) found various fasting regimens significantly reduced LDL-C (SMD -0.34, 95% CI -0.53 to -0.14, p=0.001), with high-quality evidence per GRADE.
Li H, Li T 2026 · Front Nutr	meta-analysis	contradicts	low	Systematic review/meta-analysis of 9 RCTs (n=894) in MASLD comparing IF (incl. ADF, TRF, 5:2) vs continuous energy restriction: IF associated with greater LDL-C reduction (MD -0.08 mmol/L, 95% CI -0.15 to -0.01) vs CER, not an increase.
Motiwala Z, Sarker P, Hliebov O 2025 · Cureus	observational	mixed	low	Meta-analysis: Ramadan intermittent fasting decreased LDL-C (Z=2.19, p=0.03) in South Asian populations.
Wang B, Wang C, Li H 2025 · Nutr J	meta-analysis	contradicts	moderate	RCT meta-analysis in overweight/obese: IF improved cardiometabolic markers including LDL-C reductions.

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