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 -0.67

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2 support 11 contradict 0 tested null 2 mixed · 15 sources, 12 independent groups · 2 superseded — pooled inside a review, counted once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.

About Cochrane ↗ · Get involved / support ↗

Read the Cochrane review ↗

The evidence (17)

Source	Grade	Stance	Quality	Finding
Jiao M et al 2026 · study_type: meta-analysis	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 2015 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 2024 · EClinicalMedicine	meta-analysis	contradicts	high	Umbrella review of RCT meta-analyses: IF reduces total and LDL cholesterol vs controls, not raising LDL.
Cai 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 · study_type: observational	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 et al 2026 · study_type: animal	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 2014 · Obesity (Silver Spring)	RCT	contradicts	moderate	ADF with varied meal timing reduced LDL-C and CVD risk markers in obese adults.
Parvaresh 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 2019 · Cell Metab	RCT	contradicts	high	Strict ADF 4 wk lowered LDL and sICAM-1 in healthy non-obese humans; cardiovascular markers improved.
Klempel 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 2026 · Nutr Metab Cardiovasc Dis	meta-analysis	mixed	high	Umbrella review of meta-analyses: ADF/TRE/Ramadan IF generally lower or neutral on LDL-C; no consistent LDL increase.
Trepanowski JF, et al. (Varady) 2017 · JAMA Intern Med	RCT	supports	moderate	12-mo RCT: LDL increased in the ADF arm vs daily CR
Semnani-Azad 2025 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 et al 2025 · study_type: meta-analysis	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 et al 2026 · study_type: meta-analysis	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 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 et al] # corrected 2026-08-17 from PubMed; was [(IF body-comp SR/MA) 2025 · Nutr J	meta-analysis	contradicts	moderate	RCT meta-analysis in overweight/obese: IF improved cardiometabolic markers including LDL-C reductions.

Disagree, or know a study we missed?

We grade by evidence, not opinions. The way to weigh in is to point us to a study we haven't cited (check the evidence table above first), or to flag a problem with one we have. Every submission is reviewed; if it holds up, the grade updates and shows in Science Changes Its Mind.

📚 Suggest a study ⚑ Flag / request reclassification

Opens a short form. You'll sign in with Google so submissions are tied to a real account — we don't display your identity, and we only accept a link we can verify (PubMed, DOI, ClinicalTrials.gov).

Educational only, not medical advice. Grades and scores reflect published evidence weighted by study design and quality; see the methodology.