Does a low-carb diet affect cholesterol and triglycerides?

Yes, in two directions at once. Across 174 randomized trials in 11,481 adults, diets with 45 percent of energy or less from carbohydrate lowered triglycerides by 15 mg/dL, raised HDL by about 3 mg/dL and raised LDL by about 5 mg/dL compared with higher-carbohydrate diets. In meta-analyses of strict ketogenic diets, LDL rose more, by about 8 mg/dL. How much LDL rises depends strongly on body size. In trials whose participants averaged a BMI under 25 it went up by 41 mg/dL, and in trials averaging a BMI of 35 or more it fell slightly.

Established. Cutting carbohydrate lowers triglycerides and raises HDL cholesterol. Three meta-analyses of randomized trials agree on the direction, and in the 53-trial ketogenic analysis the reviewers rated certainty for both as moderate.

Unsettled. What happens to LDL, the cholesterol that statins target, is less settled and matters more. The same reviewers rated certainty for the LDL rise as low. The Cochrane review found little to no difference in cardiovascular risk factors over up to two years when low-carb was compared with a balanced weight-loss diet. No trial has followed people on these diets to heart attack, stroke or death, so nobody knows whether an LDL rise that comes with lower triglycerides and higher HDL carries the usual risk.

Fall in triglycerides against control diets, mg/dL

Each bar is how much further triglycerides fell on the low-carbohydrate diet than on the control diet, with the 95% confidence interval. The two ketogenic meta-analyses share many of the same trials, so they are not two independent confirmations. Sources: cards ev-lcch-01, ev-lcch-02 and ev-lcch-03 below.

Rise in LDL cholesterol against control diets, mg/dL

Each bar is how much more LDL rose on the low-carbohydrate diet than on the control diet, with the 95% confidence interval. The last bar comes from the subset of trials whose participants averaged a BMI under 25. In trials at BMI 35 and above, LDL fell slightly instead. Sources: cards ev-lcch-03, ev-lcch-01, ev-lcch-02 and ev-lcch-05 below.

What the trials found

Ketogenic diets

A 2026 meta-analysis of 53 randomized trials of ketogenic diets, defined as more than 45 percent fat and under 10 percent carbohydrate, found triglycerides 22 mg/dL lower (95% CI 15.72 to 28.90), HDL 3.5 mg/dL higher and LDL 8 mg/dL higher (95% CI 5.08 to 11.40) than on control diets. A second 2026 meta-analysis of 62 trials found almost the same numbers, which is expected since the two pools overlap heavily. A 2026 network meta-analysis of 47 trials in 3,450 adults aged 35 to 75 with at least one heart risk factor ranked ketogenic diets highest for LDL rise, 17 mg/dL (0.43 mmol/L) more than a low-fat, moderate-carbohydrate diet (95% CI 0.13 to 0.74). Those comparisons were partly indirect, and diets were grouped by macronutrient targets rather than by what foods people ate.

Milder carbohydrate cuts

The 174-trial meta-analysis pooled ketogenic, low-carbohydrate and moderate-carbohydrate diets together. Its authors concluded that moderate-carbohydrate diets offered balanced benefits, while ketogenic diets produced more weight loss and larger rises in LDL and total cholesterol.

Low-carb against another weight-loss diet

The 2022 Cochrane review of 61 randomized trials in 6,925 adults with overweight or obesity, with and without type 2 diabetes, compared low-carbohydrate with balanced-carbohydrate weight-loss diets. It found probably little to no difference in weight or in cardiovascular risk factors, LDL among them, at up to two years. Most of those trials were at high risk of bias, mainly from missing outcome data. In type 2 diabetes, a 2024 meta-analysis of 6 trials lasting more than 12 months found no significant difference in LDL, with HDL slightly higher and triglycerides slightly lower on low-carb.

Two long single trials

In a 12-month trial of 148 adults without heart disease or diabetes, a diet under 40 g of carbohydrate a day raised HDL by 7.0 mg/dL (95% CI 3.0 to 11.0) and cut triglycerides by 14.1 mg/dL more than a low-fat diet, with the triglyceride interval running from 0.8 to 27.4. In the two-year DIRECT trial of 322 adults with moderate obesity, 86 percent of them men, the ratio of total to HDL cholesterol fell by 20 percent on low-carb against 12 percent on low-fat.

Who should be careful

The people whose LDL rises most on these diets are the lean ones. That runs against intuition, since lean people are often the ones who adopt low-carb for health rather than weight.

Not for everyone. If your BMI is under 25 and you go low-carb or keto, have your LDL checked. Across trials of lean adults, LDL rose by 41 mg/dL (95% CI 19.6 to 63.3), and that comes from trial averages of body size rather than from individuals. A separate meta-analysis of just three small trials in normal-weight adults found LDL 42 mg/dL (1.08 mmol/L) higher and apoB 0.35 g/L higher on ketogenic diets. The US National Lipid Association's 2019 statement reviewed potential safety concerns of these diets especially for high-risk people, such as those with genetic lipid disorders.

The extreme end is rare and real. A lean 51-year-old woman's LDL rose from 142 to 555 mg/dL on a very-low-carbohydrate diet. She carried a variant in the ABCG5 gene, which affects how the body handles plant sterols, and her LDL fell 75 percent with a change of diet and the drug ezetimibe. That is a single case. A 2026 retrospective series of 14 people with ketogenic-diet-induced high cholesterol found LDL fell more than expected on ezetimibe, with no comparison group. Neither tells you how common such responses are.

What expert bodies say

The US National Lipid Association, in its 2019 scientific statement, wrote that the evidence showed mixed effects on LDL, with some studies showing an increase. It also noted the drop in triglycerides and how little data exists beyond two years. That statement predates the 2024 to 2026 meta-analyses above, which now put a number on the LDL rise and show where it is largest. We read the abstract only, because the full text is paywalled.

How we searched

Searched: a local copy of PubMed, queried on 7 October 2026 for low-carbohydrate, ketogenic or low-carb diets with LDL, cholesterol, triglycerides, lipids or lipoproteins. That returned 343 reviews, guidelines and trials, and 7 meta-analyses of lipid outcomes were taken forward. A second query across all study types for genetic and very high cholesterol on these diets returned 47 records, including the case report and case series above. ClinicalTrials.gov in our local copy had nothing. The web turned up the National Lipid Association statement and an observational study of lean keto dieters with very high LDL.

Included: eight meta-analyses, the Cochrane review among them, two randomized trials, one case report, one case series and one professional society statement.

Excluded: the DIETFITS trial, because its abstract reports weight but not lipids and we did not pull the full text. A 2003 trial already included in the meta-analyses. A 16-person study of lipoprotein subclasses, too small and only on surrogate markers. The KETO-CTA study of self-selected lean keto dieters, because it is observational with no randomized control diet and its 2025 plaque paper is under public methodological dispute. Ketogenic meta-analyses for epilepsy, PCOS, cancer and cognition, which measured other outcomes.

What we read: abstracts. The National Lipid Association abstract was confirmed through two separate Europe PMC requests. All 13 sources were checked against Retraction Watch, with no retractions.

What we could not get: the full text of the National Lipid Association statement, which is paywalled, and the lipid results of DIETFITS.

What would change this answer

A randomized trial with heart attack, stroke or death as its outcome. None exists for low-carb or ketogenic diets, and the longest lipid trials last two years.
A randomized imaging trial in lean people whose LDL rises sharply on keto, with a control diet. The KETO-CTA study (NCT05733325) follows such people but is observational, so it cannot answer the question on its own.
Higher certainty for the LDL rise itself. The GRADE rating is low, so a few well-run trials could move the average.
The DIETFITS lipid results, which would add one more year-long trial to the comparison.

The rest of the nutrient, in one place. Carbs: how much you need, and what cutting them really does → What it does, how much you need, who runs short, and what too much does, with the evidence level shown on every line.

The full guide

The same question for other foods (cholesterol)

Sources

ev-lcch-01 · Meta-analysis or systematic review · systematic review and meta-regression of randomized controlled trials · n = 53 RCTs
According to the GRADE assessment, there is moderate certainty regarding TG and HDL-C, while certainty for LDL-C and TC remains low.
Who: adults in RCTs of ketogenic diets (more than 45% fat, less than 10% carbohydrate) versus control diets
Effect: TG WMD -22.31 mg/dL (95% CI -28.90 to -15.72); HDL +3.52 (1.24 to 5.81); LDL +8.22 (5.08 to 11.40); total cholesterol +8.06 (3.04 to 13.07)
Certainty: GRADE moderate for TG and HDL, low for LDL and total cholesterol; no cardiovascular event data.
BMC Cardiovasc Disord, 2026 · checked 2026-10-07 · we read the abstract
ev-lcch-02 · Meta-analysis or systematic review · meta-analysis and meta-regression of randomized controlled trials · n = 62 studies
The ketogenic diet significantly improves triglycerides and HDL-C but also leads to modest increases in LDL-C.
Who: adults in randomized controlled trials of ketogenic diets
Effect: TG WMD -19.96 mg/dL (-26.10 to -13.81); HDL +3.61 (1.44 to 5.57); LDL +8.49 (5.45 to 11.52); total cholesterol +8.14 (3.41 to 12.88)
Certainty: Overlaps heavily with ev-lcch-01 (same question, same year, similar trial pool); not independent confirmation.
Endocr Pract, 2026 · checked 2026-10-07 · we read the abstract
ev-lcch-03 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized trials · n = 11481
Moderate-carbohydrate diets offered balanced benefits, whereas ketogenic diets produced greater weight loss but greater increases in LDL and total cholesterol.
Who: adults in randomized trials comparing diets with 45% of energy or less from carbohydrate to higher-carbohydrate diets
Effect: TG -15.11 mg/dL (-18.76 to -11.46); HDL +2.92 (2.10 to 3.74); LDL +4.81 (2.58 to 7.05); total cholesterol +4.32 (1.66 to 6.97)
Certainty: Pools ketogenic, low-carb and moderate-carb diets; effect labeled SMD by the authors but reported in mg/dL.
Am J Clin Nutr, 2025 · checked 2026-10-07 · we read the abstract
ev-lcch-04 · Meta-analysis or systematic review · Cochrane systematic review and meta-analysis of randomized controlled trials · n = 6925
There is probably little to no difference in weight reduction and changes in cardiovascular risk factors up to two years' follow-up, when overweight and obese participants without and with T2DM are randomised to either low-carbohydrate or balanced-carbohydrate weight-reducing diets.
Who: overweight and obese adults without and with type 2 diabetes in weight-reducing diet trials
Effect: little to no difference in weight (MD -2.1 lb (-0.93 kg) at 1-2 years), diastolic blood pressure and LDL cholesterol over 1 to 2 years
Certainty: Risk of bias mostly high (missing outcome data); GRADE moderate to very low; compares two weight-loss diets, not low-carb versus usual diet.
Cochrane Database Syst Rev, 2022 · checked 2026-10-07 · we read the abstract
ev-lcch-05 · Meta-analysis or systematic review · meta-analysis and meta-regression of randomized controlled trials with pooled individual participant data · n = 1379
For trials with mean baseline BMI <25, LDL cholesterol increased by 41 mg/dL (95% CI: 19.6, 63.3) on the LCD.
Who: adults consuming under 130 g/d carbohydrate in randomized controlled trials, mean duration 19.4 weeks
Effect: BMI under 25: LDL +41 mg/dL (19.6 to 63.3); BMI 25 to under 35: no change; BMI 35 or more: -7 mg/dL (-12.1 to -1.3); -2.5 mg/dL LDL change per BMI unit
Certainty: Trial-level BMI (ecological); saturated fat amount did not explain the variation; clinical meaning of isolated LDL rise unknown.
Am J Clin Nutr, 2024 · checked 2026-10-07 · we read the abstract
ev-lcch-06 · Meta-analysis or systematic review · meta-analysis of randomized controlled trials · n = 3 RCTs
A KD significantly increased TC by 1.47 mmol/L (95%CI, 0.72-2.22 mmol/L), LDL-C by 1.08 mmol/L (95%CI, 0.37-1.79 mmol/L), and apoB by 0.35 g/L (95%CI, 0.06-0.65 g/L).
Who: normal-weight (body mass index < 25 kg/m2) adults in randomized controlled trials
Effect: TC +1.47 mmol/L (0.72 to 2.22); LDL +42 mg/dL (14 to 69; metric: 1.08 mmol/L, 0.37 to 1.79); apoB +0.35 g/L (0.06 to 0.65); HDL +14 mg/dL (0.35 mmol/L); TG no difference
Certainty: Only three small trials.
Nutr Rev, 2023 · checked 2026-10-07 · we read the abstract
ev-lcch-07 · Meta-analysis or systematic review · network meta-analysis of randomized clinical trials · n = 3450
Ketogenic diets showed the largest increases in LDL cholesterol [0.43 mmol/L (0.13; 0.74)] total cholesterol [0.55 mmol/L (0.13; 0.96)] and HDL cholesterol [0.12 mmol/L (0.06; 0.18)], compared with the reference diet, whereas triglyceride responses differed, with high-carbohydrate diets increasing them [0.24 mmol/L (0.04; 0.43)].
Who: adults aged 35-75 years with at least one CVD risk factor in randomized clinical trials with macronutrient targets
Effect: ketogenic vs low-fat-moderate-carbohydrate: LDL +17 mg/dL (5 to 29; metric: 0.43 mmol/L, 0.13 to 0.74); total cholesterol +0.55; HDL +0.12; high-carbohydrate diets raised TG +21 mg/dL (0.24 mmol/L)
Certainty: Indirect comparisons; diets classed by macronutrient targets, not food quality.
Eur J Nutr, 2026 · checked 2026-10-07 · we read the abstract
ev-lcch-08 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized controlled trials · n = 6 RCTs
As with glycemic control, there were no significant differences in the changes in weight loss, blood pressure, and low-density lipoprotein cholesterol between long-term LCD and control diets.
Who: adults with type 2 diabetes in RCTs of low-carbohydrate diets for more than 12 months
Effect: HDL SMD 0.22 (0.04 to 0.41); TG SMD -0.19 (-0.37 to 0.02); no significant difference in LDL, HbA1c or weight
Certainty: Six trials; standardized effects only.
J Diabetes Investig, 2024 · checked 2026-10-07 · we read the abstract
ev-lcch-09 · Randomized controlled trial(s) · randomized parallel-group trial · n = 148
At 12 months, participants on the low-carbohydrate diet had greater decreases in weight (mean difference in change, -3.5 kg [95% CI, -5.6 to -1.4 kg]; P = 0.002), fat mass (mean difference in change, -1.5% [CI, -2.6% to -0.4%]; P = 0.011), ratio of total-high-density lipoprotein (HDL) cholesterol (mean difference in change, -0.44 [CI, -0.71 to -0.16]; P = 0.002), and triglyceride level (mean difference in change, -0.16 mmol/L [-14.1 mg/dL] [CI, -0.31 to -0.01 mmol/L {-27.4 to -0.8 mg/dL}]; P = 0.038) and greater increases in HDL cholesterol level (mean difference in change, 0.18 mmol/L [7.0 mg/dL] [CI, 0.08 to 0.28 mmol/L {3.0 to 11.0 mg/dL}]; P < 0.001) than those on the low-fat diet.
Who: 148 men and women without clinical cardiovascular disease and diabetes
Effect: HDL +0.18 mmol/L (+7.0 mg/dL; 3.0 to 11.0); TG -0.16 mmol/L (-14.1 mg/dL; -27.4 to -0.8); total/HDL ratio -0.44; weight -7.7 lb (-3.5 kg) vs low-fat
Certainty: NIH-funded; no cardiovascular event outcomes.
Ann Intern Med, 2014 · checked 2026-10-07 · we read the abstract
ev-lcch-10 · Randomized controlled trial(s) · randomized controlled trial, 2 years · n = 322
The relative reduction in the ratio of total cholesterol to high-density lipoprotein cholesterol was 20% in the low-carbohydrate group and 12% in the low-fat group (P=0.01).
Who: moderately obese subjects (mean age, 52 years; mean BMI 31; male sex, 86%)
Effect: relative reduction in total/HDL cholesterol ratio 20% low-carbohydrate vs 12% low-fat (P=0.01)
Certainty: 86% men, mostly from one workplace in Israel.
N Engl J Med, 2008 · checked 2026-10-07 · we read the abstract
ev-lcch-11 · Laboratory or animal data · case report · n = 1
In this case, her LDL-C concentration increased from 142 mg/dL to 555 mg/dL on a VLCD, and her plasma β-sitosterol level was very high at 12.8 mg/L.
Who: one 51-year-old woman, BMI 18.5 kg/m2
Effect: LDL 142 to 555 mg/dL on a VLCD; down 75% to 139 mg/dL with dietary cholesterol restriction and ezetimibe
Certainty: Single case; shows how extreme the response can be in lean people with sterol-handling variants.
J Clin Lipidol, 2025 · checked 2026-10-07 · we read the abstract
ev-lcch-12 · Laboratory or animal data · case series · n = 14
Here, we describe a retrospective case series of 14 patients with ketogenic diet-induced hypercholesterolemia who experienced larger-than-expected LDL-C reductions after ezetimibe therapy.
Who: 14 patients with ketogenic diet-induced hypercholesterolemia
Effect: larger-than-expected LDL reductions after ezetimibe
Certainty: Retrospective, no control group; hypothesis-generating.
Lipids Health Dis, 2026 · checked 2026-10-07 · we read the abstract
ev-lcch-13 · Position of an expert body · professional society scientific statement · n = —
The evidence reviewed showed mixed effects on low-density lipoprotein cholesterol levels with some studies showing an increase.
Who: adults considering low-carbohydrate and very-low-carbohydrate diets; high-risk individuals with genetic lipid disorders
Effect: mixed LDL effects; triglyceride reduction; minimal data beyond 2 years
Certainty: Professional society statement (2019), older than the 2024-2026 meta-analyses above.
Journal of Clinical Lipidology, 2019, 13(5):689-711.e1, National Lipid Association scientific statement · checked 2026-10-07 · we read the abstract

How this page was made. Evidence was extracted from primary sources into cards, every number was re-checked against the source, and the text was written from those cards. Bioma Learn has no human medical reviewer at this time, and we say so rather than invent one. Methodology. This is information, not medical advice.