Blood tests on a keto or low-carb diet
For people following a ketogenic or other low-carbohydrate way of eating, whether for weight, diabetes or another reason.
8 tests explainedAI-verified against cited sources. Awaiting expert reviewLast reviewed 2026-10-19
Low-carb and keto eating often lowers triglycerides and nudges HDL up a little, and it can lower glucose. LDL responses vary widely. LDL rises a lot in some people and barely moves or falls in others. Long-term evidence is still thin, so results are best read with that in mind.
The tests that matter most
Most important first. Each one links to its full page, where the note for this group sits near the top.
LDL Cholesterol
LDL responses to low-carb eating vary widely, from large rises to falls. In a meta-analysis of trials, LDL was slightly higher on average than on low-fat diets. An online survey of people who chose to take part, which is weak evidence, found the biggest rises in leaner people with low triglycerides and high HDL.
Sources: Nutrients (2020), Current Developments in Nutrition (2022) and National Lipid Association (2019)
- Usual adult range
- up to 99 mg/dL
Apolipoprotein B (ApoB)
ApoB counts the particles that can build plaque. In an observational UK Biobank study, where diet came from 24-hour diet questionnaires, people eating a low-carb, high-fat diet had higher average LDL and ApoB, and very high LDL was nearly twice as common. A study like this can't show that the diet caused the difference.
Source: JACC: Advances (2024)
- Usual adult range
- up to 90 mg/dL
Triglycerides
Triglycerides often fall on low-carb diets. The NLA lists lower triglycerides among the possible advantages, and a meta-analysis of trials found lower triglycerides than on low-fat diets.
Sources: National Lipid Association (2019) and Nutrients (2020)
- Usual adult range
- up to 149 mg/dL
HDL Cholesterol
HDL was slightly higher on low-carb diets than on low-fat diets in a meta-analysis of trials. In the online survey, high HDL with low triglycerides went along with the largest LDL rises.
Sources: Nutrients (2020) and Current Developments in Nutrition (2022)
- Usual adult range
- 40 and above mg/dL
Glucose
Low-carb eating can lower glucose. The ADA notes that insulin and other diabetes medicines may need adjusting to prevent low blood sugar on very-low-carb eating plans, and it advises regular medical follow-up for people with diabetes who eat this way.
- Usual adult range
- 70–99 mg/dL
Hemoglobin A1c (HbA1c)
The ADA says reviews found carbohydrate-restricted eating lowered A1c in the short term, under 6 months, with less difference after a year. In one 12-week trial, a keto pattern didn't clearly improve A1c and raised LDL compared with a low-carb Mediterranean pattern.
- Usual adult range
- 4.8–5.6 %
Beta-Hydroxybutyrate (BHB)
BHB is a ketone, and the ADA names it as the one to measure in blood. MedlinePlus notes that ketones run higher on a keto diet, usually not high enough to cause ketoacidosis, which makes the blood too acidic. The ADA says very-low-carb eating should be avoided by people taking SGLT2 inhibitor medicines because of the risk of ketoacidosis.
Sources: MedlinePlus and American Diabetes Association (2026)
- Usual adult range
- 0.02–0.27 mmol/L
Uric Acid
Uric acid can rise for a while early in a ketogenic diet and in most cases returns to its earlier level, a 2023 review notes. Across 6 trials lasting 8 to 16 weeks, the average uric acid did not change significantly.
Source: Scientific Reports (2023)
- Men, 18+
- 3.8–8.4 mg/dL
- Women, 18–50
- 2.6–6.2 mg/dL
Ranges shown are the usual adult ranges labs print. The range on your own report is the one your result is judged against.
Getting results you can compare
- Note the date you changed how you eat. Uric acid can run higher early in a keto diet than later on, so the timing of a test changes what it shows.
Source: Scientific Reports (2023)
- Diet changes creatinine, the number eGFR is worked out from. KDIGO lists keto and high-protein diets among things that shift creatinine apart from kidney function, so mention your diet when kidney results are read.
Good to know
- Long-term evidence is thin. The NLA found little data on safety or benefit beyond 2 years, and none of the trials in one large meta-analysis measured heart disease or deaths.
Sources: National Lipid Association (2019) and Nutrients (2020)
- Researchers are still working out what a large LDL rise on low-carb eating means. In the online survey, the largest rises tended to happen in people whose other heart and metabolic markers looked healthy, but its authors say higher heart risk can't be ruled out. The UK Biobank study linked low-carb, high-fat eating with more heart events, but diet was self-reported and the study was observational. Neither kind of study can prove cause.
Sources: Current Developments in Nutrition (2022) and JACC: Advances (2024)
- The ADA notes that very-low-carb eating plans aren't currently recommended during pregnancy or breastfeeding, for children, for people with kidney disease, or for people with or at risk of disordered eating.
Questions you could ask
- How has my LDL changed since I started eating this way, and what does that mean for me?
- Would an ApoB test help us read my cholesterol on this diet?
- When would be a good time to recheck my lipids?
- Do any of my medicines need a closer look while I eat this way?
- Would checking my ketone level tell us anything useful?
Sources
- Review of current evidence and clinical recommendations on the effects of low-carbohydrate and very-low-carbohydrate (including ketogenic) diets for the management of body weight and other cardiometabolic risk factors: A scientific statement from the National Lipid Association Nutrition and Lifestyle Task Force, National Lipid Association (2019)
- The Effect of Low-Fat and Low-Carbohydrate Diets on Weight Loss and Lipid Levels: A Systematic Review and Meta-Analysis, Nutrients (2020)
- Elevated LDL Cholesterol with a Carbohydrate-Restricted Diet: Evidence for a "Lean Mass Hyper-Responder" Phenotype, Current Developments in Nutrition (2022)
- Association of a Low-Carbohydrate High-Fat Diet With Plasma Lipid Levels and Cardiovascular Risk, JACC: Advances (2024)
- The effect of dietary approaches to stop hypertension and ketogenic diets intervention on serum uric acid concentration: a systematic review and meta-analysis of randomized controlled trials, Scientific Reports (2023)
- 5. Facilitating Positive Health Behaviors and Well-being to Improve Health Outcomes: Standards of Care in Diabetes-2026, American Diabetes Association (2026)
- Ketones in Blood, MedlinePlus
- KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease, Kidney Disease: Improving Global Outcomes (2024)
AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-19. How we build and check these pages.
Educational information, not medical advice. Blood Test Tracker doesn’t diagnose or treat, and it doesn’t replace your clinician. Talk with your clinician before changing medications, supplements or care.