Keto, Carnivore and Cholesterol: What Happens to Your Numbers (and What to Ask Your Doctor)

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“Aren’t you worried about your cholesterol?” If you eat this way, someone has asked you this. Probably at a family dinner. Probably while you were eating bacon.

It’s a fair question, and heart disease runs in my family: my biological father had a quadruple bypass in his forties. So I don’t brush this one off. Here’s what the research shows and what I do about it.

The numbers on a cholesterol test

A standard lipid panel usually shows four numbers (the American Heart Association has a good plain-English guide):

• LDL, often called “bad” cholesterol. High LDL is linked with plaque buildup in arteries.
• HDL, often called “good” cholesterol. It helps carry cholesterol away.
• Triglycerides, a type of fat in your blood. High levels are linked with heart disease and often go along with high blood sugar and insulin.
• Total cholesterol, the overall number.

What usually happens on keto

A review comparing low-carb and low-fat diets found that low-carb diets led to lower triglycerides and higher HDL, which are both good signs. But they also led to higher LDL on average (Mansoor et al., 2016).

The average hides big differences between people. In one small trial, healthy normal-weight young adults ate a strict low-carb, high-fat diet for 3 weeks. Their LDL rose by about 44% on average, and some people’s rose far more than others’ (Retterstøl et al., 2018). Lean, active people seem more likely to see big LDL jumps.

What about carnivore?

There are no clinical trials yet. The biggest look we have is a 2021 survey of 2,029 adults eating carnivore. Most reported feeling healthier. On their reported labs, HDL tended to be high and triglycerides low, but LDL was often high (Lennerz et al., 2021). That’s self-reported data from enthusiastic people, so take it as a clue, not proof.

Is high LDL on keto dangerous?

Honestly, nobody knows for sure yet. Some researchers think high LDL matters less when triglycerides are low, HDL is high and blood sugar is healthy. Most cardiologists still treat high LDL as a risk no matter what diet caused it. There aren’t long-term studies to settle it.

So I won’t tell you it’s fine, and I won’t tell you to panic. This is exactly the kind of decision to make with your doctor, using your numbers and your family history.

What I recommend

• Get bloodwork. Before keto, my doctors winced at my numbers. Later they asked if I was running marathons. I only know that because I tested.
• Keep the basics simple: real meat, fish and eggs, and skip the processed “keto” junk food.
• Watch the trend, not one test. One number on one day doesn’t tell the whole story.

Labs to ask your doctor about

• Lipid panel (LDL, HDL, triglycerides): before you start and around 3 months in.
• Fasting glucose and A1c, for blood sugar.
• ApoB or LDL particle number, if your LDL comes back high. Some doctors find these more helpful than LDL alone.
• Coronary artery calcium (CAC) scan, if your doctor thinks it makes sense for your age and family history.

If you have a family history of very high cholesterol or early heart disease, or you already have heart disease, talk with your doctor before you start.

Frequently asked questions

Does keto raise cholesterol?

It often raises HDL and lowers triglycerides. LDL rises for some people, sometimes a lot, and stays about the same for others. Bloodwork is the only way to know what it does for you.

How long after starting keto should I check my cholesterol?

Many people test before starting and again after about 3 months, once the first big changes settle. Ask your doctor what timing makes sense for you.

Is carnivore bad for your heart?

We don’t know yet. There are no long-term trials. Surveys show high HDL and low triglycerides but often high LDL. Work with your doctor and check your numbers.

Can I lower LDL and still eat low-carb?

Some people lower it by leaning on leaner meats, fish, eggs and olive oil and cutting back on butter and cream. Your doctor may also suggest other options. Recheck after any change.

Your next step

• 8 things to track when you start keto (bloodwork is one)
• Benefits of keto: what research actually supports
• Carnivore diet for beginners

Sources

• American Heart Association. About Cholesterol.
• Mansoor N, et al. Effects of low-carbohydrate diets v. low-fat diets on body weight and cardiovascular risk factors: a meta-analysis of randomised controlled trials. British Journal of Nutrition. 2016.
• Retterstøl K, et al. Effect of low carbohydrate high fat diet on LDL cholesterol and gene expression in normal-weight, young adults: A randomized controlled study. Atherosclerosis. 2018.
• Lennerz BS, et al. Behavioral Characteristics and Self-Reported Health Status among 2029 Adults Consuming a “Carnivore Diet”. Current Developments in Nutrition. 2021.

I’m a mom sharing my experience, not a doctor, and this isn’t medical advice. Please talk with your doctor before changing how you eat, especially if you have heart disease, high cholesterol, a family history of early heart disease, or take medication.