- New research finds that following a low-carbohydrate diet can raise cholesterol levels.
- Cholesterol is more likely to increase on a low-carb diet in people with certain genes.
- The findings could dictate how high cholesterol is treated in the future.
When trying to lose weight and improve their health, many people choose to try a low-carb diet. But new research suggests this diet could cause cholesterol levels to rise in some people.
The study, which was presented at the American Society for Nutrition’s annual meeting, analyzed data from DIETFITS—a randomized, controlled trial that tracked more than 600 adults for a year as they followed either a healthy low-carb diet or healthy low-fat diet. The researchers also looked at participants’ genes, how much saturated fat they ate, and their levels of LDL (“bad”) cholesterol at the start of the study and six months later.
After crunching the numbers, the researchers found that participants with a genetic predisposition to elevated LDL cholesterol were more likely to see their cholesterol go up while following the low-carb diet. “In contrast, participants with a lower genetic predisposition had, on average, a less pronounced LDL cholesterol response,” says Alexa Barad, Ph.D., R.D.N., study co-author and a postdoctoral scholar at Stanford University School of Medicine. (The researchers didn’t see the same correlation in people who followed the low-fat diet.)
If you’re on a low-carb diet, it’s fair to wonder if you may be unintentionally putting your health at risk, as high cholesterol is linked with a higher risk of developing cardiovascular complications, including heart attack and stroke. Here’s what experts want you to keep in mind.
Meet the experts: Jessica Cording, R.D., author of The Little Book of Game-Changers; Juli MacKenna, R.D., clinical nutrition manager at MelroseWakefield Hospital; Alexa Barad, Ph.D., R.D.N., study co-author and a postdoctoral scholar at Stanford University School of Medicine; Janet M. O’Mahony, M.D., an internal medicine doctor at Mercy Medical Center; Joseph Daibes, D.O., an interventional cardiologist at Northwell’s Lenox Hill Hospital in New York City; Cheng-Han Chen, M.D., an interventional cardiologist and medical director of the Structural Heart Program at MemorialCare Saddleback Medical Center.
What might a low-carb diet raise your cholesterol?
There are likely a few things happening here.
Low-carb diets tend to replace calories that would have come from carbohydrates with fat, so it’s important to be mindful of what kinds of fat you’re ingesting, says Juli MacKenna, R.D., clinical nutrition manager at MelroseWakefield Hospital. If you end up eating a lot of saturated fat, that can raise your LDL cholesterol levels.
MacKenna adds that people with less body fat more commonly experience high increases in LDL cholesterol while following a low-carb diet. Restricting carbs drains stores of glycogen (the stored form of glucose or sugar that the body uses for energy) in the liver, she explains. That sparks the release of adipocyte free fatty acids, a type of fat that can raise LDL cholesterol, MacKenna says.
How can you tell if your cholesterol is tied to genetics?
It’s possible to develop high LDL cholesterol from diet and lifestyle factors, but genetics can “absolutely” be a factor in cholesterol levels, Cording says. “I’ve had clients who say, ‘I don’t understand. I don’t eat red meat, eggs, or whole-fat dairy. I exercise. What’s going on?’” she says. “If you feel like you’re following all of the lifestyle recommendations and your LDL is still high, that could be a clue that your genetics are an influence.” MacKenna agrees: “If your cholesterol levels are elevated despite following a diet that is low in animal protein and saturated fat, there are likely genetic factors at play that are outside your control,” she says.
This is more common than most people realize. Joseph Daibes, D.O., an interventional cardiologist at Northwell’s Lenox Hill Hospital in New York City, says he frequently sees patients who “are doing everything right, and they still have high cholesterol.”
Still, Cording cautions, it’s important not to assume that genetics are to blame before looking into lifestyle factors. “There are other things that can influence cholesterol levels by way of influencing how efficient our liver is at processing fat,” she says. Cording notes that stress and lack of sleep can also affect cholesterol, although more research is needed to confirm this link.
What will healthcare providers do?
If your LDL cholesterol levels are high, your healthcare provider will likely recommend making lifestyle changes first. “Lifestyle modification is always the first step and the basis for everything else,” says Cheng-Han Chen, M.D., an interventional cardiologist and medical director of the Structural Heart Program at MemorialCare Saddleback Medical Center in Laguna Hills, California.
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The American Heart Association (AHA) recommends these strategies:
- Eat a diet rich in vegetables, fruits, whole grains, beans, nuts, seeds, unsaturated fats, and lean proteins.
- Limit ultra-processed foods that are high in saturated fats, added sugars, and sodium.
- Try to maintain a healthy weight.
- Get regular physical activity.
- Aim to get seven to nine hours of sleep a night.
If you’re unsure about how to create a cholesterol-friendly diet, your healthcare provider will likely refer you to a registered dietitian who can help you come up with an eating plan that’s low in saturated fat, MacKenna says.
After recommending changes to diet and lifestyle, your healthcare provider will typically suggest sticking with these new habits for a few months before having your levels checked again. “Most doctors will re-test you in three to six months,” Cording says.
If things still haven’t improved by that point, your doctor will likely recommend medication, says Dr. Daibes. “We are much more aggressive [with drugs] these days because we know that intervention and treatment of high cholesterol will prevent heart attacks and strokes from happening later on in life,” he says.
Statins are a common option, says Janet M. O’Mahony, M.D., an internal medicine doctor at Mercy Medical Center in Baltimore. “These drugs are preferred first-line for people at high risk of heart disease and stroke,” she says. “If statins are not enough, or if a patient does not tolerate a statin drug, there is another class of drug, PCSK-9 inhibitors, which are appropriate for certain high-risk individuals.”
Still, your healthcare provider will typically recommend maintaining a healthy diet and lifestyle even after starting medication, Dr. Chen says. “You don’t get on medicine and then forget to follow a healthy diet,” he says.
How to navigate a low-carb diet if you’re predisposed to high cholesterol
It’s still possible to follow a low-carb diet if high cholesterol is in your genes, Dr. Daibes says. “Having a low-carb diet itself is not what causes your cholesterol to go up,” he says.
Cording suggests focusing on fiber. Soluble fiber binds to fats, which your body then flushes out as waste. This can lower cholesterol, Cording says.
Luckily, Cording says you can still get plenty of fiber from low-carb foods. She suggests focusing on options like avocado, chia seeds, and berries. “There are so many ways to get fiber that aren’t also high in carbohydrates,” she says.
Cording also suggests limiting fattier meats like beef, lamb, and pork, along with processed meats. Most people can have full-fat dairy, though, as long as it’s in moderation and part of an overall healthy eating pattern.
The bottom line
Thanks to research in this vein, genetic testing may one day be used to determine each patient’s cholesterol management plan. Cording is excited for this possibility. “Genetics can be really important when it comes to cholesterol management,” she says.
However, while this recent study highlights the importance of genetics, Barad says diet still matters. “In fact, our findings suggest that diet may be especially important for these individuals, as those with a higher genetic predisposition experienced larger increases in LDL cholesterol when saturated fat intake increased on a low-carbohydrate diet,” she says.
Additionally, Barad says the findings underscore the importance of continual cholesterol testing, even after people change their habits. “Our findings highlight the importance of monitoring LDL cholesterol after major dietary changes, particularly when adopting a low-carbohydrate diet,” she says. “At the same time, our results reinforce current dietary guidance to limit saturated fat intake.”
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