For millions of people adhering to the keto diet, fat is not the enemy; it’s the main component of their meals.
This low-carb, high-fat diet was initially developed in the 1920s to treat children with epilepsy. Over the decades, it has gained popularity in the wellness community, attracting yoga enthusiasts, gym-goers, and weight-loss seekers alike.
By 2024, the ketogenic market is projected to be worth £9.2 billion ($12.5 billion) and continues to experience exponential growth.
The fundamental premise of the keto diet is to utilize fat as the primary energy source. This contrasts sharply with conventional diets primarily reliant on glucose, the simple sugar produced by the breakdown of carbohydrates.
On a ketogenic diet, individuals consume a minimal amount of carbohydrates, resulting in reduced glucose production. Instead, approximately 80% of caloric intake comes from fat, which the liver converts into an alternative energy source known as ketones—hence the term “ketogenic.”
Keto enthusiasts often report weight loss without the pangs of hunger. They claim it enhances energy levels, mental focus, and clarity. Additionally, this diet is believed to reduce inflammation, stabilize blood sugar levels, decrease the risk of type 2 diabetes, and improve skin conditions.
While these benefits sound enticing, there are caveats. Consuming high levels of fat daily can lead to side effects, notably elevated cholesterol levels in some individuals following the ketogenic diet.
“Many [keto dieters] consume such high amounts of saturated fat that while they may see positive changes such as weight loss, their cholesterol levels could skyrocket,” warns Professor Kosh Ray, a leading cardiologist at Imperial College London.
“If I didn’t know they were eating this way, I would suspect a genetic disorder affecting cholesterol metabolism.”
This cholesterol issue often arises in those claiming to have lost weight and feel fantastic on a keto diet. So, the pressing question is: should individuals on a keto diet who appear healthy on the outside—with their cholesterol levels soaring—be concerned about their heart health?
Why Medical Professionals Are Concerned
For most cardiologists, the connection between LDL cholesterol (the “bad” cholesterol) and heart disease risk is clear.
“Numerous studies indicate that lower LDL cholesterol levels correlate with a reduced risk of cardiovascular disease,” explains Ray.
To grasp the significance of LDL, it helps to understand its function. Cholesterol acts as a fatty substance necessary for bodily functions, akin to a taxi transporting proteins to and from the liver through the bloodstream.
LDL carries cholesterol away from the liver, whereas HDL returns it. A proper balance between the two is crucial for effective cholesterol transport.
However, LDL can adhere to artery walls and become problematic, particularly when the wall is damaged (due to age, smoking, or inflammation).
This can result in a condition known as plaque buildup, which hardens over time. If this plaque ruptures, it can obstruct blood flow and lead to a heart attack.
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Lean Mass Hyper Responder Theory
Conventional views suggest that high LDL cholesterol among keto dieters indicates an increased heart disease risk. But some self-proclaimed “citizen scientists” argue otherwise.
They believe high cholesterol levels may not pose a threat on a keto diet.
Some even assert that levels exceeding the standard healthy limit (100 mg/dL or 2.6 mmol/L) are permissible, suggesting that dietary fat protects heart health.
This term is often referred to as lean mass hyper responder—a classification that most medical experts question.
“The term ‘lean mass hyper responder’ lacks medical validation,” cautions Dr. Scott Murray of the Venturi Cardiology Clinic.
This term originated from a computer scientist who explored the cholesterol spikes in keto dieters and sought to understand them.
Although the idea is novel, it lacks substantial scientific support. This group has initiated studies to analyze high-cholesterol keto dieters better.
Their initial findings linked spikes in LDL cholesterol to thinness among participants, suggesting that such cholesterol levels might not be harmful for “hyperresponders.”
“The theory suggests that increased dependence on fat as an energy source leads to higher fat transport,” explains nutritional therapist Moira Newis, a self-identified hyperresponder.
If you are metabolically healthy, transporting more fat within the body might not be a concern.
Proponents also point to the anti-inflammatory properties of a ketogenic diet. Since both high cholesterol and inflammation contribute to plaque formation, the idea is that reducing inflammation could render cholesterol benign.
However, inflammation levels vary among individuals, and it’s impossible to eliminate it entirely, regardless of dietary choices.
Currently, there’s no evidence supporting the notion that excess cholesterol is beneficial on a keto diet.
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The Keto Controversy
In an effort to substantiate their claims, citizen scientists published a paper in April 2025 arguing that hyperresponders on keto diets face no increased heart disease risk, countering established cardiologist viewpoints.
However, the scientific community is taking a firm stance against these claims.
This study analyzed arterial plaque in 100 hyperresponders over one year, finding that those with elevated LDL cholesterol levels showed no significant plaque development compared to those with lower yet still high cholesterol levels.
“LDL levels alone do not predict heart risk accurately,” states Dr. Adrian Sotomota, the leading author and clinical researcher.
Nonetheless, this study has significant flaws, notably the absence of a control group, making it difficult to compare results against normal diets with healthy cholesterol levels.
Among the 100 hyperresponders studied, 99 experienced plaque worsening.
Sotomota explains that plaque progression is common and can be influenced by various factors, including blood pressure and diet, not solely cholesterol levels.
Professor Ray criticizes the study’s findings, stating they contradict established scientific principles and asserting that the prevalence of plaque growth is much higher than observed in typical healthy populations, pointing to an increased heart attack risk.
Current Evidence on Cholesterol and the Keto Diet
While much remains unclear about cholesterol and the ketogenic diet, current evidence suggests that high LDL cholesterol levels are a significant risk factor for heart disease, not just for hyperresponders but for all.
Dr. Murray recommends CT scans for patients on a keto diet exhibiting very high LDL cholesterol to assess arterial plaque.
If their results show healthy arteries, he suggests modifications to their diet, integrating healthy carbohydrates and lowering saturated fat and cholesterol intake.
If plaque or advanced coronary artery disease is detected, he insists on dietary changes and medication to manage plaque regression.
Murray emphasizes the risks associated with extreme dietary practices, warning against being excessively lean while only consuming fats and proteins.
“The body thrives on balance, and existing in the extremes of a keto diet doesn’t serve health in the long run,” he highlights.
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Source: www.sciencefocus.com
