Mixed Views on Short-Term vs. Long-Term Effects
Heart doctors often view the keto diet with a mix of cautious optimism and significant reservations, largely differentiating between short-term outcomes and potential long-term risks. For some patients, particularly those with obesity and type 2 diabetes, a ketogenic diet can offer rapid improvements. These benefits include quick weight loss, better blood sugar regulation, and reduced blood pressure. A recent study found that a low-carbohydrate, high-fat diet could potentially lead to a reduction in triglycerides and an increase in HDL ("good") cholesterol.
However, cardiologists emphasize that these short-term gains do not tell the full story. The very nature of the diet, which requires high fat intake, can pose substantial risks, especially when those fats come from unhealthy sources. The long-term effects on cardiovascular health are not well-understood, and recent studies suggest potential negative correlations.
The Problem with LDL Cholesterol and Saturated Fats
One of the most persistent red flags raised by heart doctors is the effect of the keto diet on cholesterol levels, particularly LDL cholesterol. While some people may experience improved lipid profiles, many see a significant and concerning increase in their LDL cholesterol.
- Higher Saturated Fat Intake: A strict keto diet often involves consuming a large amount of fats from sources like red meat, butter, and cream. These saturated fats are known to increase artery-clogging LDL cholesterol, which can lead to atherosclerosis and an increased risk of heart attacks and strokes.
- Cardiovascular Events: A study presented at the American College of Cardiology's Scientific Session linked a "keto-like" diet to higher LDL cholesterol and a two-fold heightened risk of cardiovascular events.
- Long-Term Concerns: High cholesterol levels that persist over months or years are particularly worrisome for heart health. This is why cardiologists often recommend regular monitoring for patients who choose to follow the diet.
The Role of Whole Foods and Fiber
Cardiologists also point out that the restrictive nature of the keto diet can lead to nutritional deficiencies. By eliminating whole grains, fruits, and many vegetables, individuals miss out on key nutrients and dietary fiber that are protective for the heart.
- Whole foods high in fiber, such as fruits, vegetables, and legumes, help lower cholesterol and regulate blood sugar.
- These foods also provide anti-inflammatory benefits that support long-term heart health.
- The keto diet's emphasis on high fat can sideline these critical sources of nutrition.
Comparing Keto to Other Heart-Healthy Diets
Heart doctors frequently advocate for more balanced, sustainable dietary patterns. They often cite the Mediterranean diet as a preferable alternative for long-term heart health.
| Feature | Ketogenic Diet | Mediterranean Diet |
|---|---|---|
| Macronutrient Balance | Very high fat (60-80%), moderate protein, very low carbohydrate (<10%) | High in healthy fats (from olive oil, nuts), moderate protein (mostly fish/poultry), moderate-to-high carbohydrate (from fruits, vegetables, whole grains) |
| Primary Energy Source | Fats (leading to ketosis) | Carbohydrates from whole foods |
| Impact on LDL Cholesterol | Variable, often increases | Shown to lower LDL cholesterol |
| Saturated Fat Intake | Typically higher from meats and dairy | Low, emphasizes healthier monounsaturated and polyunsaturated fats |
| Dietary Fiber | Often very low due to restricted fruits, grains, and legumes | High, emphasizes fruits, vegetables, whole grains, and legumes |
| Sustainability | Difficult for many to maintain long-term | Highly sustainable lifestyle |
| Medical Consensus | Cautious, citing unknown long-term risks | Widely endorsed for heart health |
Conclusion: A Cautious and Individualized Approach
Ultimately, the cardiologist's take on the keto diet is not a simple yes or no. They acknowledge the potential for short-term benefits, such as weight loss and improved metabolic markers, which can indirectly help heart health. However, they stress that these benefits must be weighed against the significant risks, particularly the potential for elevated LDL cholesterol and the lack of long-term safety data.
Experts like Dr. Neel Chokshi at Penn Medicine recommend against extremes for extended periods, favoring instead sustainable lifestyle changes. For individuals with a history of heart disease, high cholesterol, or diabetes, cardiologists strongly urge caution and close medical supervision. A better approach, they suggest, is a balanced diet rich in whole foods, like the Mediterranean diet, coupled with regular exercise, for long-term cardiovascular well-being. For more information on dietary recommendations, see the guidance from HEART UK: https://www.heartuk.org.uk/news-and-blogs/ketogenic-diets.
Who Should Avoid the Keto Diet?
Certain individuals should exercise extreme caution or completely avoid the keto diet based on cardiologists' advice.
- Those with existing high cholesterol or heart disease.
- People with a history of heart attacks, strokes, or related cardiovascular events.
- Patients on blood-thinning medications like warfarin, as the diet's low carb, high leafy-green content could interfere.
- Individuals with pre-existing kidney or liver disease.
- Anyone with an eating disorder.
The Importance of Medical Supervision
If an individual still wants to pursue a ketogenic diet, consulting with a healthcare provider is paramount. This includes monitoring cholesterol levels regularly and addressing other risk factors. Cardiologists stress that the long-term effects of sustained ketosis on the body are not fully known, making professional medical guidance a necessity.
