The world of weight-loss diets is constantly evolving, with low-carbohydrate, high-protein eating plans frequently capturing public attention. Among these, the ketogenic, or "keto," diet has gained significant popularity. A true ketogenic diet differs from other low-carb diets, such as the Paleo, South Beach, and Atkins diets, in that it centers on fat as the primary source of calories, sometimes supplying as much as 90% of daily calories. The carnivore diet, a more extreme version of keto, further restricts food intake, focusing almost exclusively on animal products. This article explores the potential benefits and risks associated with the keto meat diet, also known as the carnivore diet.
What is the Carnivore Diet?
The carnivore diet meal plan permits the intake of only meat, poultry, eggs, seafood, fish, some dairy products, and water. It excludes all vegetables, fruits, grains, legumes, seeds, and nuts. The carnivore diet is a type of "keto," or ketogenic, diet.
How Keto Diets Work
Keto diets work by restricting carbohydrate intake, which deprives the body of its primary energy source, glucose. In response, the body begins to burn fat, producing ketones as an alternative fuel source. The carnivore diet is considered the most ketogenic diet because it allows for almost no carbs.
Roshini G. Merneedi, RD, a dietitian at Northwestern Medicine, explains that your body's primary energy source is glucose, which comes from the breakdown of carbohydrates. When these stores are full, they are converted into fat. The keto diet limits carbohydrates, forcing your body to burn fat for fuel instead. In this state, your body breaks down fats into molecules called ketones, which serve as an alternative fuel source.
Types of Ketogenic Diets
There are several different styles of keto diets:
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- Standard Ketogenic Diet (SKD): This is a very low carb, moderate protein, and high fat diet. It typically contains 70% fat, 20% protein, and only 10% carbs (9).
- Cyclical Ketogenic Diet (CKD): This diet involves periods of higher carb refeeds, such as 5 ketogenic days followed by 2 high carb days.
- Targeted Ketogenic Diet (TKD): This diet allows you to add carbs around workouts.
- High Protein Ketogenic Diet: This is similar to a standard ketogenic diet, but includes more protein. The ratio is often 60% fat, 35% protein, and 5% carbs.
However, only the standard and high protein ketogenic diets have been studied extensively. Cyclical or targeted ketogenic diets are more advanced methods and primarily used by bodybuilders or athletes.
Potential Benefits of Keto Diets
Weight Loss
Because keto diets induce the body to burn fat, all keto diets can jump-start a weight-loss program. Research suggests that the keto diet helps people cut calories because the diet doesn't include many foods that people are likely to overeat. On paper, burning fats by eating more of them is enticing, which is why the keto diet has become popular. The keto diet allows many people to eat the types of high-fat foods that they enjoy, such as red meats, fatty fish, nuts, cheese and butter, while still losing weight.
One review of 13 studies found that following a very low carb, ketogenic diet was slightly more effective for long-term weight loss than a low fat diet. People who followed the keto diet lost an average of 2 pounds (0.9 kg) more than the group that followed a low fat diet (13).Another study in 34 older adults found that those who followed a ketogenic diet for 8 weeks lost nearly five times as much total body fat as those who followed a low fat diet (17).
Reduced Seizures in Children with Epilepsy
There is evidence that the keto diet can help specific groups of people. The keto diet helps reduce seizures in children with epilepsy. The keto diet was first used as a treatment for pediatric drug-resistant epilepsy to reduce seizures in the 1920s. when medications alone aren't enough. The keto diet is primarily used to manage seizures in children with epilepsy.
Other Potential Benefits
The keto diet is being studied for reducing symptoms for patients with progressive neurological disorders like Parkinson’s disease. Studies have now shown that the diet can have benefits for a wide variety of different health conditions:
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- Heart disease. The ketogenic diet can help improve risk factors like body fat, HDL (good) cholesterol levels, blood pressure, and blood sugar (28, 29).
- Cancer. The diet is currently being explored as an additional treatment for cancer, because it may help slow tumor growth. (4, 30, 31).
- Alzheimer’s disease. The keto diet may help reduce symptoms of Alzheimer’s disease and slow its progression (5, 32, 33).
- Parkinson’s disease. Although more research is needed, one study found that the diet helped improve symptoms of Parkinson’s disease (34).
- Polycystic ovary syndrome. The ketogenic diet can help reduce insulin levels, which may play a key role in polycystic ovary syndrome (35, 36).
- Brain injuries. Some research suggests that the diet could improve outcomes of traumatic brain injuries (37).
However, scientific research has not confirmed benefits for these patients, Dr. Ring says, and more research is needed before it can be widely recommended. Keep in mind that research into many of these areas is far from conclusive.
Risks and Concerns
Elevated Cholesterol Levels
While some keto diets can emphasize the intake of healthier mono- and polyunsaturated fats, that's not the case with carnivore diets. The disadvantage of all keto diets is they tend to raise LDL cholesterol levels in both the short and long term. “We know that higher cholesterol tends to increase your chances of heart attacks and strokes,” says Dr. Cheema.
Kidney Problems
Other longer-term concerns about keto diets, especially the carnivore diet, include the increased risk of kidney stones, gout, and osteoporosis. The keto diet may not be appropriate for everyone, specifically people with kidney disease. Consuming a large amount of animal protein can lead to unwanted stress on the kidneys, especially if you already experience kidney issues. “Although more research is needed in that area, there is some suggestion that it can make kidney disease worse over time,” says Dr. Some people also experience dehydration on the keto diet because they’re eliminating glycogen, which holds water, from the bloodstream.
Nutrient Deficiencies
“Because the keto diet is so restricted, you’re not receiving the nutrients - vitamins, minerals, fibers - that you get from fresh fruits, legumes, vegetables and whole grains,” says Dr. Ring. By excluding all plant-based foods, the carnivore diet increases the risk of nutritional deficiencies, including vitamins C, E and K, folate and magnesium. The keto diet is very low in carbs which means you can't eat many fruits and vegetables.
Heart Health
The high-fat nature of the diet could also have negative impacts on heart health. The American Heart Association recommends limiting saturated fat intake to less than 6%. “In practice, many people eat high amounts of saturated fats, which could increase your risk of heart disease,” says Dr. Cheema. “You may be eating a lot of fatty meat thinking it’s a good thing for you because it's high in fat. This can dramatically alter your lipid profile. While high-fat diets can elevate LDL (“bad”) cholesterol, the type of saturated fat matters. The bottom line is that having more fats in your diet can lead to higher cholesterol. Extreme diets high in saturated fat and low in fibre are known to raise cholesterol levels, increasing the risk of heart attack and stroke. One of the main issues is that it’s high in saturated fats due to its high amounts of red meat and dairy. Too much saturated fat can increase levels of bad cholesterol (known as non-HDL cholesterol) in the blood. Both high cholesterol and high blood pressure raise the risk of developing coronary heart disease and having a heart attack or stroke.
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Digestive Problems
A strict carnivore diet lacks dietary fiber which can lead to constipation or diarrhea, gas, bloating and an increased risk of colon cancer. Constipation is likely the greatest long-term complication of the keto diet because of a low fiber intake. Fiber is a form of carb that is digested not by our human cells, but by the microbes in our gut. Any high-fiber foods (like beans, whole grains, and certain fruits) are also high in carbs, which is not typically part of the keto diet.
Psychological Effects
When you micromanage your food intake by tracking how much you eat, it disconnects you from what your body is asking for. You start using outside numbers to determine what to eat instead of listening to your body. “Being intuitive and understanding what your body needs is essential for proper nourishment,” says Merneedi. Monitoring food so closely can lead to psychological distress, such as shame and binge eating. Strict diets like keto could also cause social isolation or disordered eating.
Other Side Effects
People report feeling foggy, irritable, nauseous and tired. “In particular, low fiber intake can disrupt gut microbiota and lead to chronic constipation, while inadequate magnesium, vitamin C and potassium can contribute to muscle cramps, fatigue and weakened immune function,” explains Dr. The keto diet can cause your blood pressure to drop in the short term due to a reduction in blood volume and changes in your fluid balance. Symptoms of low blood pressure include dizziness, lightheadedness or fainting, especially when standing up quickly. Following a keto diet can also cause your blood sugar to drop, which can be dangerous for people living with diabetes. Common symptoms of low blood sugar include weakness or shaking, sweating, a fast heartbeat and dizziness. Also, when people start the keto diet, they go through the keto flu. Keto flu symptoms appear a few days after starting the diet. This eventually goes away once your body adjusts to your eating changes.
Sustainability
Because of the stringent food restrictions, many find the keto diet hard to stick to. “The ketogenic diet can be effective for weight loss when used in a short time period followed by the adoption of healthier eating habits,” says Baljash Singh Cheema, MD, a cardiologist at Northwestern Medicine Bluhm Cardiovascular Institute. “However, we know in studies of these types of diets that once people stop following that diet, they regain at least half of the weight that they lost. Ketosis is difficult to achieve because it’s like a light switch: either on or off. Individuals who consistently track food intake are more likely to remain in ketosis. “The best diet is the one you can sustain the longest. A gradual lifestyle change approach is more manageable than tackling a trendy diet that is drastically different than your usual diet.
Who Should Avoid the Carnivore Diet?
People with a history of heart disease, kidney issues or nutrient deficiencies should approach the carnivore diet with caution. Anyone taking this medication should avoid the keto diet (40, 41).
Alternatives to the Carnivore Diet
For long-term weight loss, Dr. Ring, Dr. Intermittent fasting is an approach that allows you to receive the benefits of ketosis while still eating a varied and balanced diet, says Dr. Ring. By cycling between periods of eating and fasting, your body enters “mild ketosis” during the fasting phase. “Unlike the keto diet, which requires strict food restrictions, intermittent fasting lets you enjoy a variety of nutrient-dense foods, such as fruits, vegetables, whole grains and legumes, during eating windows,” Dr. Ring explains.
Dr. Cheema advocates making small changes based on your health goals. “People tend to burn out on those big goals and challenges, and then they go back into their own habits,” he explains. “Just because you were super fit between the ages of 36 and 38 may not extend your healthy life. But if you make small changes consistently every day from ages 36 to 66, that probably will have a big impact. No one diet fits all, and what works for one person may not work for another.