The world of weight-loss diets is filled with options, each with its own set of principles and purported benefits. Among the popular choices are high-protein and ketogenic (keto) diets. Both diets have gained traction for their potential to promote weight loss and improve certain health markers. However, they differ significantly in their macronutrient composition, mechanisms of action, and potential health effects. This article provides a comprehensive comparison of high-protein and keto diets to help you make an informed decision about which one might be right for you.
Understanding the Basics
High-Protein, Low-Carb Diets
A high-protein, low-carb diet involves reducing carbohydrate intake and increasing protein consumption. There isn't a strict macronutrient ratio, but it generally entails limiting carbs to less than 26% of daily calories and consuming more protein than the Recommended Daily Allowance (RDA) of 0.8 grams per kilogram of body weight. Some high-protein diets may include up to 2 grams of protein per kilogram of body weight. To compensate for the carb deficit, fat intake may be increased.
Ketogenic (Keto) Diets
The ketogenic, or keto, diet is a high-fat, very low-carbohydrate diet designed to induce a metabolic state called ketosis. In ketosis, the body switches from using glucose (sugar) as its primary fuel source to using ketones, which are produced from stored fat. This is achieved by drastically reducing carbohydrate intake, typically to less than 50 grams per day, and increasing fat consumption to 70-80% of total daily calories. Protein intake is moderate, usually around 10-20% of calories.
How They Work
High-Protein, Low-Carb Diets
High-protein, low-carb diets promote weight loss through several mechanisms:
- Increased Satiety: Protein is more satiating than carbohydrates or fats, helping you feel full and satisfied after meals, which can lead to reduced calorie intake.
- Reduced Hunger and Cravings: High-protein diets can lower levels of hunger hormones like ghrelin and increase levels of fullness hormones like glucagon, cholecystokinin, and peptide YY.
- Boosted Metabolism: Protein has a higher thermic effect of food (TEF) compared to carbs and fats, meaning your body burns more calories digesting protein. Additionally, high protein intake can help preserve lean muscle mass during weight loss, which can help maintain a higher basal metabolic rate.
Ketogenic (Keto) Diets
The keto diet works by:
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- Inducing Ketosis: By severely restricting carbohydrate intake, the body is forced to break down stored fat into ketones, which become the primary fuel source.
- Appetite Suppression: Ketones may have an appetite-suppressing effect, potentially reducing hunger and calorie intake.
- Weight Loss: When the body burns fat for fuel, it can lead to weight loss, especially in the initial stages of the diet.
Comparing Macronutrient Ratios
| Macronutrient | High-Protein, Low-Carb Diet | Ketogenic (Keto) Diet |
|---|---|---|
| Protein | 30-40% | 10-20% |
| Carbohydrates | Less than 26% | 5-10% |
| Fat | 30-40% | 70-80% |
Food Choices
High-Protein, Low-Carb Diet
- Foods to Include:
- Animal protein: eggs, chicken, bison, turkey, beef, lamb, pork
- Plant-based protein: tofu, edamame, and other soy foods
- Fish and shellfish: cod, flounder, clams, shrimp, etc
- Dairy: Greek yogurt, cow’s milk, and cottage cheese
- Non-starchy vegetables: broccoli, cauliflower, greens, peppers, asparagus, mushrooms, etc
- Nuts and seeds: almonds, pumpkin seeds, sunflower seeds, peanut butter, chia seeds, and hemp seeds
- Condiments: fresh herbs, pepper, spices, etc
- Beverages: water, sparkling water, unsweetened herbal tea, unsweetened coffee, etc
- Foods to Limit:
- Grains and starches: breads, rice, pasta, baked goods, cereals, etc
- Sweeteners: sugar, agave, maple syrup, honey, coconut sugar, etc
- Sugary drinks: juice, sweetened coffee and tea, soda, sports drinks, sweetened alcohol beverages, beer, etc
- Processed, high-carb foods: french fries, fried chicken, pizza, chips, etc
Ketogenic (Keto) Diet
- Foods to Include:
- Healthy fats: avocados, olive oil, coconut oil, nuts, and seeds
- Non-starchy vegetables: leafy greens, cauliflower, broccoli, asparagus
- Moderate protein: meat, poultry, fish, eggs
- Some dairy: cheese, heavy cream (in moderation)
- Foods to Avoid:
- Grains: wheat, rice, oats, corn
- Sugary foods: candy, soda, juice, pastries
- Starchy vegetables: potatoes, sweet potatoes, corn, peas
- Most fruits: exceptions include small portions of berries
- Legumes: beans, lentils, chickpeas
Potential Benefits
High-Protein, Low-Carb Diet
- Weight Loss: Research suggests that higher protein consumption may play several key roles in promoting weight loss, such as increasing feelings of fullness, reducing hunger and cravings, lowering levels of hunger hormones, increasing levels of fullness hormones, boosting basal metabolic rate, and increasing the thermic effect of food.
- Improved Body Composition: Eating a high protein, low carb diet may also help improve body composition. Research shows that increasing protein intake while cutting calories can maintain muscle mass while promoting fat loss. High protein diets may help increase muscle mass when combined with resistance training.
- Other Potential Health Benefits: regulating blood sugar (especially important for those with diabetes), reducing bone loss and fracture risk in older adults, reducing the risk of cognitive decline and improving cardiometabolic factors.
Ketogenic (Keto) Diet
- Weight Loss: The ketogenic diet has been shown to produce beneficial metabolic changes in the short-term. Along with weight loss, health parameters associated with carrying excess weight have improved, such as insulin resistance, high blood pressure, and elevated cholesterol and triglycerides.
- Epilepsy Treatment: 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.
- Potential Brain Health Benefits: The keto diet can show positive results for helping the brain. Researchers are looking to see if the keto diet can help treat age-related brain decline and potentially Alzheimer's disease. These include the direct benefit from the presence of ketone bodies, especially one called beta hydroxybutyrate.
Potential Risks and Side Effects
High-Protein, Low-Carb Diet
- Heart Health Concerns: Some research associates high protein, low carb diets with an increased risk of heart disease and heart failure. However, research on the benefits of this diet for heart health is mixed.
- Kidney Problems: Experts widely consider high protein diets to be safe for people with normal kidney function, though those with kidney disease may need to avoid this eating pattern.
- Nutrient Deficiencies: Because carbohydrates include many food groups (like fruits and vegetables), you face a higher risk of missing out on certain nutrients when you cut carbs.
- Constipation: A low-carb, high-protein diet can lower your fiber intake and lead to constipation.
Ketogenic (Keto) Diet
- Nutrient Deficiencies: The keto diet is very low in carbs, which means you can't eat many fruits and vegetables. Most people following a strict keto diet should take a multivitamin with minerals to ensure they're meeting those vitamin and mineral needs.
- Possible Negative Effects on Heart Health: There are mixed results in studies that examine the specific effects of the keto diet on heart health. This is likely because much of it depends on individual food choices.
- Constipation and other gastrointestinal (GI) troubles: Constipation is likely the greatest long-term complication of the keto diet because of a low fiber intake.
- Bone Health Issues: There can be issues with bone health when people switch to low-carb keto diets. Researchers see that markers for bone breakdown are higher and markers for bone building are lower.
- Keto Flu: 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.
- Kidney Problems: The kidneys help metabolize protein, and McManus says the keto diet may overload them.
- Fuzzy Thinking and Mood Swings: The brain works best when the energy source is sugar from healthy carbohydrates to function.
Who Should Avoid These Diets?
Certain groups should avoid high-protein, low-carb diets due to related health risks. It is suggested to avoid a high-protein, low-carb diet if you have certain conditions and health issues, such as:
- Kidney disease or kidney issues, as too much protein strains your kidneys
- History of disordered eating or eating disorders, as low-carb diets promote restrictive eating
- Pregnancy or breastfeeding, as nutrient-dense diets are critical during these stages
Practical Considerations
Sustainability
Both high-protein and keto diets can be challenging to maintain long-term due to their restrictive nature. The keto diet, in particular, requires strict adherence to macronutrient ratios, which can be difficult for many people.
Working with a Professional
While many "self-direct" themselves through a keto diet, the ideal protein diet has the added accountability that comes from working with a professional.
Budget
Some of the cheaper high protein, low carb foods available include eggs, canned foods like fish, beans, and lentils, cottage cheese, Greek yogurt, tofu, and ground meats like chicken, beef, and pork. Consider opting for “own brand” products instead of brand names, as these are usually more affordable.
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