In the realm of weight-loss diets, low-carbohydrate, high-protein eating plans often capture attention, with the keto and Atkins diets standing out as prominent contenders. Both diets involve restricting carb intake, even in the final phase of the Atkins diet, but their approaches, restrictions, and long-term viability differ significantly. While both aim to promote weight loss and improve health by limiting carb intake, understanding their nuances can help individuals make informed decisions about which, if either, aligns with their goals and lifestyles.
Introduction to Low-Carb Diets
The Paleo, South Beach, and Atkins diets all fit into the low-carbohydrate, high-protein category and are sometimes referred to as ketogenic or "keto" diets. However, a true ketogenic diet is distinct. Unlike other low-carb diets that focus on protein, a keto plan centers on fat, which supplies as much as 90% of daily calories. The keto diet aims to force your body into using a different type of fuel by significantly reducing carb levels so that the body can no longer use them for fuel. In this state, called ketosis, the body starts to burn fat and produce ketones, molecules that serve as a new energy source.
The Keto Diet: A High-Fat Approach
The ketogenic (keto) diet is a very low-carb, moderate-protein, high-fat diet plan. It was first used to treat children who experienced seizures, but researchers discovered that it may benefit other people as well. The keto diet is used to help reduce the frequency of epileptic seizures in children.
Macronutrient Ratios on Keto
On the keto diet, a person's total daily macronutrient intake typically comprises:
- 70-80% fat
- 20-25% protein
- 5-10% carbohydrates
Because the keto diet has such a high fat requirement, followers must eat fat at each meal. In a daily 2,000-calorie diet, that might look like 165 grams of fat, 40 grams of carbs, and 75 grams of protein.
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Food Choices on Keto
Some healthy unsaturated fats are allowed on the keto diet - like nuts (almonds, walnuts), seeds, avocados, tofu, and olive oil. All fruits are rich in carbs, but you can have certain fruits (usually berries) in small portions. Vegetables (also rich in carbs) are restricted to leafy greens (such as kale, Swiss chard, spinach), cauliflower, broccoli, Brussels sprouts, asparagus, bell peppers, onions, garlic, mushrooms, cucumber, celery, and summer squashes. Keto diet proponents recommend getting the carbs allowed from specific foods, including keto-friendly vegetables, such as leafy greens, and certain fruits, primarily berries. The diet excludes grains and legumes.
Potential Benefits of Keto
- Weight loss: A keto diet may bring about an initial, dramatic weight loss, which can be traced to the breakdown of glucose in the body. Research indicates that being in ketosis decreases appetite, thereby removing one of the biggest barriers to weight loss - constant hunger. Ketogenic diets may also preserve your muscle mass, meaning that most of the weight loss you may experience is more likely to be a result of fat loss.
- Lower blood sugar levels: When you lower your carb intake, your blood sugar levels decrease and your insulin sensitivity increases, which could be beneficial for someone with diabetes or pre-diabetes.
- Focus on natural foods: The keto diet encourages a person to eat unprocessed foods.
- Other Benefits: There is emerging evidence these diets may help with other issues, such as acne and neurological disorders, although confirming this will require more research.
Risks and Side Effects of Keto
A ketogenic diet has numerous risks.
- High in saturated fat: Top of the list: it's high in saturated fat. McManus recommends that you keep saturated fats to no more than 7% of your daily calories because of the link to heart disease.
- 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.
- Nutrient Deficiency: Because you’re seriously limiting certain macros, following a low-carb diet could become deficient in certain nutrients, including vitamin A, B vitamins, vitamin E, calcium, folate, iron, magnesium, and potassium, according to a 2021 study published in Frontiers in Nutrition.
- Dehydration: Carbs help our body retain excess water and electrolytes, including sodium. On keto, when you cut out the majority of carbs, your body loses a lot of sodium and fluids all at once, which could lead to dehydration.
- Keto flu: Any diet that involves ketosis can cause adverse effects, such as keto breath, keto skin rashes, and keto flu.
- Muscle loss: Ketosis may help burn fat, but it may also burn muscle to use for energy. Following a very low carb diet can result in a loss of muscle mass.
The Atkins Diet: A Phased Approach to Carb Restriction
Dr. Robert Atkins developed the Atkins diet as a simple, low carbohydrate approach to nutrition. The diet has changed over the years to take on its four stage structure. Like the keto diet, the Atkins diet allows for few carbs, moderate amounts of protein, and high amounts of fat. The Atkins diet is one of the best-known diets worldwide. It’s a low carb, moderate protein, high fat diet.
The Four Phases of Atkins
The Atkins diet follows a four-phase structure, gradually increasing carb intake:
- Phase 1 (Induction): This phase allows for 20-25 grams (g) of net carbs per day until you are 15 pounds (lb), or 7 kilograms (kg), from your goal weight. People stay in this phase until they are 15 pounds from their ideal weight.
- Phase 2 (Balancing): During this phase, people eat 25-50 g of carbs each day. During this phase, you consume 25-50 g of net carbs per day until you are 10 lb (5 kg) from your goal weight.
- Phase 3 (Fine-tuning): This allows people to eat up to 80 g of carbs per day until they meet their goal weight and maintain it for at least 1 month. Your net carb allowance is raised to 50-80 g per day until you have met your goal weight and maintained it for 1 month.
- Phase 4 (Maintenance): Phase 4 is the maintenance phase, allowing for 80-100 g of carbs per day. During the final phase, you consume 80-100 g of net carbs per day for ongoing weight maintenance. The final phase is the least restrictive. The aim is to help a person be conscious of their carb intake and maintain a healthful weight.
During the first phase, the body enters ketosis, as in the keto diet. As the person moves through the different phases, they begin to eat more carbs and more varied foods.
Read also: Keto Calorie Counting: A Detailed Guide
Food Choices on Atkins
Depending on the plan individuals follow, the plan emphasizes consuming protein at least three times per day in four to six ounce portions including meat, seafood, poultry and eggs. Fats are encouraged, you want at least 3 tablespoons per day in the form of butter, mayonnaise, or olive or other vegetable oils. It’s also recommended you consume non-starchy veggies, nuts, cheese (although no more than 3 to 4 ounces per day), and unsweetened beverages. While on Atkins, you should avoid eating fruits (though you can slowly reintroduce them), whole grains, legumes, starchy veggies, processed foods, sugar, and refined grains like bread and pasta.
Potential Benefits of Atkins
- Weight loss: For similar reasons to keto, the Atkins diet can result in weight loss, though potentially at a slower rate.
- Lower blood sugar levels: Also similar to keto, Atkins could potentially help lower your blood sugar levels because it’s a low carb diet.
- More protein: Atkins is designed to help you lose weight by following a low-carb diet that prioritizes eating more protein than keto.
- More fiber: On Atkins, you’ll be able to eat fruits, veggies, and whole grains, so your fiber intake might be higher than it would be with keto.
Risks and Side Effects of Atkins
- Not sustainable long-term: The beginning stage of Atkins is incredibly restrictive and requires regimented carb-cutting that could be difficult to keep up.
- Nutritional deficiencies: On Atkins, you could experience a deficiency in B vitamins, certain antioxidants, calcium, potassium, and fiber (at least during the initial stages).
- Dehydration: During the beginning phase of Atkins, when you’ve majorly cut down your carb intake and are losing a significant amount of water weight, you could become dehydrated.
- Keto flu: During the initial low-carb phase of Atkins, as your body adapts to the diet and begins to undergo ketosis, Schiff says it’s definitely possible to experience “keto flu.”
Similarities Between Keto and Atkins
Because they are both low carb diets, Atkins and keto are alike in some ways. In fact, Phase 1 (Induction) of the Atkins diet is similar to the keto diet, as it restricts net carbs to 25 g per day. This will likely cause your body to enter ketosis and start burning fat as its main fuel source. Phase 2 of the Atkins diet prescribes a carbohydrate intake of 25-50 g per day, which may also be low enough for many individuals to enter ketosis.
- Carb Restriction: Both diets require a significant reduction in calories from carbohydrates and encourage a person to get their calories from fats.
- Weight Loss: A number of studies have shown that these diets can result in weight loss, as the body burns fat very well when it enters ketosis. Most relevant studies indicate that a low carb diet produces more weight loss than a low fat diet in the short term, but in the longer term, these diets produce similar weight loss results.
- Focus on natural foods: Both diets encourage a person to eat unprocessed foods. Highly processed foods are linked with obesity, cardiovascular disease, and other health conditions.
Key Differences Between Keto and Atkins
While the keto and Atkins diets share the common ground of carb restriction, several key differences set them apart:
- Carb Intake: The keto diet places more emphasis on carb elimination, and it restricts protein sources, as the body may break down proteins into glucose for energy. The vast majority of calories in the keto diet come from fat. The Atkins diet places strong restrictions on carbohydrate intake at first, but it allows for moderate protein intake. As the person moves through the stages, the Atkins diet becomes more relaxed, allowing for more carbs and a greater variety of foods.
- Ketosis: If a person follows it strictly, the keto diet involves continuous ketosis. However, in the Atkins diet, only the first - and sometimes second - stages involve the carb restriction required to maintain ketosis.
- Long term viability: Some people find that the Atkins diet is an achievable long term option. Though it starts restrictive, a person introduces more foods and carbs as they get close to their goal weight. The last stage, or maintenance stage, of the Atkins diet can feel more manageable than keeping up with the perpetually restrictive keto diet.
Potential Health Benefits of Low-Carb Diets
Both the Atkins and keto diets involve carb restriction, and the effects can be similar. Many people follow the keto or Atkins diets for weight loss. These benefits may result from a reduction in highly processed, high carb foods and excess sugar in the diet.
- Weight Loss: Low carb diets may result in more weight loss than other diet plans.
- Blood Sugar Regulation: Low carb diets have been shown to decrease the need for diabetes medications and improve levels of hemoglobin A1c (HgbA1c), a marker of long-term blood sugar regulation.
- Heart Health: Low carb, higher fat diets may improve certain heart disease risk factors. Low carb diets may reduce triglyceride levels and increase HDL (good) cholesterol, thereby decreasing the ratio of triglycerides to HDL cholesterol.
Risks and Considerations
However, it is dangerous to remain in ketosis for extended periods. Also, most people are unable to maintain a very high fat intake or extreme carb restriction for a long time. Any diet that involves ketosis can cause adverse effects, such as keto breath, keto skin rashes, and keto flu. Staying in a state of ketosis for long periods can be harmful. Also, people following either diet can develop nutrient deficiencies due to food restrictions. For many people, carbohydrate sources are also key sources of fiber. When reducing carbohydrates, people should be sure to get enough daily fiber from other sources, such as vegetables. In addition, these diets may increase the risk of deficiencies in electrolytes and many water-soluble nutrients that come from fruits and vegetables. Finally, ketosis may help burn fat, but it may also burn muscle to use for energy. Following a very low carb diet can result in a loss of muscle mass.
Read also: Magnesium Supplements for Keto
Long-Term Viability and Sustainability
No strong, long term studies indicate that restrictive, low carb diets are healthful for extended periods. In fact, the opposite may be true. Research published in The Lancet Public Health in 2018 found an increased risk of mortality among people following low carbohydrate diets rich in animal protein and fat. The researchers also found that people following diets rich in plant sources of fat and protein had a lower risk of mortality. Many of these plant sources, such as nut butters, whole grains, and legumes, also contain carbohydrates. As a result, they are highly restricted in low carb diets.
Making an Informed Decision
Restrictive diets may help with short term weight loss or fitness goals, but they may not be as healthful in the long term as other options. It’s important to consider your weight loss goals, overall health, and dietary preferences when choosing the best eating pattern for yourself. Low carb diets, particularly those focusing on high quality, nutritious foods, can be beneficial. However, be sure to consult a healthcare professional before making any drastic changes to your diet. Consult a healthcare provider before making any major dietary change. This is especially important for people with chronic health conditions, such as heart disease, diabetes, or high blood pressure. When following any diet that eliminates food groups, make sure to avoid deficiencies by meeting daily nutrient needs in other ways. Once a person reaches their target weight goals, it may be a good idea to switch to a less restrictive diet that incorporates a variety of nutrient-rich foods.