A low-carb diet is a way of eating where you cut back a lot on carbohydrates, found in foods such as bread, rice, pasta, potatoes, and fruit. Instead, you eat more foods with protein and fat. Most people try a low-carb diet to lose weight, but it may also help with blood sugar control and lower the risk of health problems like type 2 diabetes and metabolic syndrome. Low-carb eating plans have existed for a long time, and there are many types, each allowing for different amounts of carbohydrates.
What Is a Low Carb Diet?
Definition and Breakdown
Simply put, a low-carb diet means eating fewer carbohydrates than most people usually do. There isn’t a set definition, but all low-carb plans involve cutting down on carb-rich foods. This often means avoiding or eating much less sugar, bread, pasta, and other foods high in carbs. Instead, you eat more meats, poultry, fish, eggs, cheese, nuts, seeds, and vegetables that are low in carbs, such as leafy greens and other non-starchy vegetables.
Because there’s no single rule for how low in carbs a diet must go to be called “low-carb,” studies and health groups use different numbers. For example, some say low-carb is less than 20% of daily calories from carbohydrates, while others use 25% as the cutoff. This means there are several types of low-carb diets, each with their own rules and limits.
How Many Carbohydrates Are Low?
The amount of carbohydrates considered “low” can change based on the specific diet or your personal goals, but some rough guidelines are available. Usually, a daily low-carb diet means eating about 20 to 57 grams of carbohydrates per day-that’s around 0.7 to 2 ounces, or about 80 to 240 calories from carbs. For comparison, regular recommendations for a 2,000-calorie diet suggest that about 900 to 1,300 of those calories should come from carbohydrates (45% to 65% of total calories).
To make it clearer, see the table below:
| Diet Type | % Calories from Carbs | Grams of Carbs per Day |
|---|---|---|
| Very Low-Carb (Keto) | Less than 10% | 20-50g |
| Standard Low-Carb | Less than 26% | Less than 130g |
| General Recommendation | 45%-65% | 225-325g |
For reference, a slice of bread or a regular-sized apple contains about 15-20 grams of carbs, while a large baked potato or a liter of orange juice can have around 90 grams.
Macronutrient Balance in Low Carb Diets
When carbs are lowered, you eat more protein and fat to make up for fewer calories from carbs. The three main nutrients your body uses for energy are carbohydrates, fat, and protein. In most low-carb diets, there isn’t a strict rule for how much protein or fat to eat-just eat until you are satisfied. Some versions, like keto, focus more on fat (around 60-80% of calories), while others may let you eat more protein. The idea is to switch your body’s main energy source from sugar to fat and protein.
What Are the Types of Low Carb Diets?
Low-carb diets come in many forms, ranging from a gentle reduction in carbs to plans that almost cut them out completely. Here are the main types:
- Standard Low-Carb Diet: This is a flexible plan that keeps carbs under 26% of your daily calories (130 grams or less per day). You can still have some fruits, vegetables, and small amounts of whole grains. The main focus is on eating more proteins, healthy fats, and non-starchy vegetables, while keeping away from sugar and highly processed carbs.
- Ketogenic Diet (Keto): Keto is the strictest form of low-carb eating. Carb intake is usually limited to 20-50 grams per day (less than 10% of calories), forcing the body to go into a state called ketosis. In ketosis, your body turns fat into energy instead of carbs. The diet is mostly fat (60-80% of calories), with moderate protein. Originally, keto was used to help epilepsy, but now it’s also popular for quick weight loss.
- Very Low-Carb Diet: This is basically similar to the keto diet, keeping carbs extremely low to make sure the body stays in ketosis for steady fat burning.
- Moderate Low-Carb Diet: These diets allow a bit more flexibility with 26% to 44% of calories from carbs. This is a good option if you don’t want to follow very strict limits. It’s still lower in carbs than most diets and can still help with weight and blood sugar management.
Choosing the best type depends on your health, weight goals, and personal preference. It’s a good idea to talk with your doctor before making big changes to your diet.
How Does a Low Carb Diet Work?
The main idea behind a low-carb diet is to change the way your body gets its energy. By lowering carbs, your body starts to use stored fat for fuel instead of sugar, which can help with weight loss and possibly improve other health conditions.
How the Body Uses Carbohydrates
Normally, your body breaks down carbs from food into sugar (glucose). This sugar enters the blood, raising your blood sugar levels. The pancreas then makes insulin, a hormone that helps move sugar into your cells for energy. Extra sugar that isn’t used right away is stored in your liver and muscles as glycogen or turned into fat for long-term storage.
If you eat a lot of carbs, your insulin stays high, and you tend to store more fat. Eating fewer carbs can lower insulin levels and help your body use stored fat for energy.
Idea Behind Low-Carb Diets and Insulin
Supporters of low-carb diets say that eating lots of carbs keeps insulin high, which tells your body to store fat instead of burning it. By cutting carbs, insulin drops, so your body can start using fat for energy. This is called the “carbohydrate-insulin hypothesis.” Some research disagrees about whether low-carb diets boost your metabolism more, but it is clear that less insulin can help reduce fat storage. Also, more protein and fat help you feel fuller, leading to less food overall.
Which Foods Are Included and Avoided on a Low Carb Diet?
Switching to a low-carb diet is about choosing the right foods. The key is to avoid or limit high-carb foods and focus on those higher in protein, healthy fats, and low in carbs.
Foods to Eat on a Low Carb Diet
- Meat (beef, pork, lamb, poultry, etc.)
- Fish and seafood
- Eggs
- Healthy fats (olive oil, avocado, butter, coconut oil, etc.)
- Nuts and seeds
- Full-fat dairy (cheese, cream, yogurt – as allowed)
- Low-carb vegetables (spinach, kale, lettuce, broccoli, cauliflower, peppers, asparagus, cucumbers, Brussels sprouts)
- Small amounts of berries
Foods to Avoid or Limit
- Sugary foods (soda, candy, cakes, cookies, desserts)
- Grains (bread, pasta, rice, cereal, oats, corn)
- Starchy vegetables (potatoes, sweet potatoes, peas, corn)
- Beans and lentils (some plans allow small amounts)
- Most fruits (bananas, mangoes, pears)
- Snack foods (chips, crackers, pretzels)
What Are the Benefits of a Low Carb Diet?
A low-carb diet can have many benefits, especially for weight control and some health issues.
Weight Loss
Low-carb diets are well known for helping with weight loss. By lowering carbs, your body burns more fat for energy. Many people lose weight more quickly at first because your body loses water as glycogen stores are used up. Focusing on more protein and fat can also help you feel full longer, making it easier to eat less without feeling hungry. Long-term, sticking with any healthy plan is most important for keeping weight off.
Blood Sugar and Diabetes
For people with type 2 diabetes or those with high blood sugar, eating fewer carbs can make a big difference. Since carbs raise blood sugar and insulin, cutting them can help lower both, making it easier to control diabetes. Some people with diabetes may even need less medication, which should be managed with a doctor’s help. Reducing carbs can also help prevent type 2 diabetes by improving how your body uses insulin.
Heart Health
Low-carb diets, especially those with healthy fats and lean proteins, may also help improve heart health. They can lower triglycerides and boost HDL (“good”) cholesterol. Both are important for reducing the risk of heart problems. Weight loss and better blood sugar levels are also good for your heart. Choose healthy fats (like olive oil and avocados) and limit saturated and processed fats for best results.
What Are the Risks and Things to Watch for with Low Carb Diets?
While low-carb diets have benefits, there are some possible downsides. Always check with your doctor before making major changes, especially if you have health problems.
Short-Term Side Effects
When you first start a low-carb diet, you may notice things like headache, tiredness, constipation, or muscle cramps. Some call this the “keto flu.” You might also have bad breath for a while. These effects usually go away after a few days or weeks as your body gets used to the new way of eating. Drinking enough fluids and making sure you get enough salt, potassium, and magnesium can help. If symptoms are strong or stick around, talk to a doctor.
Possible Long-Term Risks
It is less clear what happens to your health if you stay on a low-carb diet for years. Some people may not get enough fiber, vitamins, or minerals if they cut out too many fruits, vegetables, and grains. Not eating enough fiber can cause digestive problems. Eating too much saturated fat or too many processed meats can also be risky for your heart over time. Some large studies suggest that eating a lot of animal fats and proteins on a very low-carb diet can raise the risk of heart disease or cancer. Choosing more plant-based proteins and healthy fats can make a low-carb diet safer and healthier.
If you already have heart disease or blocked arteries, very strict low-carb diets may not be recommended. It’s smart to have your doctor check your health regularly if you choose this approach for a long time.