Can a low-carb diet help you lose weight? (2024)

Low-carb diet: Can it help you lose weight?

Could a low-carb diet give you an edge in losing weight?

By Mayo Clinic Staff

Definition

A low-carb diet limits carbohydrates, often called carbs — such as those found in grains, starchy vegetables and fruit. A low-carb diet focuses on foods high in protein and fat. Many types of low-carb diets exist. Each diet has varying limits on the type and amount of carbs you can eat.

Purpose

A low-carb diet is generally used for weight loss. Some low-carb diets may have health benefits beyond weight loss, such as lowering your risk of type 2 diabetes and metabolic syndrome.

Why you might follow a low-carb diet

You might choose to follow a low-carb diet because you:

  • Want a diet that limits some carbs to help you lose weight.
  • Want to change your overall eating habits.
  • Enjoy the type and amount of food used in low-carb diets.

Check with your health care provider before starting any weight-loss diet, especially if you have any health conditions, such as diabetes or heart disease.

Diet details

A low-carb diet limits the amount of carbohydrates you eat. Carbs are grouped as:

  • Simple natural, such as lactose in milk and fructose in fruit.
  • Simple refined, such as table sugar.
  • Complex natural, such as whole grains or beans.
  • Complex refined, such as white flour.

Common sources of natural carbohydrates include:

  • Grains.
  • Fruits.
  • Vegetables.
  • Milk.
  • Nuts.
  • Seeds.
  • Legumes, such as beans, lentils and peas.

In general, you digest complex carbs more slowly. Complex carbs also have less effect on blood sugar than refined carbs do. They also offer fiber.

Refined carbs such as sugar or white flour are often added to processed foods. Examples of foods with refined carbs are white breads and pasta, cookies, cake, candy, and sugar-sweetened sodas and drinks.

The body uses carbs as its main energy source. During digestion, complex carbs are broken down into simple sugars, also called glucose, and released into your blood. This is called blood glucose.

Insulin is released to help glucose enter the body's cells, where it can be used for energy. Extra glucose is stored in the liver and in muscles. Some is changed to body fat.

A low-carb diet is meant to cause the body to burn stored fat for energy, which leads to weight loss.

Typical foods for a low-carb diet

In broad terms, a low-carb diet focuses on proteins and some nonstarchy vegetables. A low-carb diet generally limits grains, legumes, fruits, breads, sweets, pastas and starchy vegetables, and sometimes nuts and seeds. But some low-carb diet plans allow small amounts of fruits, vegetables and whole grains.

A daily limit of 0.7 to 2 ounces (20 to 57 grams) of carbohydrates is typical with a low-carb diet. These amounts of carbohydrates provide 80 to 240 calories. Some low-carb diets greatly limit carbs during the early phase of the diet. Then those diets allow more carbs over time.

In contrast, the Dietary Guidelines for Americans recommend that carbohydrates make up 45% to 65% of your total daily calorie intake. So if you eat or drink 2,000 calories a day, carbs would account for between 900 and 1,300 calories a day.

Results

Weight loss

Most people can lose weight if they limit calories and boost their physical activity. To lose 1 to 1.5 pounds (0.5 to 0.7 kilograms) a week, you need to eat 500 to 750 fewer calories each day.

Low-carb diets, especially very low-carb diets, may lead to greater short-term weight loss than do low-fat diets. But most studies have found that at 12 or 24 months, the benefits of a low-carb diet aren't very large.

Cutting calories and carbs may not be the only reason for the weight loss with low-carb diets. Some studies show that you may shed some weight because the extra protein and fat helps you feel full longer. Feeling full longer helps you eat less.

Other benefits

Low-carb diets that focus on healthy sources of carbs, fat and protein may help lower the risk of type 2 diabetes and heart disease. In fact, almost any diet that helps you shed excess weight may improve blood sugar and cholesterol levels, at least in the short term.

Risks

A sudden and large drop in carbs can cause short term side effects, such as:

  • Constipation.
  • Headache.
  • Muscle cramps.

Severe carb limits can cause your body to break down fat into ketones for energy. This is called ketosis. Ketosis can cause side effects such as bad breath, headache, fatigue and weakness.

It's not clear what kind of possible long-term health risks a low-carb diet may pose. If you limit carbs in the long term, it may cause you to have too little of some vitamins or minerals and to have digestive issues.

Some health experts think that if you eat large amounts of fat and protein from animal sources, your risk of heart disease or certain cancers may go up.

If you opt to follow a low-carb diet, think about the fats and proteins you choose. Limit foods with saturated and trans fats, such as meat and high-fat dairy products. These foods may make your risk for heart disease go up.

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Nov. 15, 2022

  1. Ebbeling CB, et al. Effects of a low carbohydrate diet on energy expenditure during weight loss maintenance: Randomized trial. BMJ. 2018; doi:10.1136/bmj.k4583.
  2. Raynor HA, et al. Position of the Academy of Nutrition and Dietetics: Interventions for the treatment of overweight and obesity in adults. Journal of the Academy of Nutrition and Dietetics. 2016;116:129.
  3. Duyff RL. Carbs: Sugars, starches, and fiber. In: Academy of Nutrition and Dietetics Complete Food and Nutrition Guide. 5th ed. Houghton Mifflin Harcourt; 2017.
  4. Westman EC, et al. Using a low-carbohydrate diet to treat obesity and type 2 diabetes mellitus. Current Opinions in Endocrinology, Diabetes and Obesity. 2020; doi:10.1097/MED.0000000000000565.
  5. Gepner Y, et al. The beneficial effects of Mediterranean diet over low-fat diet may be mediated by decreasing hepatic fat content. Journal of Hepatology. 2019; doi:10.1016/j.hep.2019.04.013.
  6. 2015-2020 Dietary Guidelines for Americans. U.S. Department of Health and Human Services and U.S. Department of Agriculture. https://health.gov/dietaryguidelines/2015/guidelines. Accessed Oct. 22, 2020.
  7. Kirkpatrick C, et al. Review of current evidence and clinical recommendations on the effects of low-carbohydrate and very-low-carbohydrate (including ketogenic) diets for the management of body weight and other cardiometabolic risk factors: A scientific statement from the National Lipid Association Nutrition and Lifestyle Task Force. Journal of Clinical Lipidology. 2019; doi:10.1016/j.jacl.2019.08.003.
  8. Perreault L. Obesity in adults: Dietary therapy. https://www.uptodate.com/contents/search. Accessed Oct. 22, 2020.
  9. Freire R. Scientific evidence of diets for weight loss: Different macronutrient composition, intermittent fasting, and popular diets. Nutrition. 2020; doi:10.1016/j.nut.2019.07.001.
  10. Shan Z, et al. Association of low-carbohydrate and low-fat diets with mortality among US adults. JAMA Internal Medicine.2020; doi:10.1001/jamainternmed.2019.6980.
  11. Evert AB, et al. Nutrition therapy for adults with diabetes or prediabetes: A consensus report. Diabetes Care. 2019; doi:10.2337/dci19-0014.
  12. Gordon B. What is the ketogenic diet? Academy of Nutrition and Dietetics. https://www.eatright.org/health/weight-loss/fad-diets/what-is-the-ketogenic-diet. Accessed Nov. 11, 2020.

See more In-depth

Products and Services

  1. The Mayo Clinic Diet Online
  2. A Book: The Mayo Clinic Diet Bundle

See also

  1. Artificial sweeteners and other sugar substitutes
  2. Atkins Diet
  3. Coffee calories
  4. HCG diet
  5. High-protein diets
  6. South Beach Diet
  7. Weight-loss options
  8. Energy density

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Can a low-carb diet help you lose weight? (2024)

FAQs

Can a low-carb diet help you lose weight? ›

Weight loss

Is a low-carb diet really good for you? ›

Low-carb diets can be good for heart health, since they may increase good cholesterol levels, and decrease blood pressure and triglyceride levels. Studies show that some people successfully lose weight on a low carb diet, just as they can on a lower fat or Mediterranean-style diet.

How long does it take to see results from a low-carb diet? ›

Within one to two weeks of starting the diet, users usually see the biggest weight loss. Why does this happen? First, when insulin drops, the kidneys remove extra sodium from the body. Second, when someone restricts their carb intake, glycogen — the stuff that keeps extra water in the organs — also goes down.

How much weight can you lose in a week on a low-carb diet? ›

If a person follows the 75% fat /20% carb/5% fat keto diet, average results may look like this: Weeks 1–2: rapid weight reduction phase due to water loss – up to ten pounds. Weeks 2–4: standard weight reduction – between one and two pounds per week. After the first month – slow weight loss – around one pound per week.

Why not losing weight on a low-carb diet? ›

You have been cutting carbs for too long. If you eat at a calorie deficit for many months or years, your metabolic rate may start to slow down. If you have been dieting for a long time, try taking a 2-month period where you aim to maintain your current weight and gain some muscle.

What happens if I eat no carbs for a month? ›

Severe carb limits can cause your body to break down fat into ketones for energy. This is called ketosis. Ketosis can cause side effects such as bad breath, headache, fatigue and weakness.

What are the dangers of a no carb diet? ›

Complications such as heart arrhythmias, cardiac contractile function impairment, sudden death, osteoporosis, kidney damage, increased cancer risk, impairment of physical activity and lipid abnormalities can all be linked to long-term restriction of carbohydrates in the diet.

How long does it take to lose 20 pounds on a low-carb diet? ›

“If the patient can maintain a steady calorie deficit, I expect them to lose one to two pounds per week,” says Dr. Seeman. So after 12 weeks, her clients are usually down around 20-25 pounds.

Will a low-carb diet reduce belly fat? ›

Reducing your carb intake can be very beneficial for losing fat, including abdominal fat. In fact, low carb diets may cause belly fat loss in people with overweight, those at risk for type 2 diabetes, and people with polycystic ovary syndrome (PCOS) ( 31 , 32 , 33 ).

How long does it take to lose 15 pounds on a low-carb diet? ›

It's been found that most weight loss occurs in the early stages of a ketogenic diet and that those who are on the ketogenic diet for a more extended period of time (12 weeks to 12 months), don't experience major weight loss changes. On average, people: Lost 15 lbs in body weight after 4 weeks, and.

What is the fastest way to lose weight on a low-carb diet? ›

To achieve effective weight loss on a low-carb diet, you'll need to:
  1. Keep carbohydrate intake low.
  2. Protein intake moderate.
  3. Fat intake high.
  4. Avoid snacking.
  5. Exercise regularly.

Is 100 carbs a day low-carb? ›

The range of evaluated studies – all published between 2002 and 2022 – found that most trials defined low-carb as having 100 grams or less of carbohydrates daily. But many also had much stricter definitions, with carbs taking up only 40-60 grams per day.

What is the 30 30 30 rule for weight loss? ›

The 30-30-30 rule involves eating 30 grams of protein within 30 minutes of waking up, followed by 30 minutes of low-intensity, steady state cardiovascular exercise. Beyond these steps, the 30-30-30 method doesn't require any changes to other meals or behaviors, restrictions or counting calories.

Why am I getting fatter on a low-carb diet? ›

The Scale Is Starting to Creep Up. There are few things worse than going on a diet and seeing your weight actually increase. Unfortunately, this can be the case for low-carb dieters because your body is reacting to this decreased carbohydrate intake by trying to produce its own usable glucose from protein or fat.

How many carbs should I eat a day to lose weight? ›

As far as how many carbohydrates to eat, Pratt says 100 to 150 grams of carbohydrates is safe for most people who are trying to lose weight. It may be better for some people to eat carbs consistently throughout the day. “You can also break it up evenly with 40 to 50 grams of carbs per meal,” she says.

What happens if I eat too many carbs on a low-carb diet? ›

Eating more than 50 grams of carbs may disrupt ketosis.

Some people can eat more and still stay in ketosis, whereas others may need to restrict their carb intake more in order to stay in ketosis.

What happens when you cut out carbs? ›

If your body doesn't get enough carbohydrates, you may experience the following side effects: You may feel sluggish. Many people find they feel tired and don't have much energy when they don't eat enough carbs. That's because carbs are the body's main energy source.

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