Should You Use a Low-Carb Diet for Weight Loss?

atkins diet carbohydrates carnivore diet elimination diet fats glucose ketogenic diet ketosis low-carb diet paleo diet processed foods protein weight loss whole foods Jan 25, 2025

A colorful display of healthy foods, featuring fresh fruits, vegetables, and grains, emphasizing nutritious low-carb choices.

Are you among the millions of Americans who planned to start a diet in 2025? Almost half of all U.S. adults did, according to a survey by the Physicians Committee for Responsible Medicine. Among the respondents, 26 percent preferred low-carb diets like Atkins and keto.¹

Cutting down on carbs is a popular strategy for weight loss. But with so many low-carb regimens out there, which one should you follow? In this article, we’ll take a look at the science behind low-carb diets, as well as explore four popular low-carb diets, outlining their potential benefits and drawbacks to help you decide.

Low-carb diets 101
Carb vs. fat metabolism
Carnivore diet
Atkins diet
Keto diet
Paleo diet

Let’s begin at the beginning. What is a low-carb diet, exactly?

Low-carb diets 101

A low carb diet is simply one where you reduce your carbohydrate intake. Typically, the focus is on limiting simple carbs, which are common in grains, breads, sweets, pastas, fruits, and some vegetables. Some diet plans also have you avoid nuts and seeds.²

For reference, the Dietary Guidelines for Americans recommend that 45 percent to 65 percent of your total daily calories come from carbs. But given that obesity rates have nearly tripled since the government began offering diet advice, it’s no surprise that people are now skeptical of the official recommendations. This has led to an increased interest in diets that take the opposite approach.^2,3

If you follow the official recommendation and consume 2,000 calories a day, carbs would account for between 900 and 1,300 of those calories. Low-carb diets reduce carb intake below 200 grams per day, and sometimes much lower.²

There are many types of low-carb diets. While they all aim to make you lose weight, they vary in their food choices, macronutrient ratios, and overall philosophies. They each pose different health risks too. But why would reducing carbs make you lose weight? The answer has to do with how your body fuels itself.

Carb vs. fat metabolism

Carbs are your body’s preferred source of energy. During digestion, carbs quickly break down into glucose. This simple sugar is carried throughout your body in your blood to all the places where it’s needed to fuel your cells. Blood glucose that isn’t used immediately gets stored in your liver and muscles, or turned into body fat.²

Very low carb intake depletes your glucose stores. As a result, your body starts burning fat for energy in a process called ketosis. The breakdown of fat in your liver produces compounds called ketones, which become the main energy source for your body and brain whenever glucose isn’t directly available.⁴

What about protein? Protein is metabolized to amino acids, which are first used to repair your body’s tissues. But after that, excess amino acids are mostly converted to glucose.⁵

Glycolysis (sugar burning) happens fast and uses up the available fuel quickly. As a result, you need to refuel more often. Because ketosis proceeds more slowly and more energy is available from each gram of fat, you don’t need to eat as much or as often. Together, these benefits promote weight loss.⁶

Let’s now take a look at four of the most popular low-carb diets: carnivore, Atkins, keto, and paleo.

Carnivore diet

The carnivore diet is the most restrictive of the diets we’ll cover here. It basically allows only meat and fish, and a few other animal-based products.^7,8

On a carnivore diet, you don’t eat any vegetables, fruits, grains, legumes, nuts, or seeds. For this reason, the carnivore diet is sometimes called the “zero carb” diet.⁸

Because the carnivore diet completely eliminates such a wide range of foods, it can be difficult to follow. It’s also important to focus on high-quality animal products, as CAFO or processed meat products can lead to sodium imbalance and unhealthy lipid profiles. You may also miss out on beneficial plant-based nutrients and antioxidants. Some people experience constipation, perhaps due to low fiber intake. This same lack of fiber may eventually contribute to other long-term health problems, including colon cancer.⁷

Atkins diet

The Atkins diet is named for Dr. Robert Atkins, who wrote a book about it that was popular in the 1990s. His goal was to offer a plan for sustainable weight loss. The diet consists of four phases: induction, balancing, fine-tuning, and maintenance.^9,10

In the induction phase, you kick-start your weight loss by consuming just 20 to 25 grams of carbs a day for two weeks. You eat foods rich in fat and protein, along with leafy greens and other low-carb veggies. Then, in the balancing phase, your daily carb allotment rises to between 25 and 50 grams. You slowly reintroduce berries, melon, cottage cheese, yogurt, and other full-fat dairy. When you’re about 10 lb away from your target weight, you enter the fine-tuning phase. At this point, you eat between 50 and 80 grams of carbs per day until your weight loss slows down. Finally, in the (lifetime) maintenance phase, you’re allowed to eat up to 100 g of healthy carbs, as long as you don’t gain weight back.^9,11,12

The Atkins diet requires you to avoid or limit sugar (found in sodas, juices, cakes, candy, and similar processed foods); “low fat” and “diet” foods (which tend to have a lot of sugar); and refined grains (white bread, white pasta, and white rice). In the induction phase, you’ll also have to abstain from high-carb fruits (bananas, apples, grapes, etc.); starchy veggies (potatoes and sweet potatoes); and legumes (beans, lentils, chickpeas, etc.)⁹

On the other hand, doing the Atkins diet means eating meats, fatty fish and seafood, and omega-3 enriched or pastured eggs. You should consume full-fat dairy and other healthy fats too. Atkins allows you to eat low-carb veggies, nuts and seeds, and eventually some whole grains as well.⁹

Most people who try Atkins wind up eating a lot of protein and not very much fat. As a result, side effects can include headaches, dizziness, weakness, fatigue, and constipation, especially in the early phases of the diet. Low blood sugar, kidney issues, and electrolyte imbalance are also possible.⁹

Keto diet

The keto diet (short for “ketogenesis”) is very low in carbs and moderate in protein. Unlike Atkins, keto requires maintaining a drastic reduction of your carb intake. You’ll replace those calories with calories from fat — ideally 70 to 80 percent of your daily calories. This puts your body in a state of ketosis and keeps it there.¹³

The standard keto diet restricts your carbs to 20 grams per day, regardless of your total daily calories. It also restricts protein to 0.6 to 1 gram per pound of lean body mass. The total calories from both protein and carbs typically adds up to around 25 percent of your total daily calories.^14,15,16

To achieve this, you’ll have to avoid sugary foods, grains or starches, legumes, root vegetables, and low-fat and sugar-free diet products, as well as most sauces and alcoholic beverages.¹³

As for what to eat, a keto diet is based around meat, fatty fish, eggs, butter, cream, and unprocessed cheese. You’re also allowed certain nuts and seeds, healthy oils, avocadoes, and low-carb, high-fiber veggies. Condiments like salt, pepper, herbs, and spices are OK too. Overall, it’s best to focus on whole, single-ingredient foods.¹³

It can be challenging to get used to the idea of eating so much fat. It often happens that people simply douse everything in salad oil, trying to achieve the requisite fat consumption. But neglecting to eliminate unhealthy fats, especially vegetable oils, can lead to inflammation and even heart disease.¹⁷

Rarely, the keto diet may put you at risk of low blood protein levels, high liver fat, kidney stones, and micronutrient deficiencies. And if you have type-2 diabetes and are taking sodium-glucose cotransporter 2 (SGLT2) inhibitor medication, it’s best not to do keto. That’s because SGLT2 inhibitor drugs make you more prone to diabetic ketoacidosis — a life-threatening condition where your blood becomes too acidic.¹³

Paleo diet

The paleolithic “paleo” diet is the least restrictive of the diets on our list. It doesn’t focus on macronutrient ratios. Instead, the idea is to try to approximate the way our hunter-gatherer ancestors ate millennia ago.^18,19

In reality, paleolithic humans’ diets varied based on where they lived and what was available to them at the time. Some of them ate a lot of game meat, while others ate fish, and still others thrived on lots of plants.¹⁹

But one thing’s for sure: Our ancestors didn’t eat any of the processed foods that are so ubiquitous in the modern world. Thus, the paleo diet discourages foods and drinks with added sugar and/or salt; refined grain products like bread and pasta; legumes; most dairy; vegetable oils; artificial sweeteners; and “diet” or “low fat” foods (which tend to have many additives).¹⁹

The paleo diet advocates eating whole, unprocessed, and nutrient-dense foods. These include meats (grass-fed if possible), fish and seafood (ideally wild-caught), free-range or pastured eggs, vegetables, fruits, and healthy fats and oils.^18,19

The inclusion of a wide variety of whole, natural foods means many people find it easier to stick to paleo, and the side effects are relatively few. One common pitfall is that the paleo diet allows fruit and “natural” sugars such as maple syrup. Unfortunately, these items are available in much greater quantities now than our ancestors ever encountered. Without a macronutrient limitation to look to, it can be easy to overconsume these yummies on paleo. As a result, weight loss may stall or even be reversed.²⁰

Conclusion

So, is reducing carb intake the right choice for YOU? While all the low-carb diets we’ve discussed can be effective for shedding pounds, each also comes with distinct benefits and drawbacks.

Ultimately, your body is unique, and what works for someone else might not work for you. So, before you overhaul your diet, consider talking to a diet expert — someone who can help you figure out if going low-carb aligns with your personal goals and health conditions.

Finding a balanced approach that fits YOUR needs is the key to long-term success. Ready to take control of your health and discover the best diet for YOU? Go here to Maximize Your Performance and receive a personalized consultation to optimize your wellness journey!

References

Should You Use a Low-Carb Diet for Weight Loss?

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