Are Carbs Bad for Weight Loss? Good Carbs vs. Bad Carbs

Carbs (shortened from carbohydrates) are often blamed for weight gain, poor blood glucose control, heart disease, and more.¹ 

Many people resort to very low-carbohydrate diets. While they may be effective for short-term weight loss, long-term use beyond six months results in less beneficial health outcomes.¹ 

Additionally, maintaining a low-carbohydrate diet while consuming a nutritionally adequate diet can be challenging and may cause safety concerns when consuming very low carbohydrates.¹

‍Carbohydrates are essential for optimal health and are your body's preferred primary energy source.² The carbohydrate quality, or source, impacts your health more than a set amount of carbohydrates to eat daily.¹ 

Keep reading to learn about carbohydrates and weight loss, the difference between good and bad carbohydrates, and how a lower-carbohydrate diet filled with beneficial sources can aid weight loss. 

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Carbs and Weight Loss 

Cutting carbohydrate intake (5 to 20 percent) can help with short-term weight loss, but this eating pattern is hard to maintain. 

However, a well-balanced, moderately low-carbohydrate diet in the long term allows for a realistic, nutritious eating plan that supports weight loss. 

In a review article from 2022, including over 60 articles, researchers found no difference in weight loss amounts for individuals following a low-carbohydrate or a balanced-carbohydrate diet (45 to 65 percent carbohydrates) for up to two years.³ 

Weight loss can be achieved in various ways customized to your lifestyle and eating preferences. Some people find reducing carbohydrate intake works best, whereas others follow a low-fat diet.⁴ 

The most important factor is finding a sustainable, nutritious eating pattern that puts you in an energy deficit. An energy deficit can be achieved by eating fewer calories or burning more through exercise (or a combination).⁴ 

What are Carbs?

Carbohydrates are one of three macronutrients your body relies on to function. Protein and fat are the other two macronutrients.

Carbs is a term that encompasses all types of foods classified as carbohydrates based on their chemical structure. The different carbohydrate structures (simple or complex) determine how your body digests and absorbs the energy found within.² 

Your digestive system breaks down simple and complex carbohydrates to glucose. Simple carbohydrates are digested quicker than complex carbohydrates, which contain beneficial fiber that helps keep you full, support healthy gut bacteria, and stabilize blood sugar levels.²

Glucose is needed for body functions and physical activity. Glucose is transported via the blood to all the tissues that need energy. The brain, kidney, marrow, reproductive tissues, and red blood cells alone require 170 grams (680 calories) daily to function optimally. This is one-third of a 2,000-calorie diet.⁵ 

Healthful foods that provide carbohydrates include fruits, vegetables, legumes, and whole-grain products.² Some carbohydrate sources like excessive added sugar are associated with an increased risk of type 2 diabetes, prediabetes, heart disease, and obesity.⁷ 

Low Carb Diets

Low-carbohydrate diets for short-term weight loss often limit daily carbohydrate intake to 5 to 20 percent of their calories, or 25 to 100 g (or 100 to 400 calories) daily, resulting in more calories from fat and protein. These diets are called ketogenic diets or keto diets.¹ 

Research shows that these low carbohydrate diets lead to short-term weight loss, but these benefits are outweighed by the inability to practice long-term (past six months) and increased health risks from consuming high fat and protein.¹

A moderate-carbohydrate diet contains 45 to 65 percent carbohydrates, whereas a low-carb diet contains 5 to 20 percent. 

Some people can meet their nutrient, fiber, fruit, vegetable, whole grains, and bean goals with a lower-carb diet. Still, many need closer to 45 percent of their daily carbohydrate intake to accommodate all their nutrition needs.

Some risks of consuming too few carbohydrates and their respective vitamins, fiber, and food groups can lead to constipation, deficiencies, reduced gut health, and altered heart health.¹ Additionally, high fat and protein intake on low-carb diets can worsen cholesterol levels.²

<div class="pro-tip"><strong>Learn More: </strong><a href=do-carbs-make-you-gain-weight>Do Carbs Make You Gain Weight? The Truth Explained</a>.</div>

How Many Carbs Should I Eat to Lose Weight?

Every person has unique carbohydrate needs that vary throughout different life stages. The amount of carbohydrates needed for weight loss also depends on age, sex, physical activity levels, and medical conditions.⁵

The Dietary Guidelines for Americans recommend that healthy adults should generally get 45 to 65 percent of their daily calories from carbohydrates.^{5, 7}

That equates to about 225 to 325 g (or 900 to 1,300 calories) daily, based on a 2,000-calorie diet. These carbohydrates should come from complex carbohydrates, which include beneficial fiber that stabilizes your blood sugar and keeps you full.⁵ 

When 45 to 65 percent of your calories come from carbohydrates, the rest come from 10 to 35 percent protein and 20 to 35 percent fat.⁷ 

If you are eating more than the recommended 45 to 65 percent of daily calories from carbohydrates, try reducing your intake to this range. 

Then, swap simple carbs and refined carbs for fiber-rich (complex) carbohydrates paired with lean protein and healthy fats to balance your meals, stabilize blood sugar levels, and reduce hunger. 

Work with a registered dietitian to determine the precise amount of carbohydrates for your health conditions (like type 2 diabetes) and learn what carbohydrates support weight loss. 

Types of Carbs

As mentioned earlier, the carbohydrate quality or source impacts your health more than a set amount of carbohydrates to eat daily.¹ 

Simple carbohydrates are digested faster than complex carbohydrates, leading to quick-rising blood sugar levels. Complex carbs contain fiber that helps keep you full, support healthy gut bacteria, and stabilize blood sugar levels.²

Refined or simple carbohydrates are associated with increased disease risk, while complex carbohydrates are associated with health and decreased disease risk.^{2, 5, 7, 8} 

Opt for more complex (good) carbohydrates and limit refined (bad) carbohydrates for optimal health and weight loss. 

Complex Carbs

Complex carbohydrates have many health benefits. Complex carbohydrates are made of many glucose units in a more complex chemical structure. They take longer to digest and have a more gradual effect on blood sugars.²

Fiber is a complex carbohydrate that the body can’t digest, but it encourages healthy bacterial growth in the intestines and helps with regular bowel movements.² 

Complex carbohydrates include:

1. All fruits (fresh, frozen, canned in water or juice, and unsweetened dried fruit)
2. All vegetables, including starches like sweet potatoes or corn, and non-starchy types like broccoli, lettuce, and Brussels sprouts. 
3. Lentils, legumes, and beans
4. Whole grains (brown rice, quinoa, oats, whole-wheat bread, and whole-wheat pasta)
5. Bean-based pasta like chickpea, black bean, or lentil pasta
6. Bran products
7. Seeds and nuts like peanuts, chia or ground flax seeds, almonds, and walnuts

Research supports consuming more complex carbohydrates as individuals who do so have a lower risk of heart disease and type 2 diabetes.⁵ 

People who consume more whole grains also have a lower risk of heart disease, diabetes, and some cancers. They also were more likely to have a lower body mass index (BMI) and gain less weight over time.⁹ 

Choose complex carbs and look for high-fiber foods when selecting carbohydrates. 

Simple Carbs

Simple carbohydrates are one (monosaccharides) or two sugar units (disaccharides). They provide quick energy and lead to a rapid rise in blood sugar.² 

Simple carbohydrates include:

• Fructose (found in honey, fruits, and high-fructose corn syrup)
• Lactose (found in milk and milk products like yogurt)
• Sucrose (found naturally in fruits and vegetables, but most commonly table sugar eaten alone or added to sweet foods or baked goods)

Not all simple carbohydrates are unhealthy or harmful. Sugars from fruit, milk, and milk products contain other beneficial components like vitamins, minerals, protein, fat, and fiber. Milk contains protein and fat. Fruit contains fiber.²

Their naturally sweet taste can help you consume less added sugars or refined carbohydrates by satisfying your sweet tooth.

Added sugars are added to foods or drinks (like sugar in coffee, sweet tea, soda, cereal, or baked goods), whereas naturally occurring sugars are found in milk and fruit. 

Refined carbohydrates are simple carbohydrates that should be limited or eliminated from the diet. 

The refined and simple carbohydrates listed below often lack other beneficial nutrients like fiber, protein, vitamins, and minerals. They mainly provide quick fuel, but when not paired with other fiber-rich and protein foods, they result in energy crashes and variable blood sugar levels.

Refined carbohydrates to limit or avoid include:

1. Snack foods like chips, pretzels, and crackers
2. Sugary drinks like sweet tea, soda, sports drinks, fruit punch, juice, flavored milk, and sweetened coffee
3. Desserts like pie, cookies, brownies, and cake
4. Most processed foods like pizza and breaded fried meats
5. White bread, white flour tortillas, rolls, bagels, or buns
6. Baked goods like pastries, donuts, muffins, and cinnamon rolls
7. White pasta like macaroni, spaghetti noodles, and ramen noodles
8. Sweetened breakfast cereal

Diets high in refined carbohydrates are associated with an increased risk for type 2 diabetes.⁵ 

Regular intake of sugar-sweetened beverages is associated with weight gain, risk of type 2 diabetes, heart disease, and some cancers.⁸

Increased sugar intake also leads to dental caries (cavities).² 

Tips for Consuming Healthy Carbs for Weight Loss

If you struggle to lose weight, review your typical carbohydrate choices. 

Consider the following tips to improve your health, stabilize blood sugar levels, and lose weight:

• Aim for a healthy carbohydrate range of 45 to 65% of your total calories. 
• Consuming too many carbohydrates, particularly refined carbohydrates or those with added sugar, can harm one's health and sabotage weight loss efforts. 
• Choose high-quality complex carbohydrate sources like fruits, vegetables, whole grains, nuts, lentils, and beans. 
• The Dietary Guidelines for Americans recommend limiting added sugars from foods like desserts, sweets, and sugary drinks to less than 50 grams (or 200 calories) daily. 
• Start improving one meal at a time. Focus on your dinner carbohydrates for a few weeks, and improve the carbohydrate choices of other meals as you progress. 

Learn More About How to Improve Blood Sugar Health With Signos’ Expert Advice

Making simple changes to your carbohydrate choices can help you lose weight, control your blood sugar levels, satisfy cravings, and improve your overall health. 

Signos’ expert advice can help you make informed choices about food choices to improve your health, manage diabetes, and support weight loss. 

You can learn more about nutrition and health habits on Signos’ blog (written by nutrition and health experts). Take a free quiz to determine if Signos is a good fit for you.

<div class="pro-tip"><strong>Also Read: </strong><a href=how-many-carbs-should-i-eat-a-day-to-lose-weight>How Many Carbs Should I Eat a Day to Lose Weight?</a>.</div>