Essential Guide to Carbohydrates

Carbohydrates are controversial among people trying to lose weight. Because individual carbohydrate needs aren’t one-size-fits-all, we’ve put together an informational guide to help you optimize your carbohydrate consumption and choose healthier options, whether you’re trying to lose weight, train for your first half-marathon or anything in between.


Carbohydrates are found in almost all foods and provide 4 calories per gram. As you can imagine, not all carbohydrates are created equal. Different carbohydrates affect your body differently. Carbohydrate-containing foods generally have a combination of two types of carbohydrates: simple and complex.


Simple carbs are also known as “sugar.” It’s made of up to two sugar building blocks connected in a chain. The building blocks can be glucose, fructose and galactose. Because the chains are short, they’re easy to break down, which is why they taste sweet when they hit your tongue. They are also digested and absorbed into the bloodstream quickly.

Foods high in simple carbohydrates include sweeteners (table sugar, syrup, honey), candy, jellies and jams and refined flour. Fruits, vegetables, beans and dairy contain simple carbs, too, but they come with vitamins and minerals, plus fiber and/or protein, so they’re still healthy choices.


Complex carbs can be either “starch” or “fiber.” This carbohydrate is made of three or more sugars connected in a chain; they also contain fiber and tend to come in foods that also contain protein and/or healthy fats, as well as vitamins and minerals. They use the same sugar building blocks as simple carbs, but the chains are longer and take more time to break down, which is why they don’t taste as sweet. The longer chains also slow digestion and thus absorption of the monosaccharides all carbs are broken down into, resulting in a more gradual insulin response, as well as increased satiety. Foods high in complex carbohydrates include bread, rice, pasta, beans, whole grains and vegetables.

Fiber is a carbohydrate, but it doesn’t contribute much to calories because it can’t be broken down and absorbed by the body. Just looking at a nutrition label, you’ll see “dietary fiber” and “sugar” listed under “total carbohydrates,” but the grams never add up. That’s because “total carbohydrates” includes all the types of carbohydrates: sugar, fiber and starch. Sugar and fiber get a starring role on the nutrition label because we care about them. However, starch doesn’t, so if you want to figure out how much starch a food contains, you have to do some math using the following formula:

Total starch (grams) = Total carbohydrate (g) – dietary fiber (g) – sugar (g)


In theory, net carbs are the amount of carbs from your food that can affect your blood sugar levels. The thinking behind net carbs is that insoluble fiber and sugar alcohols (which aren’t digested by the body and don’t enter the bloodstream) shouldn’t count toward your overall carbohydrate intake. The concept of net carbs became popular with the emergence of keto and the Atkins Diet. To calculate net carbs, take the total grams of carbohydrates and subtract the grams of dietary fiber and sugar alcohols.

Net Carbs = total carbohydrate (g) – dietary fiber (g) – sugar alcohols (g)

However, it’s important to note “net carbs” is not a scientifically-defined term and isn’t regulated by the FDA on food packaging. Certain fibers and sugar alcohols, particularly the kinds that are added to processed foods to lower the net carb content, can be at least partially digested and affect blood sugar levels. This is why it’s a good idea to prioritize whole foods in general, and when tracking net carbs. Most countries outside the United States don’t count fiber or sugar alcohols toward their carbohydrate totals on food labels, so they are already tracking net carbs as their standard practice. If you’re tracking net carbs to manage blood sugar, be sure to check with your doctor first.


When it comes to choosing carbohydrates to eat or drink, nutrient-dense sources are the way to go. Here are three rules to help you choose well. One caveat: If you’re a highly athletic person whose desire is to optimize performance, not all of these carb rules apply to you. Read this instead.


Vegetables, beans, nuts and seeds, 100% whole-grain breads, pasta and brown rice should also be included in this rule. These foods are a source of fiber, vitamins, minerals and protein.


Foods like white rice, white bread and traditional pasta are more processed and have healthy nutrients — namely fiber — stripped from them.


Most sources of simple carbohydrates are considered “empty calories” because they’re high in calories but contain little to no micronutrients. They’re a likely culprit when it comes to spiking blood sugar. Fruit and milk are exceptions to this rule because they contain beneficial vitamins and minerals.


To perform basic functions, our bodies need carbs, particularly glucose since it’s the preferred fuel for tissues and organs — and the only fuel for our red blood cells. Without enough carbohydrates, the body breaks down hard-earned protein from muscles and organs to create usable glucose.

The Recommended Dietary Allowance (RDA) for carbohydrates is 130 grams per day. This is the minimum amount required to fuel an adult’s brain, red blood cells and central nervous system optimally. Without enough carbohydrates to maintain your blood sugar in a happy range, the body starts breaking down protein — lean muscle tissue — into glucose to bring blood sugar back to normal.

The RDA of 130 grams carbohydrates per day is a minimum for adult bodies to function properly. Most people need more. According to the Dietary Guidelines for Americans, carbohydrates should make up 45–65% of total calories in our diet. It’s such a big range because our bodies are all different and there’s no one-size-fit-all guidance for the absolute amount of carbs you should consume.

To determine your carbohydrate needs in grams:

  1. Decide what percentage of carbohydrates you need and convert that number to a decimal (for example, 50% is 0.5).
  2. Multiply your “Total Calorie Goal” by the decimal value. This gives you the number of calories from carbohydrates.
  3. Divide that number by 4 to get the grams of carbohydrates.

If you’re not sure what percentage might be most appropriate, read more about how to optimize your macronutrient ranges, or follow this general rule of thumb:

If you’re looking to lose weight, start by keeping your carb intake to 45–50% of your calories. If you’re exercising vigorously for more than 1 hour per day or training for an endurance event like a marathon, you may do better in the 55–65% range.


A traditional “low-carb” diet has 40% or less calories coming from carbohydrates. There’s no denying that many have lost weight and kept it off successfully with this lifestyle. It’s popular for a reason, but it certainly is not the only way to lose weight — and it may not be for everyone.

Eating a low-carb diet (especially a restrictive one) affects your blood sugar levels, which can cause unfavorable side-effects in some people, including being mildly to downright uncomfortable, shakiness, nervousness or anxiety, chills, irritability, lightheadedness, headaches, hunger, nausea, fatigue, blurred vision, lack of coordination and more. These effects and the restriction required can make a low-carb diet difficult to stick with.

If you choose to experiment with eating fewer carbs, here are seven tips to make the transition sustainable:


It may be tough to tell your reaction to low blood sugar since it varies from person to person. When starting a low-carb diet, be on the lookout for the signs and symptoms of low blood sugar (see above). If you experience them, eat a small serving of a carbohydrate-rich snack such as a piece of fruit, some crackers or a slice of bread.


Use the MyFitnessPal app to track your food for at least a week so you have a good understanding of how many grams of carbohydrates you consume daily. Then, slowly step down your carbohydrate intake goal by 5–10% (or about 30–50 grams daily) each week until you reach your desired goal. Remember to increase your fat and protein goals to offset the carbohydrates you’re reducing from your diet.


Tracking net carbs is most beneficial if you’ve decided that a low-carb diet is best for you, says registered dietitian Stepanie Nelson. “It allows for greater food flexibility and makes it easier to hit your fiber goal without going over your carb goal. Fiber is important for cardiovascular health, digestive health and feelings of fullness.” It’s also helpful to track net carbs “if you’re concerned about keeping your blood sugar levels in check, since it can help you keep tabs on the foods that actually impact your blood sugar,” she notes.

Also, you can now track total net carbs in each food, meal and day in the MyFitnessPal app.


Make those carbs count by choosing high-quality carbohydrates — like whole grains, fruits and vegetables — that are packed with fiber, vitamins and minerals. Choose high-quality proteins like eggs, legumes, chicken, tofu and lean cuts of beef and pork. Opt for healthy fats from foods that contain monounsaturated and polyunsaturated fats, such as fish, nuts, avocados and olive oil.


If you’re slashing carbs, you’ll most likely eat (and digest) more protein. For your body to break down and use protein optimally, it’s going to need plenty of water.


If you shed more than 2 pounds per week, be careful. You’re likely losing more water weight and lean muscle than fat. Up your calories to lose weight at a slow but fat-busting pace.


Be honest with yourself: Are you happy eating a low-carb diet? Do you feel good? Our bodies can adapt to eating varying amounts of carbohydrates, but for some, the carbohydrate cravings and blood sugar side effects can be constant struggles. If you feel like your diet is too low in carbohydrates, don’t be afraid to add some back. Aggressively cutting carbs isn’t the only way to lose weight, and certainly isn’t for everyone. Keep this in mind because you’re more likely to stick to your goals, lose weight and keep it off if you feel good and are happy with what goes into your body.