How to Count Carbs

Medically Reviewed by Jabeen Begum, MD on July 19, 2024
Written by Shawna Seed
8 min read

Carbohydrates -- also called carbs -- are an important energy source for your body. Your digestive system can break them down quickly. They're converted into glucose, or blood sugar. Your body can use glucose right away for energy or store it for later.

If you're trying to stick to a certain diet or lose weight, you may want to restrict your carb intake and make sure you're selecting the healthiest ones. You also may need to limit carbs if you're managing diabetes.

Counting carbs is one way to monitor how many you consume. Carbs are typically measured in grams, which indicates weight.

If you don't have diabetes, your blood sugar level will rise after you eat carbs, but your body's insulin will keep your blood sugar from going too high. 

However, when you have diabetes, your blood sugar can spike too high after you eat carbs because there's an issue with your insulin response.

Type 1 diabetes 

Your pancreas isn't making insulin. To keep your blood sugar levels stable, you need to take insulin. It's important to know how many carbs you're consuming to be able to strike the right balance.

Type 2 diabetes

You're resistant to the insulin your body makes, and you don't have enough in your body to keep your blood glucose at the right level. You need to keep an eye on your carbs as well. 

There are several steps you can take to help count your carbs accurately.

 

When we think of carbs, we often think about bread and pasta. But they're just two sources of carbs. Others include: 

  • Starchy foods
  • Sugars
  • Fruit
  • Milk
  • Yogurt
  • Vegetables
  • Legumes, such as beans and peas

Make sure you count all of your carbs, not just the obvious ones.

Figure out the amount of carbs, protein, and fat you can eat at meals and snacks throughout the day to keep your blood sugar levels steady. 

Experts recommend that you get 45%-65% of your daily calories from carbs. Carbs have 4 calories per gram. So if you eat 2,000 calories a day, you should eat 225 to 325 grams of carbs.

If you're trying to lose weight, you need to burn more calories than you take in. You may want to aim for 100-150 grams of carbohydrates per day.

It can be helpful to break up that total and eat carbs consistently throughout the day.

For instance, adults with diabetes often aim for 45-60 grams of carbs per meal and 15-20 grams per snack. That number may go up or down, depending on how active you are and the medicines you take, so check with your doctor or a registered dietitian.

Carb counting: Sample menu

Here's a sample menu for one day from the CDC. It contains 1,800 calories and 200 grams of carbs.

Breakfast:

  • 1/2 cup rolled oats (28 grams)
  • 1 cup low-fat milk (13 grams)
  • 2/3 medium banana (20 grams)
  • 1/4 cup chopped walnuts (4 grams)

Total carbs: 65 grams, about 4 carb servings

Lunch

  • 2 slices of whole wheat bread (24 grams)
  • 4 oz low-sodium turkey meat (1 gram)
  • 1 slice low-fat Swiss cheese (1 gram)
  • 1/2 large tomato (3 grams)
  • 1 tablespoon of yellow mustard (1 gram)
  • 1/4 cup shredded lettuce (0 grams)
  • 8 baby carrots (7 grams)
  • 6 oz plain fat-free Greek yogurt (7 grams)
  • 3/4 cup blueberries (15 grams)

Total carbs: 59 grams, about 4 carb servings

Dinner: 

  • 6 ounces of baked chicken breast (0 grams)
  • 1 cup brown rice (45 grams)
  • 1 cup steamed broccoli (12 grams)
  • 2 tablespoons of margarine (0 grams)

Total carbs: 57 grams, about 4 carb servings

Snacks

  • 1 low-fat string cheese stick (1 gram)
  • 2 tangerines (18 grams)

Total carbs: 19 grams, about 1 carb serving

Nutrition labels make counting carbs simple. Find the "Total Carbohydrate" number listed on a package's "Nutrition Facts" panel. Then, check the serving size and confirm the amount you can eat. Repeat this step with other foods you plan to eat. When you add all the grams of carbs, the total should stay within your meal budget.

Do dietary fiber carbs count?

A nutrition label will list the grams of "dietary fiber" under the carbohydrate count. That's a type of carb your body can't digest, and it doesn't affect your blood sugar.

You might find a lot of conflicting information about whether those dietary fiber carbs count toward your total. The best advice is to aim for the daily recommended amount of fiber in your diet -- 14 grams per 1,000 calories. Your doctor or nutritionist can give you more information on how dietary fiber affects your carb count.

The size of one serving depends on the type of food. For instance, one small (4-ounce) piece of fresh fruit, 1/3 cup of pasta or rice, and 1/2 cup of beans are each considered one serving. Buy a pocket guide that lists carb counts and portion sizes. Or download an app on your smartphone. Measuring cups and a food scale when you eat at home will help you be accurate.

Fresh foods don't come with a label. You may have to guess the number of carbs they have. A good rule of thumb — each serving of fruit, milk, or starch has about 15 grams. Vegetables don't have a lot, so you can eat more of them. Two or three servings of veggies usually equal 15 grams of carbs.

Some people take insulin to help manage their diabetes. 

Your dose may change, depending on the amount of carbs you ate at a meal and the difference between your target blood sugar level and your actual reading. You'll need to know your "insulin-to-carbohydrate ratio," or the number of carbs one unit of insulin will cover. Generally, one unit of fast-acting insulin covers 12-15 grams of carbohydrates.

Your body can also be more sensitive to insulin changes throughout the day. Stress or how much you exercise also has an impact. It's important to work out a plan with your doctor for how to change your treatment if you need to.

The idea of "net carbs" is controversial. The FDA doesn't define net carbs, and the American Diabetes Association doesn't doesn't use the term.

To get net carbs, you take the total carbohydrates on the nutrition label, then subtract any carbs that come from fiber or sugar alcohols. Those calculations, however, may not be accurate.

The FDA recommends using the "total carbohydrates" number rather than trying to calculate net carbs.

The difference between simple and complex carbohydrates is in the food's structure. 

Simple carbs are found in refined foods. Your body breaks them down more quickly, and they can have a bigger impact on your blood sugar. Often, they don't have much nutritional value. Examples of foods with simple carbs include: 

  • Sugary drinks such as sodas
  • Candy
  • Desserts

Complex carbs have more nutrients. They have both fiber and starch, as well as additional healthy substances such as vitamins, minerals, phytochemicals, and antioxidants. Your body takes more time to break down complex carbs, so they aren't as likely to cause blood sugar spikes. Sources of complex carbohydrates include:

  • Fruits
  • Starchy vegetables such as sweet potatoes
  • Whole-grain bread and pasta
  • Legumes

You count the grams the same whether a carb is complex or simple. But complex carbs have more nutritional value and are better for your blood sugar. They're a healthier choice.

Researchers looking into low-carb diets have come up with some contradictory findings. One problem is that many studies don't follow people for long enough to get a clear picture of how their health has changed, and the definitions of a low-carb diet aren't consistent.

Here are some ways a low-carb diet might improve your health:

Weight loss

A low-carb diet may help you lose weight rapidly. However, your weight loss may be temporary if you don't stick to the diet. In the long run, low carb may not be more effective than other types of diets for weight loss.

Type 2 diabetes management

A low-carb diet can help you control your diabetes. Recent studies show that some people on low-carb diets have been able to cut down their diabetes medications.

In some cases, people on low-carb diets have lowered their blood sugar levels and lost enough weight that their diabetes is considered to be in remission.

Heart health

Some studies have found that a low-carb diet lowers the level of triglycerides, or fat, in your blood while increasing your level of HDL, or "good," cholesterol. Improvements in those numbers lower your risk of cardiac issues. The findings on LDL, or "bad," cholesterol were mixed. Some studies found that a low-carb diet raised your levels of LDL. Others found the diet made little difference in LDL levels.

Counting carbs is a system you can use to manage diabetes or follow a low-carb diet. Carbohydrates are an important source of fuel for your body. They break down quickly to give you energy, but they can also cause your blood sugar to spike. When you have diabetes, your body's insulin response doesn't work well to control blood sugar. Limiting the number of carbs you eat and choosing complex carbs over simple ones may help you lose weight and control your diabetes.

What is the formula for carbohydrate counting? 

One serving of carbs is about 15 grams. Carbs have 4 calories per gram. You should get 45%-65% of your daily calories from carbs.

Is 200 carbs a day too much for people with diabetes?

There's no "right" amount of carbs because everyone is different. Your needs depend on things such as your weight, how active you are, and your age, among other factors. Talk to your doctor or nutritionist about setting your carb target.

How do you calculate the carb ratio for diabetes?

If you take insulin at mealtimes, you'll need to figure out the right dose of insulin for the number of carbs in your meal. This is called the insulin-to-carb ratio. This more complicated version of carb counting is recommended for people who take insulin shots or have an insulin pump. You're more likely to need to do this if you have type 1 diabetes, although some people with type 2 need to do it as well.