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As many of you know, carb counting is a way of predicting the impact of different foods and drinks on blood sugar. Some PWDs (people with diabetes) use carb counting to guide them in dosing their insulin. For others, carb counting is their primary therapy, as they use it to match their sugar intake to what their bodies can handle.

Given that all PWDs can benefit from carb counting, we’ve put together this review of the basics, plus a rundown of useful tools and updates on what’s new in the carb counting universe.

First, let’s begin with a primer on what the idea of “counting carbohydrates” is all about…

Carbohydrates (lovingly referred to as “carbs”) are the sugars found mainly in grains, fruits, dairy products and sweets. This includes all the obviously sugary foods like fruit (in any form), candy, baked goods and sugar itself. This also includes all starchy foods like pasta, potatoes and rice. These break down to glucose in your body, and are used by the body for basic energy. But people with diabetes have trouble metabolizing these foods, and too much of them can spike the amount of glucose flowing through your blood.

Note that even green vegetables contain a small amount of carbs, and there are many “hidden carbs” in things like savory sauces, which are often more sugar-based than you might expect.

For anyone with diabetes or pre-diabetes, carbs are the most important element of food to pay attention to, as they have the biggest impact on blood sugar levels.

To count carbs for any given meal, you need two pieces of information: How many carbohydrates are in each food and drink item, and a pretty accurate estimate of the amount of each food you will eat.

Luckily, food scientists have already figured out how many carbs are in pretty much every food and drink on the planet, so it’s easy to look up in a book, an app, or online.

For packaged foods, you can look at the Nutrition Facts label (which recently got a facelift). Just be alert to the fact that many packages of food we regard as a single serving—such as small bags of chips and cans of energy drinks—actually contain multiple servings.

This is because the baselines are calculated for “standardized” serving sizes, which are not necessarily what people really eat, nor a recommended healthy portion. So you’ll need to calculate for your actual portion size—a task that can be simple or complex.

For example, if the little bag of Fritos in your sack lunch says there are 15 carbs in a serving, and that there are three servings in the bag, you know that you will consume a total of 45 carbs if you eat the whole bag. Or if you want to limit yourself to 15 carbs, you’ll need to stop after eating just a third of the bag.

A more complex, but more precise approach is to break the baseline down into its per-gram count, measure the portion you’re going to eat or drink, and then multiply your portion by the per-gram count. Take Raisin Bran, for example. The Nutrition Facts label shows it has 46 carbs in a 59-gram serving. If you divide the carbs by the serving size, you’ll find it has 0.78 carbs per gram. So if you eat a small bowl of this cereal weighing only 35 grams, the carb count for the bowl (before adding the milk) would be 35 x 0.78, or about 27 carbs. Don’t fret about the math; there’s an app for that. Lots of apps, in fact. More on those in a bit.

Virtually all foods and most drinks (excluding water) have some carbs. With drinks, carbs are highest in sodas, fruit juices, and milk. Carbs are lowest in vegetable juices and wine. With food, carbs are the highest in “white” foods: breads, pastas, potatoes, rice, and sugary deserts, and lowest in non-starchy veggies like broccoli, lettuce, and tomatoes—and in lean meats.

In the past, it was recommended that fiber be subtracted from the carb count, to create a “net” impact carb count, but this recommendation was dropped by the American Diabetes Association (ADA) in 2014, due to the fact that it’s “often difficult to discern the independent effect of fiber.”

Historically, meat was viewed as having so few carbs that it wasn’t even included in carb counts, but that’s changing, especially for PWDs who are dedicated to eating low-carb.

Gary Scheiner, renowned Certified Diabetes Educator and author in Pennsylvania, explains that for people with diabetes on ketogenic diets, or eating very low-carb meals, he now teaches them to count half the protein grams as carbs.

In addition to counting protein, the latest dietary advice from the ADA, their Consensus Report on Nutrition Therapy for Adults with Diabetes and Pre-diabetes, also recommends considering the impact of fat, although no specific guidance is provided in to how to go about doing that.

Does this elevate carb counting to an unmanageable level of complexity? Certified Diabetes Educator and nutrition author Hope Warshaw acknowledges that counting carbs — and now assessing protein and fat — can be “arduous and time consuming.” So much so that she advises people with diabetes who take mealtime insulin to simply log their glucose levels after eating, and take notes of the reaction — when and for how long — following different combinations of food. Then with notes and experience, PWDs can act on those observations. So if for example you note that your favorite burrito dish typically makes your blood glucose level rise 60 points after an hour and a half, you can take that into account for either insulin dosing or post-meal exercise.

“We all know that much of diabetes management is trial and error,” Warshaw says, “and this is no different.”

For people with type 2 diabetes on oral medications, carb counting is an effective way to limit meals to the amount of sugar that their bodies can tolerate, by tracking carbs and staying within a “carb budget” calculated with help of their healthcare team.

For people with type 1 diabetes taking rapid-acting insulin at meal times, carb counting is an especially powerful tool because it allows optimization of the insulin dose for each meal.

It starts with an insulin-to-carb ratio, or I:C ratio. This number defines how much insulin your body needs to properly absorb carbs. The ratio is expressed as 1:X, where the 1 stands for one unit of insulin, and the X for the number of carbs 1 unit will “cover.” So if one unit of insulin is enough to cover 10 grams of carbs for you, your I:C ratio would be 1:10.

Your I:C ratio is normally customized for you by your medical team, after a series of “basal tests” that check what happens to your blood sugar levels with and without food in your bloodstream. If you want to explore on your own, Roche Diabetes offers a handy worksheet to test your I:C ratio.

Using the I:C ratio is not as confusing as it sounds…

Let’s say you’ve added up the carbs from each element of your meal and arrived at 68 grams. To figure out how much meal time insulin to take, you simply divide the carbs by your I:C ratio’s X number. If yours were 1:12, you would divide the 68 carbs by 12. In this case, the result is 5.7, and that would be your insulin dose for the present meal.

How easy was that?

If you use an insulin pump, it’s actually possible to take exactly 5.7 units. For PWDs using insulin pens with half-unit capabilities, the dose would be rounded to the nearest half-unit — 5.5 units in this case. For those using disposable insulin pens with only full-unit dosing capabilities, the dose is rounded up to the nearest full-unit, in this case 6 units.

Pretty cool, huh? But of course, the success of carb counting relies on the accuracy of the carb count. Are there any tools to help with that? Of course there are!

Despite our current cultural fondness for having everything on our mobile phones, sometimes a simple printout of carb baselines taped to the inside of your kitchen cupboard or a pocket-sized booklet kept in your glove box is hard to beat when it comes to fast, convenient carb lookup.

Beyond a food database, the key tool for counting carbs is a means for measuring portion sizes. A good old-fashioned Pyrex measuring cup works great for liquids, and sets of smaller spoon-like nesting measuring cups are great for measuring rice and pasta side dishes. Some people keep an extra set in the cupboard, next to these food items or their breakfast cereal, for example, for convenient meal time measuring.

Going up a notch in technology, a nutrition scale is a quick and accurate way to determine portion size. Get one with a “tare” function that lets you zero-out the scale with the weight of the plate or container on it, so that you’re only weighing the food. Many nutrition scales even come pre-programmed with data on hundreds of fresh fruits and vegetables, allowing you to weigh and get a carb count all in one step simply by entering the code for the food you’re weighing.

While the “fully automatic carb analyzer” app is yet to be invented (darn it), there are a growing number of apps that can help you better gather, crunch, and manage the data surrounding carb counting.

Some are databases, some are tracking systems, most are a mix of both. The following get top marks from users:

  • Foodvisor, that uses your smartphone’s camera to help
    you estimate portion size
  • Daily Carb Pro, an app that lets you set a “carb
    budget” and track it throughout the day
  • My Fitness Pal, one of the world’s most widely
    used fitness apps, which includes a comprehensive food database and numerous tracking capabilities
    ranging from food intake to step counting
  • Calorie King Food Search, a carb database that includes menu
    items from 260 national restaurant chains; for basic foods, this app lets you
    customize your portion size, and it crunches the math for you

So now that you know how to count your carbs, how many should you be eating?

There’s no one standard answer to this question. General national dietary guidelines suggest between 225-325 carbs a day, taking in roughly 45 to 60 grams of carbs per meal.

People on low carb diets, like Atkins, limit carbs to between 20-100 total carbs per day, which comes out to less than 30 grams per meal. It really depends on the mix of your age, health, weight, gender, and medications. Ask your medical team what’s right for you.

Ironically, those PWDs who use mealtime insulin can theoretically tolerate higher-carb meals than PWDs who don’t, because they can “dose for it.” Blood sugars will be more variable with high-carb foods, making diabetes management tricky, but taking insulin at least provides an immediate mechanism to offset the sugar spike — which is more difficult to do with oral medications.

Meanwhile, those who don’t take insulin will almost always experience elevated blood sugar after eating — and the more carbs, the higher the post-meal sugar level.

Generally speaking, lower carb meals seem to be the trend in the latest guidelines for people with diabetes. The new ADA Consensus report, while admitting that “carbohydrate intake required for optimal health in humans is unknown,” goes on to note that reducing carbs has “demonstrated the most evidence” for improved blood glucose levels in PWDs. The ADA also points out that lower carbs can “be applied in a variety of eating patterns.”

So what does it take to master carb counting? Not much really, just the correct tools and the discipline to use them on a regular basis. It is easy to make mistakes, however, so don’t beat yourself up for under- or over-estimating at any given meal. The idea is to keep records so you can learn how to best handle that food next time around.

Of course, like anything else, it is possible to take carb counting to the next level, using technology like continuous glucose monitors (CGM) to gain a deeper understanding of the impact of various sorts of carbs — as well as considering eating times, frequencies, exercise, the size of the meals, and more.

But any level of carb counting — apprentice, journeyman, or master — is better for all PWDs than none at all.

This article has been medically reviewed by Marina Basina, MD, on 7/11/2019.