As a health coach, one of the most common questions I get asked is whether carbs are good or bad for you. It’s a question that is so open to interpretation that dozens of books and hundreds of scientific articles have been written on the subject. In this post, I’ll suss out the known facts about carbohydrates and give you the straight scoop.
First, it’s important to distinguish between the two common definitions of the term “carbs.” On the one hand, you have the scientific definition: a carbohydrate is a macronutrient consisting of carbon, hydrogen and oxygen atoms. The various combinations of those elements create different kinds of carbohydrates (simple sugars, starches, complex carbohydrates, etc.), which the body processes in different ways. The second definition is the one more commonly used to refer to that category of foods that derive most of their calories from carbohydrates. I’ll spend a few sentences talking about the scientific use of the term and the rest of the post talking about the more common one.
According to the to the National Institutes of Health, carbohydrates (the scientific definition) are the body’s most important source of energy. As I mentioned in my post about sugar, the brain uses glucose as its primary source of fuel and it needs a ready and constant supply of it in the blood stream because it cannot store glucose the way muscles can. It is estimated that the average adult brain requires about 420 calories-worth of glucose every day. Not only that, but glucose is the only source of fuel for several crucial organs including the kidneys, the lens and cornea of the eye, the red blood cells, and the testes. It’s important to note, however, that not all the glucose our bodies require needs to be ingested as the macronutrient “carbohydrates” – our bodies can convert protein (and some fatty acids) into glucose during a process called gluconeogenesis. That’s not the most efficient way to fuel the body, but it works.
Now let’s get down to brass tacks and turn to the more common use of the word carb: the one that refers to that class of foods that get most of their calories from (the scientific definition of) carbohydrates. These foods cover a broad range across the typical human diet and include things like fruits, vegetables, legumes, breads, pastas, desserts and refined sugars, and many others.
Knowing this, you can see that there isn’t a simple answer to my clients’ question about whether carbs are good or bad. Some carbs are nutrient-dense, high in heart-healthy fiber, a good source of plant-based protein and relatively low in calories. Whole, unprocessed fruits, vegetables and legumes fall into this “A” carb category. Adding more of them to your diet is a great idea not only for weight loss, but also for boosting your immune system, reducing inflammation and possibly even fighting cancer.
Falling a bit further down the “healthiness spectrum” are whole grains and healthier versions of minimally processed foods from the “A” carb list (think tempeh, tofu, 100% whole grain breads and pastas). These foods tend to have fewer nutrients than the healthy carbs, but they still provide some very important ones, and the way your body digests and process these “B” carbs doesn’t place undue strain on the body’s vital organs. A word of caution, though – these carbs tend to be much higher in calories per serving than the “A” carbs, so add them to your diet in moderation. Also, these carbs taste kind of bland on their own, so we tend to dress them up with unhealthy additions – butter or margarine on bread, high-sodium sauces on pasta, rice and tofu, etc.
“C” carbs are those that are more highly processed, but which still retain some nutritive value. Canned fruit, white rice, bread, tortillas and pasta, juices and fruit or vegetable-based sauces (tomato, for example) are some examples. Here you’re getting a lot of calories, and mostly in the form of simple sugars, without getting a lot of nutrients. Often, these foods are also processed with other unhealthy additions, like preservatives, added fats and sodium. (In the case of 100% vegetable juices and sauces made from scratch, the nutrient value is higher, so as long as the sodium content isn’t overly high, these are actually probably “B” carbs.)
“D” carbs are basically junk food, and they are actually “F” carbs when consumed more frequently than once or twice per week. The only reason they don’t get a failing grade is because there is some “substance” paired with the sugar/fat/sodium. Don’t kid yourself, though, regularly indulging in these carbs is just as bad as choosing carbs on the “F” list. Chips, muffins, donuts, cookies and candy are a few examples. They don’t offer your body anything good, and there is plenty that’s bad for you. Ironically, most of the calories in these “carbs” are often from fat, with processed flour and/or sugar just holding it all together.
“F” carbs work quickly to disrupt your body’s metabolic system. The body is ill equipped to break down these foreign “foods,” resulting in a number of toxic byproducts. Liver disease, kidney failure and diabetes are serious risks if you consume “F” carbs on a regular basis. These include regular sodas, fruit juice with added sugar, and all sweeteners including natural ones (again, see the article on sugar for more details). Basically, adding a sweetener to your coffee or cereal is like putting a little spoonful of poison in it. If you’re careful about the rest of your diet, then a small amount of these won’t kill you, but they certainly aren’t helping you in any way at all.
What about booze? With the exception of some beers (and of course mixed drinks with fatty or sugary additions), most alcoholic beverages derive the majority of their calories from alcohol. If I were to put them in a category, though, I’d say that your first serving is a “D” and anything over one gets an “F.”
To be healthy, to fuel your body for sport and to manage your weight, most of your food should be of the whole variety, with an emphasis on vegetables, fruits and lean proteins. Simply put, carbs are only as good or as bad as the choices you make.