Low-carb diets have become popular in recent years — and if you’ve tried one or want to try one, there’s no shortage of places to turn for advice. Whether from health blogs, books, or magazine articles, you can find expert advice on “good” and “bad” carbs, how many carbs to eat, and whether or not to eat carbs at all.
Indeed, paying attention to the type and amount of carbohydrates you consume can have health benefits. Low-carb protocols, such as the ketogenic diet, have caught on, in part, because research shows they may help improve blood-sugar balance, support optimal endocrine (hormone) function, protect against cardiovascular disease and cognitive dysfunction, guard against other chronic conditions like type 2 diabetes and cancer, and support healthy weight loss.
But one of the most useful ways to think about carbohydrates is one of the least talked about: how your body responds to carbs. Most articles give one-size-fits-all recommendations for carb consumption, but the body’s response to carbs is highly individual, based on genetics, the microbiome, adrenal health, and more.
“There’s a lot of genetic variation in how much certain carbohydrates raise insulin,” says functional-medicine doctor Jill Carnahan, MD. (The trigger of excess insulin is one of the negative consequences of eating too many blood-sugar-sabotaging carbs.) “And then there is everything we are finding out about the microbiome. Your unique genetics and unique microbiome are the biggest factors in how you convert food to fuel and keep blood sugar and insulin steady.”
In other words, you may experience health benefits by paying attention to the type and amount of carbohydrates you consume — but you may gain the most benefit by understanding your body’s unique carbohydrate needs and tailoring the amount of carbohydrates you eat to match your individual biochemistry.
“Good” Carbs vs. “Bad” Carbs
The fact that our bodies respond differently to carbohydrates is an important and often overlooked factor, but that doesn’t mean all carbohydrates are created equal when it comes to nutrition. Some carbs, like those found in leafy greens, have more nutritional value than other carbs, like those found in candy bars — no matter how well your body tolerates carbs.
So the first step in taking a smart approach to carbs is to make the distinction between carbohydrates that support health and those that leave the body in a state of nutritional bankruptcy.
Studies show that diets high in refined carbohydrates — like those found in candy, packaged baked goods, processed snack foods, and sweetened beverages — are linked to inflammation, oxidative stress, type 2 diabetes, heart disease, and cancer. On the other hand, diets that are high in nutrient-dense, low-starch, and fiber-rich carbohydrates — like those found in cruciferous vegetables — have been linked to lower risk of cardiovascular disease, cancer, and type 2 diabetes. Think broccoli, Brussels sprouts, arugula, cabbage, cauliflower, and bok choy. Most experts encourage people to eat these vegetables in any amount — and, generally, the more the better.
The wrinkle comes in when we’re talking about healthy carbohydrates like sweet potatoes and brown rice. Yes, they contain phytonutrients and fiber, but they also have more starch than their cruciferous cousins — and hence a greater ability to destabilize blood sugar. And it’s this more pronounced effect on blood sugar and insulin that can make it worth paying attention to how you feel when you consume these foods in certain amounts.
Higher-starch whole foods aren’t unhealthy or “bad,” but because blood sugar and insulin imbalances are believed to be at the root of the health problems associated with the overconsumption of certain carbs — and because higher-starch carbs are more likely to throw a wrench in your blood-sugar balance — you may feel better when you tailor how many of them you eat to your body’s unique needs.
“So many of my patients think of insulin resistance and blood-sugar imbalances as something you have to be concerned with only if you have diabetes or polycystic ovarian syndrome,” says Brooke Kalanick, ND, coauthor of Hangry: Balance Your Hormones and Reclaim Your Joy in 5 Simple Steps. “But when we stabilize blood sugar, we have more energy and fewer cravings and we feel better.”
Some people may discover they need to eat fewer of these types of carbs to improve blood-sugar balance and overall hormone balance. Other people may find that they’d benefit by eating a few more of them. “The fad right now is low carb,” says Carnahan. “But some people need more healthy, whole-food carbs. It depends on the person.”
How to Find Your Unique Carb Tolerance
Kalanick calls the body’s individual response to carbohydrates your “unique carb tolerance.” You can zero in on your unique carb tolerance with some easy, at-home experimentation. Here’s what Kalanick recommends:
- Pick one higher-starch carbohydrate food — think sweet potatoes, legumes, or a grain like brown rice — and eat a half-cup serving of it with a dinner that also includes a healthy protein, a healthy fat, and a good source of fiber. Make note of the amount of healthy fat, protein, and fiber that you eat at this meal.
- Now pay attention to how you feel 30 minutes after eating. If you feel contentedly full at the half-hour mark and you have steady energy, no cravings, and clear thinking, a half-cup is likely a good amount of this particular high-starch carbohydrate for you in combination with the other macronutrients.
- If, however, your brain is feeling foggy and you’re ready for a nap after 30 minutes, or if you’re craving sugar or caffeine despite still feeling full, it can be a sign that a half-cup of this type of carbohydrate is too much for your body.
- To test this theory, repeat the same meal the next day at roughly the same time of day. Eat the same amount and type of healthy protein, healthy fat, and healthy fiber that you ate the day before, but reduce the amount of the same high-starch carbohydrate to one-third cup. This amount might work. If it doesn’t, repeat this process at successive dinners, each time reducing the amount of carbohydrates by a small amount — one bite or two — until you find the amount of carbohydrates that works for you. (Different carb-containing foods can affect people differently, so you may need to do the experiment with each different type of higher-starch whole food that you would like to incorporate into your everyday eating.)
- Now, let’s return to that first meal for a second and imagine a different post-dinner scenario. This time, you eat your initial meal (with a half-cup of carbs) and feel great after 30 minutes, but then you feel insatiably hungry, cranky, or lightheaded at the one- or two-hour mark after eating. This outcome, like feeling crummy at the 30-minute mark, can signal that this type and amount of carbs isn’t ideal for you.
- If you feel symptoms at the two-hour mark, repeat the meal the following night, keeping the amount of carbs the same while slightly increasing the amount of fiber and protein on your plate. If that doesn’t help, try again the next night with the same amount of carbs, slightly more fiber and protein (as on night two), and, this time around, slightly more healthy fat.
- If adding extra fiber, protein, and healthy fat to your plate doesn’t erase your symptoms at the two-hour mark, try a fourth meal with the same foods in the same amounts as your third meal, but this time increase the amount of carbohydrates on your plate by two bites. This advice might seem counterintuitive, but this pattern of symptoms can indicate low cortisol and reactive hypoglycemia, which can be soothed by eating a few more carbohydrates, notes Kalanick.
- There’s one final scenario that might happen after your first test meal (the one with a half-cup of higher-starch whole-food carbs). In this instance, you eat your meal and feel tired, cranky, and awash in sugar and caffeine cravings immediately after eating. If this happens, cut the amount of that particular carb by half at your next meal. If that doesn’t help, repeat the meal again on the third night and keep the amount of carbohydrates the same but increase the amount of fiber.
If the process of tracking symptoms over the course of several meals feels onerous and confusing, or if you try it but it feels like your pattern of symptoms is sending you mixed messages, consider tracking your blood sugar with a glucometer, a small device that you can use at home to test the amount of sugar in your blood, recommends Kalanick. Glucometers are inexpensive and widely available at drugstores and online.
It’s important to remember, however, that this type of carb tracking is meant to be temporary. Once you’ve done the experiment (or used the glucometer) and have more detailed information about your body’s response to carbohydrates, Kalanick recommends letting your body lead the way. The information you glean from the experiment makes an excellent starting place for tailoring your carb intake, but the most important step going forward is to listen closely to your body.
“Sticking to a macro plan despite your symptoms telling you that your hormones hate it can be a real disaster,” says Kalanick. “What works better in the long term is getting feedback from how you feel.”