For this month’s Ask the Science Team post, we sat down with Dr. Lucas Grant, principal scientist at Unicity, to discuss all things carbohydrates—the benefits and downsides, why you should prioritize complex carbs over simple carbs, and much more. Take a look at the Q&A below to learn more about how carbohydrates work and how they affect your overall health and wellness.
What is a carbohydrate?
A carbohydrate is a molecule that consists of carbon, hydrogen, and oxygen. Carbohydrates are broken down in the body and go through cellular processes to create energy. They are an important part of our diet because they provide the energy we need to function. The brain also needs carbs to run optimally.
However, in our overly processed world, many people eat too many processed carbs, which are not good for us. Broadly speaking, there are two main types of carbohydrates: simple and complex. We should be prioritizing complex carbs.
What is the difference between simple and complex carbohydrates?
Simple carbs consist of monosaccharides (single sugars) and disaccharides (double sugars). Examples of monosaccharides include glucose, fructose, and galactose. Examples of disaccharides include sucrose (aka, table sugar), lactose (milk sugar), and maltose. Sucrose is actually a sugar combination of glucose and fructose. Simple carbs are very easy for your body to digest and absorb, and can result in weight gain if eaten in abundance with not enough exercise.
This is because glucose, of course, is the main energy molecule in humans, and most simple carbohydrates will be broken down into glucose, converted to glucose for use as energy, or stored for later. And this can occur more rapidly than other carb sources, which is why we need to watch our consumption of these.
Complex carbs are made up of oligosaccharides and polysaccharides—longer chains of sugar molecules. Examples include fiber and starch. Generally, complex carbs cause a slower rise in blood glucose than simple carbohydrates, as the chemical bonds between these sugar molecules must be broken before they can be absorbed into the bloodstream. Some types of fiber can swell and form a gel-like structure in the gut, helping to keep you fuller for longer periods of time. This can help with weight management and helps support normal, healthy blood sugar levels.
Humans don’t have the digestive enzymes necessary to break down most fibers, and as a result we aren’t able to digest these in the same way we do other carbs. Our microbiome, the beneficial bacteria in our gut, are predominantly responsible for extracting nutrients from fiber for us and can even convert fiber into other types of very important energy sources for us, which better supports weight management. Amazing!
On the other hand, we do have the digestive enzymes to break down starch ourselves. Starch consists of chains of glucose. As a result, foods that contain starch will typically cause a greater rise in blood glucose than those high in fiber. So opt for high-fiber foods over high-starch foods. And if you’re craving starch, you could also opt for better starch sources. For example, choose whole grain bread over white bread. Or choose food sources with more resistant starch, such as legumes, as resistant starch behaves more like other types of beneficial fiber and aren’t digested rapidly.
Foods high in fiber:
Fruits such as apples, bananas, oranges, raspberries, and strawberries
Nuts and seeds—chia seeds, flax seeds, almonds, pistachios, sesame seeds
Beans, especially navy and white beans
Foods high in starch:
Why are complex carbs better for us?
Simple carbs break down faster and leave you hungry in a shorter period of time than complex carbs do. This may lead to eating more simple carbs, which will turn into fat if not used for energy. Simple carbs can also cause a spike in blood sugar and a subsequent spike in insulin levels, the hormone that helps regulate blood sugar. This is something we want to avoid, because we know that over time, it can cause many undesirable effects on the tissues in the body.
Complex carbs, as mentioned earlier, are digested more slowly than simple sugars, keeping you fuller for longer periods of time. They also supply a steadier release of glucose into the bloodstream, causing a much slower rise in blood sugar than simple carbs. This results in a moderated insulin response.
What is the glycemic index?
Sometimes we start to think that all foods containing simple carbs are bad and that all foods with complex carbs are good, but that’s not always true. Simple carbs found in whole fruits, milk, and other generally healthy foods contain very important vitamins, minerals, and other nutrients. The foods we should be avoiding are processed foods, like sugary drinks and candy.
While it’s true that complex carbs are better for us, we still have to watch out for complex carbohydrates that are refined and processed, meaning a lot of nutrients like fiber, minerals, and vitamins are removed. This includes white bread and white rice.
This is where the glycemic index is helpful. It rates how “healthy” a carb is going to be for you. Foods are given a value to indicate their effect on blood glucose (sugar) relative to the effects of pure glucose. A higher number indicates the food would cause a larger spike in blood glucose. A lower number indicates the food has a smaller or slower effect on raising blood glucose.
For better health, you should select foods with a lower glycemic index. These are often whole foods high in fiber, like apples, beans, lentils, and broccoli. High-glycemic index foods often include foods that are easily and quickly digested, like cookies, cake, and French fries, but there are others that might surprise you. Sweetened dairy products like yogurt, fruits like watermelon and pineapple, and even some whole-wheat breads have a high glycemic index.
Here are some easy swaps you can make for a more controlled blood glucose response (and to avoid that large glucose spike followed by a sugar crash):
Instead of white rice, eat brown rice
Choose multigrain bread instead of white bread
Opt for broccoli or leafy greens over corn
How do I get more of the right carbs in my diet?
To make sure you get the most out of your carbs, start the day with whole grains and use whole or multigrain breads for snacks and lunches. Check the ingredients list on your cereal or bread and make sure whole grain is listed first.
Another easy way to ensure you’re getting enough of the right carbs is to keep the skins on when eating vegetables and fruits. The peels are generally very high in nutrients. For example, a whole apple contains up to 332% more vitamin K and 115% more vitamin C than a peeled apple. These peels typically contain more fiber, too.
What kinds of foods should I avoid?
Avoid anything with lots of added sugars, including soda, baked treats, and fruit juices. Also avoid eating an excessive amount of refined grains such as white bread, white rice, pasta, and crackers.
How many grams of carbohydrates should I eat per day?
According to the Dietary Guidelines for Americans, the average adult should aim to consume somewhere between 900 to 1300 calories (45–65% of calorie intake) from carbs per day.
As a general rule, you should fill up around half to two-thirds of your meals with healthy carbs. A lot of those should come from vegetables or higher-nutrient carbs like beans, brown rice, or quinoa.
Take a look at the “total carbohydrates” section on nutrition labels of foods you eat regularly. Total carbs are broken down into sugars and fibers. Most people don’t get enough dietary fiber, so try to focus on foods with high fiber content and avoid those with added sugars.