Carbohydrate Guide: Complex Carbs vs Simple and What to Eat

Carbs, short for carbohydrate, has unfortunately become a dirty word in some circles in fitness and nutrition, but carbs are important. They are one of three essential macronutrients—carbs, proteins, fats—necessary for complete nutrition and health. 

The type of carbohydrate you eat matters. Complex carbohydrates should be a part of your daily diet because they provide energy, help you manage weight, and even protect against some diseases. Learn more about what complex carbs are, how they differ from simple carbs, and how to choose foods with healthy carbohydrates to fuel your workouts and maintain good health. 

What Are Complex Carbohydrates? 

Complex carbohydrates are large molecules. They consist of sugar molecules strung together in long chains. Another name for this type of molecule is polysaccharide. 

Simple carbohydrates are smaller. A simple carb is made of just one or two sugar molecules. These are also known as monosaccharides and disaccharides. The three monosaccharides found in food are glucose, fructose, and galactose. They combine in different pairs to make the disaccharides sucrose, maltose, and lactose. 

Polysaccharides, or complex carbs, are long chains made up of these simple carbs. Complex carbs in food can be categorized as either starch or fiber. Glycogen is a type of polysaccharide the body uses to store glucose in the liver and muscles. They get broken back down into glucose units for energy as needed. 

Why Are Complex Carbs Part of a Healthy Diet?

Carbohydrates are the primary source of energy in the body. The body can also break down fats and proteins for energy, but preferentially uses carbs to fuel muscles and power the brain. According to USDA current dietary guidelines, carbs should make up 45% to 65% of your calorie intake. (1)

The body digests complex carbohydrates slowly, so they provide lasting, sustained energy. Fiber promotes healthy digestion, controls cholesterol, and makes you feel full so you’re less likely to overeat. 

Another benefit of eating complex carbs is that they are generally found in foods rich in micronutrients. For example, sweet potatoes are packed with complex carbs and also contain vitamins A and C, the B vitamins, iron, copper, manganese, and magnesium. 

What Is the Difference Between Complex and Simple Carbohydrates for Health?

In terms of nutrition, simple carbs don’t have as much to offer as complex carbs. Simple carbohydrates are sugars. They provide the body with energy, but not in the same way. Simple carbs are digested very quickly. 

Sugars provide quick, but short-lived energy. This can be good in some situations. For example, if you are an endurance athlete, simple carbs are better than complex carbs refueling your muscles quickly during an event. You need immediate energy and can’t wait to digest a complex carb. 

If you’re not going to burn sugar off right away, it can be harmful to your health. Simple carbs spike blood sugar. Repeated spikes can lead to type 2 diabetes because the body becomes less effective at lowering blood sugar levels with insulin. 

High blood sugar levels can also harden and narrow blood vessels, increasing the risk for cardiovascular events. 

Weight is another issue. Excess sugar gets stored as fat, which can lead to weight gain. Complex carbs promote stable blood sugar and keep you fuller longer. They aid weight loss and maintenance and also support cardiovascular health. 

Why You Need Complex Carbs for Fitness

There is a lot of emphasis on protein in fitness, which is important, but don’t neglect carbs. Protein is necessary because it allows your body to rebuild muscles bigger and stronger after a strength training workout. Carbs are important for fueling those workouts. 

Carbohydrates are obviously necessary for fueling endurance workout and intense cardio sessions. But, even if you focus mostly on weight training, you still need carbs for energy. If you don’t have adequate glycogen stores, you can’t power through a tough lifting routine. You will reach failure sooner in the workout. Ultimately, you won’t get as much out of your workout without the carbs to fuel it. 

You need carbs in advance of a workout for energy, but carbs are also essential after working out. They provide the energy the body needs to use protein and turn it into more muscle mass during rest and recovery. If you’re trying to eat fewer carbs, try cycling them. Eat more carbs on days when you have tough workouts and less on rest days or active recovery days.

Here is more information about how and why you need to consume carbohydrates when building muscle mass.   

Foods Rich in Complex Carbohydrates

Simple carbs are fine to eat in moderation, but most of your carbs should be complex and come from these food groups: 

• Whole Grains. Whole grains are unrefined and include oatmeal, quinoa, farro, brown rice, barley. You can also enjoy complex carbs in processed foods made with grains like whole wheat bread and pasta. Many cereals are also made with whole grains. 

• Vegetables. Vegetables are good sources of healthy carbs and many micronutrients. Some are starchier, like potatoes, while others have more fiber. Some healthy veggie options include leafy greens, broccoli, carrots, sweet potatoes, squash, cabbage, cauliflower, and zucchini. 

• Legumes. Legumes include beans, lentils, and peas. They are rich in fiber, vitamins, minerals, and protein. Legumes combined with whole grains offer a complete protein, which is useful for vegetarians and vegans. 

• Fruits. Some people tend to shy away from fruits because of the sugar content. But whole, unprocessed fruits are very nutritious. They have fiber, which slows the digestion of the sugar and minimizes blood sugar spikes. Not all fruit skins are edible, but when possible, leave skins on to get more fiber out of your fruit. 

• Nuts and Seeds. Nuts and seeds are real powerhouses with protein, complex carbs, and healthy fats as well as vitamins and minerals. When portioning, be aware that nuts and seeds are relatively high in calories. Some good options to include in snacks and meals include almonds, walnuts, pistachios, chia seeds, pumpkin seeds, and flax seeds. 

Are Simple Carbs Always Bad? 

Of course, sugar is not always bad. Sugar is a source of fuel, but it’s best to limit it to minimize the risk of harmful sugar spikes and weight gain. Watch out for added sugars in particular. This is sugar added to processed food.

Fruit is a good example of natural versus added sugar. A whole piece of fruit naturally contains sugar, but it also has vitamins and minerals as well as fiber that slows the digestion of sugar so there is little or no blood sugar spike. Some fruit juices have added sugar without the benefit of natural fiber, leading to a big sugar spike. 

The American Heart Association recommends that women eat no more than 25 grams (six teaspoons) of added sugar per day. Men should have no more than 36 grams (nine teaspoons). (2) Most food labels now include added sugar, so you can make smarter choices. 

Get Certified to Support Your Clients

Nutrition is a vital aspect of fitness. The ISSA’s Certified Personal Trainer – Self-Guided Study Program includes everything you need to know about training clients, including a foundation in nutrition and how to fuel a tough workout.

References

1. U.S. Department of Agriculture. (2020, December). Dietary Guidelines for Americans 2020 - 2025. Dietary Guidelines for Americans. https://www.dietaryguidelines.gov/sites/default/files/2020-12/Dietary_Guidelines_for_Americans_2020-2025.pdf 

How much sugar is too much? (2023, May 10). www.heart.org. https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/sugar/how-much-sugar-is-too-much