The Big Three
How Macronutrients Fuel Your Body
What are carbohydrates?
Carbohydrates are a main nutrient in many foods. Your body breaks carbs down into sugar (glucose), which your cells use for energy. [3,2]
There are two main types of carbs: Simple (sugars), and complex (starches, and fiber). [3]
Complex vs. simple carbohydrates
Complex carbohydrates are mostly starch and fiber. They are found in foods like oats, beans, and whole grains. They usually digest more slowly and can help you feel full longer. [4,8]
Simple carbohydrates are mostly sugars. They are found naturally in fruit and milk, and they are also added to many foods and drinks (like soda, candy, and pastries). [3,5,13]
What can be bad about not getting enough carbohydrates?
You may notice:
- Low energy, tiredness, and trouble focusing.
- Harder workouts (your muscles often use carbs for quick energy).
- Constipation if you are also low in fiber (many high-fiber foods are carb foods).
Tip: If you lower carbs, try to keep fiber foods like vegetables, beans, and whole grains. [4]
What can be bad about getting too many carbohydrates?
This depends on the type of carbs. Too many added sugars and refined carbs can cause problems, such as:
- Blood sugar spikes and crashes (feeling hungry again soon).
- Weight gain if you regularly eat more calories than your body uses.
- More tooth decay, especially if you sip sugary drinks often.
Health groups suggest limiting added sugars. The WHO suggests keeping “free sugars” under 10% of daily calories (and lower is even better). [5]
Sugary drinks are linked with higher risk of type 2 diabetes in research reviews. [6]
Eating and drinking sugary items between meals can raise the chance of cavities. [7]
Disease risks that may go down with more high‑fiber, whole‑food carbs
When carbs come from foods like whole grains, beans, fruits, and vegetables, studies link them with:
- Lower risk of heart disease and stroke.
- Lower risk of type 2 diabetes.
- Better digestion and less constipation.
(These are links seen in studies; they don’t prove one food “cures” disease.) [8,9,4]
Food examples (carbohydrates)
Carb amounts below are typical estimates. Brands and recipes can change the numbers. Values are based on USDA FoodData Central. [20]
|
Food |
Typical serving size |
Carbohydrates (g) |
|
Dry oatmeal (rolled oats) |
1/2 cup dry (50g) |
34.0 g |
|
Brown rice (cooked) |
1 cup (202g) |
45.8 g |
|
Whole-wheat pasta (cooked) |
1 cup (151g) |
40.2 g |
|
Lentils (cooked) |
1/2 cup |
~20 g |
|
Quinoa (cooked) |
1/2 cup (93g) |
19.8 g |
|
Black beans (cooked) |
1/2 cup |
~20 g |
|
Sweet potato (baked) |
1 medium (130g) |
26.1 g |
|
Whole-wheat bread |
1 slice |
~14 g |
|
Food |
Typical serving size |
Carbohydrates (g) |
|
Apple |
1 medium (170g) |
26.0 g |
|
Banana |
1 medium (118g) |
27.0 g |
|
Orange juice |
1 cup (8 fl oz / 248g) |
26.0 g |
|
Milk (whole) |
1 cup (244g) |
12.0 g |
|
Yogurt (plain, whole milk) |
1 cup (245g) |
11.4 g |
|
Honey |
1 tablespoon (21g) |
17.3 g |
|
Granulated sugar |
1 tablespoon (13g) |
13.0 g |
|
Regular soda (Coca-Cola) |
1 can (12 fl oz) |
39.0 g |
References
References
Numbers in the text match this list. Accessed February 9, 2026.
-
MedlinePlus (NIH). Nutrition. https://medlineplus.gov/nutrition.html
-
CDC (NCHS). Nutrition (Health, United States): macronutrients and chronic disease risk. https://www.cdc.gov/nchs/hus/topics/nutrition.htm
-
MedlinePlus (NIH). Carbohydrates. https://medlineplus.gov/ency/article/002469.htm
-
MedlinePlus (NIH). Dietary Fiber. https://medlineplus.gov/dietaryfiber.html
-
World Health Organization (WHO). Guideline: Sugars intake for adults and children (2015). https://www.who.int/publications/i/item/9789241549028
-
USDA Nutrition Evidence Systematic Review (NESR). Sugar-sweetened beverages and risk of type 2 diabetes: systematic review (Nov 2024). https://nesr.usda.gov/sites/default/files/2024-11/Sugar-sweetened-beverages_type-2-diabetes-2025DGACSystematicReview.pdf
-
CDC. About Cavities (Tooth Decay). https://www.cdc.gov/oral-health/about/cavities-tooth-decay.html
-
American Heart Association (AHA). Whole grains, refined grains, and dietary fiber. https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/nutrition-basics/whole-grains-refined-grains-and-dietary-fiber
-
BMJ. Whole grain foods and risk of type 2 diabetes: meta-analysis summary. https://www.bmj.com/content/370/bmj.m2206
-
MedlinePlus (NIH). Dietary fats explained. https://medlineplus.gov/ency/patientinstructions/000104.htm
-
American Heart Association (AHA). Fats in Foods. https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/fats/fats-in-foods
-
USDA Food and Nutrition Service (FNS). Dietary Guidelines for Americans (current edition). https://www.fns.usda.gov/cnpp/dietary-guidelines-americans
-
MyPlate (USDA). More Key Topics: Oils, Added Sugars, Saturated Fats. https://www.myplate.gov/eat-healthy/more-key-topics
-
NCCIH (NIH). Omega-3 supplements: what you need to know. https://www.nccih.nih.gov/health/omega3-supplements-what-you-need-to-know
-
MedlinePlus (NIH). Protein in diet. https://medlineplus.gov/ency/article/002467.htm
-
MyPlate (USDA). Protein Foods Group. https://www.myplate.gov/eat-healthy/protein-foods
-
NIH Office of Dietary Supplements (ODS). Vitamin B12 fact sheet for consumers (PDF). https://ods.od.nih.gov/pdf/factsheets/VitaminB12-Consumer.pdf
-
IARC (WHO). IARC Monographs evaluate consumption of red meat and processed meat (Press Release No. 240, 2015) (PDF). https://www.iarc.who.int/wp-content/uploads/2018/07/pr240_E.pdf
-
National Kidney Foundation. CKD Diet: How much protein is the right amount?. https://www.kidney.org/kidney-topics/ckd-diet-how-much-protein-right-amount
USDA. FoodData Central (nutrition database). https://fdc.nal.usda.gov/