PNP NUTRITION BASICS: Lesson 3 - Macronutrient: Carbohydrates
Understanding Carbohydrates
Carbohydrates are organic compounds composed of sugars, starches, and fiber. Plants produce carbohydrates through photosynthesis, storing them in the form of saccharides (sugars). In the human body, carbohydrates serve primarily as a source of energy. When not used immediately, they are stored as glycogen in the liver and muscles; any excess beyond storage capacity is converted to fat. While the body can generate glucose from non-carbohydrate sources via a process called gluconeogenesis, carbohydrates from whole plant foods remain essential because they also provide fiber, vital nutrients, and health-promoting phytochemicals.
The Glycemic Index (GI)
Understanding the glycemic index (GI) is essential when evaluating the types of carbohydrates you eat. The GI is a scale from 0 to 100 that measures how quickly a carbohydrate-containing food raises your blood sugar levels after eating. Foods with a high GI (70 and above) such as white bread, instant rice, or sugary breakfast cereals, cause rapid spikes in blood sugar. In contrast, low-GI foods (55 or less), like steel-cut oats, sweet potatoes, and most legumes, are digested and absorbed more slowly, resulting in a gradual rise in blood glucose. Medium-GI foods (56–69) fall in between, including options like whole wheat bread or quick oats. This is important for managing energy levels, appetite, and long-term metabolic health. Choosing lower-GI carbohydrates can improve insulin sensitivity, reduce inflammation, and help prevent chronic conditions like type 2 diabetes and heart disease.
While some experts now emphasize the glycemic load (which factors in portion size) for a more complete picture, the GI is still widely used as a helpful reference when selecting carbohydrate-rich foods.
Simplifying Carbohydrates: What You Need to Know
Carbohydrates come in many forms, but what matters most for everyday health and preparedness is how they affect your blood sugar, energy levels, and digestion throughout the day.
Simple sugars are found in foods like ripe fruits, fruit juices, table sugar, and sweetened snacks. These carbohydrates typically rank high on the glycemic index (GI), often between 60 and 100, especially when processed or in liquid form. Because they’re digested and absorbed rapidly, they cause quick spikes in blood sugar, followed by sharp crashes. This can leave you feeling tired, hungry, or irritable shortly after eating. While natural sources like whole fruit are fine in moderation—especially when paired with protein or fat—it’s best to limit added sugars and sweetened products for sustained energy and metabolic health.
Complex carbohydrates are found in whole grains like oats, quinoa, and brown rice, as well as legumes and fiber-rich vegetables. These tend to fall on the low to medium end of the GI scale, typically between 40 and 65, depending on how processed they are. Because they break down more slowly, they help maintain steady blood sugar levels and provide more sustained energy throughout the day. Including these in your meals can help reduce cravings, support metabolic health, and keep you feeling full and focused for longer periods.
Refined carbohydrates include white bread, white rice, crackers, pastries, and many packaged snack foods. These are technically complex carbohydrates, but they’ve been highly processed, stripping them of fiber and nutrients. As a result, they digest quickly and rank high on the GI scale—often 70 or above. Eating refined carbs leads to rapid spikes in blood sugar, followed by a crash in energy, which can result in fatigue, mood swings, and increased hunger shortly afterward. For better energy and health, it’s best to limit refined carbs and instead choose whole, minimally processed alternatives.
Resistant starches are a unique type of carbohydrate that act more like fiber. Found in foods like cooked-and-cooled potatoes, green bananas, lentils, and legumes, they are not fully digested in the small intestine. Instead, they pass into the colon, where they are fermented by gut bacteria. Resistant starches are typically low GI (around 35–50) and promote a slow, steady release of energy. They also support gut health, reduce inflammation, and may improve insulin sensitivity. Including resistant starches in your diet can help you feel full longer, support digestive health, and provide more stable energy throughout the day.
For those focused not only on preparedness but also on overall everyday health, choosing the right carbohydrates means having foods on hand that offer nutrient density, stable energy, and digestive support. Whole grains are a smart staple; they store well, especially when kept in airtight containers or vacuum-sealed in a cool, dry environment. Sweet potatoes, beans, and lentils are also excellent options, as they can be stored dry or canned and provide long-lasting, slow-burning fuel for both daily nutrition and emergency situations.
