Understanding Carbohydrates: A Comprehensive Guide in 2025

Carbs often get a bad rap. One minute they’re your go-to comfort food, and the next they’re being blamed for everything from weight gain to low energy. Bread, pasta, and sugar are the usual suspects. But here’s the thing: carbohydrates are in way more foods than you might think. And despite what you’ve heard, they’re not the enemy.

Maybe you’ve tried cutting carbs to drop a few pounds fast. It might seem to work at first, but a lot of that early weight loss is just water. Carbs are stored in your body with water, so when they’re gone, the water goes too. That doesn’t mean fat is melting away. It just means your body is storing the carbs in your muscles and liver along with the water. Your body is also probably craving energy.

That’s because carbs are your main fuel source. Your brain, muscles, and even your mood rely on them. In fact, carbohydrates should make up at least 50% of your energy intake – more if you’re active. (And let’s be real, many active people don’t realize how many carbs they actually need to stay energized and feel good.)

With the rise of keto and low-carb everything, it’s easy to get confused. You might wonder whether carbs are friend or foe. That’s where this guide comes in. With insights from our in-house nutritionist, we’ll break down the science behind carbohydrates and offer practical tips for making smarter carb choices. Let’s dive in.

What Are Carbohydrates Made Of? 🔬

Let’s start with the basics. Carbohydrates are 1 of the 3 main nutrients (macros) your body needs to function – along with protein and fat – and they’re your body’s preferred energy source. They're found in everything from fruits and veggies to bread, pasta, and, yes, even that cookie you had with your coffee.

On a molecular level, carbohydrates are organic compounds made up of carbon, hydrogen, and oxygen¹. That might sound like something out of a science textbook, but don’t worry – you don’t need to memorize chemical formulas to understand how carbs work.

Types of Carbohydrates Sources 📊

Not all carbs are created equal. In fact, they come in different forms, and your body processes each one a little differently.

Monosaccharides²

These are the simplest form of carbohydrates – single sugar units like glucose, fructose (found in fruit), and galactose (found in dairy). These are quickly absorbed and used for energy.

You’ve probably seen some of these sugars listed under different names on food labels:

• Dextrose – just another name for glucose

• Honey

• Agave syrup

• Molasses

• Fruit juice concentrate

• Coconut sugar

These might sound “natural” or healthier, but your body breaks them down like regular table sugar. Natural? Sometimes. Processed differently? Sure. But in the end, sugar is still sugar when it comes to how your body uses it.

Disaccharides³

These are 2 sugar units linked together. Common examples include sucrose (table sugar, made of glucose and fructose) and lactose (the sugar in milk, made of glucose and galactose). They are also quickly broken down for energy.

Polysaccharides⁴

These are long chains of sugar units. Think starch, glycogen, and cellulose (a type of fiber). Your body breaks down starches for energy, stores glycogen in muscles and the liver for later use, and uses fiber to support digestion – even though it doesn’t provide energy directly.

Don’t Forget Fiber

Fiber is a type of carbohydrate your body can’t digest. But that’s actually a good thing. It helps with digestion, keeps you full, and supports heart health. Most people should aim for 25–30 grams of fiber per day, but, let’s be honest, many of us fall short. Including more whole foods like fruits, veggies, legumes, and whole grains can help you get there naturally.

Examples of Carbohydrates 🥔🍞🍎

Classification of Carbohydrates 📝

Let’s break carbs down a little more. You’ve already met monosaccharides, disaccharides, and polysaccharides – the scientific names for simple and complex carbohydrates. Now let’s connect the dots between those terms and what’s actually on your plate.

What Are Simple Carbohydrates? 🔗

Simple carbohydrates are the monosaccharides and disaccharides. These are small molecules that your body digests quickly. You’ll find them in:

• Table sugar

• Fruit and fruit juice

• Milk and dairy products

Because they’re absorbed so fast, simple carbs can give you a quick burst of energy – and just as quickly, a crash. They can cause your blood sugar to spike, especially if eaten alone without fiber, protein, or fat to slow things down. That doesn’t mean they’re “bad” – fruit and dairy, for example, also come with vitamins, minerals, and other nutrients. It’s more about balance and there’s nothing wrong with an increase in blood sugar if you’re healthy.

What Are Complex Carbohydrates? ⛓️

Complex carbohydrates are made up of longer chains of sugar molecules. Think polysaccharides like starch. These take longer to digest, giving you a steady release of energy. You’ll find complex carbs in:

• Whole grains (like brown rice, oats, and quinoa)

• Legumes (beans, lentils, peas)

• Vegetables (especially starchy ones like potatoes and corn)

Because they digest more slowly, complex carbs help keep your blood sugar stable and keep you feeling fuller longer – especially when they come from whole, unprocessed sources.

Unprocessed vs. Processed Carbohydrates 🆚

Here’s where things get interesting. Whether a carbohydrate is simple or complex doesn’t always tell the whole story – how processed it is matters too.

Top Quality Carbs to Add to Your Diet ✅

Not all carbs are created equal – some pack way more punch than others. Which carbs give you the best bang for your buck when it comes to energy, nutrition, and satisfaction? Here are some top-quality carbs to include in your meals, why they’re worth it, and how to actually use them.

These carbs are versatile, satisfying, and enjoyable to eat. Including more of them in your meals can help you feel energized and full without the crash you might get from more processed options.

The Importance of Carbohydrates in the Diet

Carbohydrates often get a bad rap, but here’s the truth: your body runs on carbs. Whether you're chasing after kids, lifting weights, or powering through a workday, carbs are your body’s preferred fuel source. Here’s why they deserve a spot on your plate.

1. Carbohydrates Help Preserve and Support Building Muscle 💪

Carbs don’t directly build muscle – that’s protein’s job – but they play a key supporting role. When you eat enough carbs, they’re stored as glycogen in your muscles and liver. This glycogen helps you train harder and recover faster, which ultimately supports better muscle growth over time⁵.

If your glycogen stores are low (say, from skipping carbs), your body may start breaking down muscle protein for energy. This is the opposite of what you want when trying to build or maintain muscle. So while carbs aren’t the star of the muscle-building show, they’re definitely part of the crew.

2. Carbohydrates Are Your Primary Energy Source 🔋

Think of carbs as your body’s go-to energy source. Your brain alone burns through about 20% of your energy intake per day, which is impressive since it only weighs about 2% of total body weight⁶.

Cutting carbs too low can lead to fatigue, brain fog, and irritability, and you may struggle with your workouts. Sure, your body can adapt and use fat or protein for energy, but it’s less efficient – especially if you’re active.

3. Carbs and Gut Health: The Role of Dietary Fiber 🦠

Carbs are also key for gut health, thanks to fiber – a type of carb your body can’t digest but your gut microbiome loves⁷.

Fiber:

• Feeds healthy gut bacteria (especially soluble fiber from foods like oats, beans, and fruit)

• Supports digestion and regularity

• Helps regulate blood sugar

• Can help manage cholesterol levels

Aim for 25–30 grams of fiber per day, and the easiest way to achieve this is to eat a variety of whole grains, fruits, vegetables, and legumes.

How Much Carbohydrate Do You Actually Need?

There’s no one-size-fits-all carb target. There’s no established minimum requirement, but carbs should make up around 45–65% of total calories for most people⁸.

For active people and athletes, more carbs = more fuel. Cutting carbs too low can hurt performance and recovery. In fact, many active folks actually underestimate how many carbs they need to optimize their performance.

If you have a condition like diabetes, tracking carbs can be essential to managing blood sugar. For everyone else, quality is of key importance. Focus on whole grains, legumes, fruits, and veggies.

Harvard’s Healthy Eating Plate is a great way to think about carbs⁹. It suggests filling:

• ½ your plate with vegetables and fruits (yes, both are great fiber sources!)

• ¼ your plate with whole grains like brown rice, quinoa, or whole-wheat bread

No need to count every gram – just focus on building meals around real, minimally processed carbs, and you’ll be fueling your body well.

Debunking Myths About Carbohydrates 🔍

Carbohydrates: Quality vs. Quantity 🆚

When it comes to carbohydrates, what you eat matters more than how much. You might have heard people talk about cutting carbs to get healthier, but the truth is, it’s not about slashing your carb intake – it’s about choosing better-quality carbs more often.

The type of carbohydrate you eat has a bigger impact on your health than the total amount. Whole, unprocessed carbs like vegetables, fruits, legumes, and whole grains come with fiber, vitamins, and minerals that support everything from energy levels to digestion. 

On the flip side, refined carbs like white bread, pastries, and sugary drinks can cause blood sugar spikes without offering much nutritional benefit.

And here's the kicker: a recent review of studies shows that high-quality carbs are associated with a lower risk of disease and better weight management – no drastic carb-cutting required⁸.

Easy Swaps for Smarter Carb Choices ⭐

You don’t have to overhaul your diet overnight. Just start with a few simple swaps to upgrade the carbs you already eat:

These swaps still give you the satisfying carbs your body craves but with longer-lasting energy and better nutrition. It’s not about perfection – it’s about making smart, sustainable choices that work for you.

Carbohydrates & Lifestyle 

🏃 Carbs for active individuals: If you’re hitting the gym, running, or training regularly, carbs are your best friend. They fuel workouts, support recovery, and help maximize glycogen stores so you can train harder and longer. Athletes often need significantly more carbs to maintain energy levels and muscle function¹⁰.

🛋️ Carbs and sedentary lifestyles: If your days are less active, it’s still important to include carbs. Remember to focus on portion size and quality. Whole grains, veggies, and legumes offer sustained energy without overloading calories. The goal: fuel your body, not overfeed it.

A Balanced View of Carbohydrates ⚖️

Carbohydrates aren’t the enemy – they’re an essential macronutrient. When you focus on quality over quantity, carbs can fuel your day, support your workout, and keep you satisfied without the stress. Whole, unprocessed carbs bring fiber, vitamins, and long-lasting energy to the table, making them a key part of any balanced diet.

That said, there’s no one-size-fits-all approach. Your carb needs depend on your activity level, health goals, and how your body feels best fueled. 

Some people thrive with higher-carb meals, especially if they’re active, while others may need to be more mindful – like those managing blood sugar. The key is personalizing your intake in a way that works for you, not following extremes.

FAQ

What is the healthiest carbohydrate to eat?

It depends on your needs and context, but generally, complex carbohydrates are a solid choice. Rather than labeling carbs as “good” or “bad,” it’s better to look at the food they come in. Whole grains, fruits, and vegetables? Great. Cakes and pastries? Tasty, but less nutrient-dense. Focus on foods that offer fiber, vitamins, and lasting energy.

What do carbohydrates do to your body?

Carbs are your body’s main energy source. They fuel your entire body, from the brain and muscles to supporting digestion (thanks to fiber), and help preserve muscle by preventing your body from breaking it down for energy.

What is the number one carb to avoid?

No carb is off-limits in moderation, but limiting refined carbs like cakes, soda, and candy is wise. They offer quick energy but little nutrition. Aim for more complex carbs from plants (think whole grains and veggies) for better energy and satisfaction.

What are examples of bad carbs?

“Bad” is subjective. Fiber-rich complex carbs are great for health, but during a marathon, quick-digesting carbs like gels or juice are more useful. So-called “bad” carbs have their place. It’s all about context and balance, not strict rules.

Can you survive without carbohydrates?

Technically, yes, as your body can make glucose from fat and protein. But eating zero carbs is hard since most foods mix macros (even legumes have carbs). A true no-carb diet means eating only meat, which can have long-term health downsides.

What foods are rich in carbohydrates?

Carbohydrate-rich foods include grains (like bread and rice), fruits, starchy vegetables, legumes, dairy, and even sweets. Choosing whole, unprocessed carbohydrates can help support energy, brain function, and overall health.

References 

1. https://pmc.ncbi.nlm.nih.gov/articles/PMC4224210/

2. https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/monosaccharide

3. https://www.sciencedirect.com/topics/medicine-and-dentistry/disaccharide

4. https://www.ncbi.nlm.nih.gov/books/NBK579972/

5. https://journals.physiology.org/doi/full/10.1152/ajpendo.00004.2012

6. https://pmc.ncbi.nlm.nih.gov/articles/PMC3900881/

7. https://pmc.ncbi.nlm.nih.gov/articles/PMC8153313/

8. https://pmc.ncbi.nlm.nih.gov/articles/PMC5996878/

9. https://nutritionsource.hsph.harvard.edu/healthy-eating-plate/

10. https://pmc.ncbi.nlm.nih.gov/articles/PMC5794245/