What Are Carbohydrates? Simple vs Complex Carbs Explained

Carbohydrates are one of the three main macronutrients in food, alongside protein and fat.

They are found in a wide range of foods, including:

• grains
• bread
• rice
• pasta
• potatoes
• fruit
• legumes
• milk and yogurt
• vegetables
• sweets and sugary drinks

Carbohydrates are often divided into simple and complex carbs.

That distinction can be useful, but it does not tell you everything about the nutritional quality of a food.

Fiber, processing, portion size and the rest of the food matter too.

What are carbohydrates?

Carbohydrates are compounds made primarily from carbon, hydrogen and oxygen.

The main dietary forms include:

• sugars
• starches
• fiber

During digestion, many digestible carbohydrates are broken down into glucose and other simple sugars that can be absorbed and used by the body. (WHO — Carbohydrate intake for adults and children (2023))

Glucose can be used as an immediate energy source or stored for later use.

Are carbohydrates a macronutrient?

Yes.

Carbohydrates are one of the three major macronutrients:

• carbohydrates
• protein
• fat

Macronutrients are nutrients the body needs in relatively large amounts.

They also contribute energy to the diet.

Carbohydrates provide approximately 4 calories per gram.

Protein also provides approximately 4 calories per gram, while fat provides approximately 9 calories per gram.

What foods contain carbohydrates?

Carbohydrates occur in many different foods.

Common sources include:

Grains and grain products

• oats
• rice
• wheat
• barley
• bread
• pasta
• couscous
• bulgur

Starchy vegetables

• potatoes
• sweet potatoes
• corn
• peas

Fruit

• apples
• bananas
• oranges
• berries
• grapes
• pears
• melon

Legumes

• beans
• lentils
• chickpeas
• peas

Dairy

Milk and yogurt naturally contain lactose, a carbohydrate.

Sweets and sweetened foods

• candy
• biscuits
• cakes
• sweetened cereals
• desserts
• sugary drinks

Carbohydrate foods therefore range from minimally processed whole foods to highly processed products.

What are simple carbohydrates?

Simple carbohydrates are sugars with relatively small chemical structures.

They include:

• monosaccharides
• disaccharides

Common examples include glucose, fructose, sucrose and lactose.

Simple sugars can occur naturally in foods or be added during processing.

Where are simple carbohydrates found?

Simple carbohydrates occur naturally in foods such as:

• fruit
• milk
• yogurt

They can also be found as added sugars in:

• soft drinks
• sweets
• cakes
• biscuits
• sweetened breakfast cereals
• flavored drinks
• many desserts

This is why the label “simple carbohydrate” does not automatically tell you whether a food is nutritious.

An orange and a sugary soft drink both contain simple sugars, but they are very different foods.

What are complex carbohydrates?

Complex carbohydrates consist of longer chains of sugar units.

Starch is the major digestible complex carbohydrate in many diets.

Complex carbohydrate foods include:

• oats
• rice
• bread
• pasta
• potatoes
• beans
• lentils
• whole grains

But again, “complex” does not automatically mean “healthy.”

A highly refined starch can behave differently in the diet from a minimally processed whole grain or legume.

Simple vs complex carbs

The traditional distinction is:

The distinction describes chemical structure.

It does not fully describe:

• fiber content
• micronutrients
• processing
• satiety
• portion size
• overall nutritional value

Are simple carbs bad?

No.

Simple carbohydrates are not automatically bad.

Fruit contains naturally occurring sugars but also provides varying amounts of:

• water
• fiber
• vitamins
• minerals
• other plant compounds

Milk contains lactose but can also provide:

• protein
• calcium
• other nutrients

The nutritional context matters.

Are complex carbs always healthy?

No.

Complex carbohydrates are not automatically healthy simply because their chemical structure is more complex.

Some refined grain products contain starch but relatively little fiber.

Other carbohydrate foods such as beans, lentils and whole grains can provide substantial fiber and other nutrients.

Looking at the whole food is more useful than relying only on the simple-versus-complex label.

What is starch?

Starch is a digestible complex carbohydrate made from many glucose units joined together.

Common sources include:

• potatoes
• rice
• pasta
• bread
• oats
• corn
• beans
• lentils

During digestion, starch is broken down into smaller units that can ultimately provide glucose.

What is fiber?

Fiber is a type of carbohydrate that is not fully digested in the same way as sugars and starches.

Different fibers have different properties.

Fiber can contribute to:

• bowel function
• stool bulk
• satiety
• the structure of foods
• the nutritional value of meals

Fiber-rich foods include:

• vegetables
• fruit
• legumes
• whole grains
• nuts
• seeds

If you want to increase fiber intake, do it gradually and include adequate fluids.

What is sugar?

Sugar is a general term for simple carbohydrates.

Naturally occurring sugars include:

• fructose in fruit
• lactose in milk

Added sugars may include:

• table sugar
• syrups
• glucose
• fructose
• honey
• other sweeteners

The source and the overall food matter.

Naturally occurring sugar vs added sugar

Naturally occurring sugars are part of foods such as fruit and dairy.

Added sugars are incorporated during manufacturing, cooking or preparation.

For example:

• an apple naturally contains sugar
• sweetened apple-flavored candy contains added sugar
• plain yogurt contains lactose
• sweetened flavored yogurt may contain lactose plus added sugar

This distinction is often more useful than simply asking whether a food contains “simple carbs.”

Do vegetables contain carbohydrates?

Yes.

Vegetables contain varying amounts of carbohydrates.

Non-starchy vegetables generally contain less digestible carbohydrate than starchy vegetables.

Examples of non-starchy vegetables include:

• broccoli
• zucchini
• cucumber
• tomatoes
• spinach
• peppers
• mushrooms

Starchy vegetables include foods such as:

• potatoes
• sweet potatoes
• corn
• peas

Both categories can fit into a balanced diet.

Does fruit contain carbohydrates?

Yes.

Fruit contains carbohydrates, primarily from naturally occurring sugars and fiber.

The amount varies between fruits.

Whole fruit also contains water and its natural physical structure, which changes the eating experience compared with drinking fruit juice.

Do beans and lentils contain carbohydrates?

Yes.

Beans and lentils contain carbohydrates as well as protein and fiber.

This is an important reminder that foods do not always fit neatly into one macronutrient category.

Legumes can contribute:

• carbohydrates
• protein
• fiber
• minerals

at the same time.

Does dairy contain carbohydrates?

Milk and yogurt contain lactose.

The carbohydrate content varies depending on the product and whether sugars have been added.

Cheese usually contains much less carbohydrate than milk or yogurt because of how it is produced.

Are potatoes carbohydrates?

Potatoes are a carbohydrate-rich food because much of their energy comes from starch.

But potatoes are not literally “a carbohydrate.”

They are whole foods that also contain:

• water
• potassium
• vitamin C
• other nutrients

Preparation can substantially change the calorie density and nutritional profile.

Is rice a carbohydrate?

Rice is a carbohydrate-rich food.

Most of its calories come from starch.

Different types of rice can differ in:

• fiber
• texture
• cooking characteristics
• micronutrient content

The portion and the rest of the meal matter too.

Is bread a carbohydrate?

Bread is primarily a carbohydrate-rich food, but its nutritional profile depends on the type.

Whole-grain bread can contain more fiber than highly refined white bread.

Bread may also provide some protein and micronutrients.

Are carbohydrates the body's preferred energy source?

Carbohydrates are an important and readily available energy source.

Glucose is used by many tissues.

The body can also use fat and, under some circumstances, amino acids for energy.

There is therefore no need to describe carbohydrates as the body's only possible fuel.

What happens to carbohydrates after you eat them?

Digestible carbohydrates are broken down during digestion.

Many eventually become glucose or other simple sugars that enter the bloodstream.

The body can then:

• use glucose for immediate energy
• store glucose as glycogen
• use it in metabolic processes

Glycogen is stored mainly in the liver and muscles.

What is glycogen?

Glycogen is the stored form of carbohydrate in the body.

The liver stores glycogen that can help maintain blood glucose availability.

Muscles also store glycogen that can be used locally during activity.

The amount stored is limited compared with the body's fat stores.

Do carbohydrates make you gain weight?

Carbohydrates do not automatically cause weight gain.

Body weight changes depend primarily on energy balance over time.

Eating more calories than the body uses can contribute to weight gain regardless of whether those calories come from carbohydrates, fat, protein or a combination.

However, different foods can affect:

• hunger
• fullness
• convenience
• eating speed
• calorie intake

in different ways.

Do you need carbohydrates to lose weight?

Different carbohydrate intakes can be compatible with weight loss.

The key requirement for weight loss is maintaining an energy deficit over time.

Some people prefer a higher-carbohydrate pattern.

Others prefer fewer carbohydrates.

The best approach is one that supports nutritional adequacy, satiety and long-term adherence.

How many carbohydrates do you need per day?

Carbohydrate needs vary depending on factors such as:

• total energy needs
• activity level
• training
• dietary preferences
• health considerations

There is no single carbohydrate amount that is ideal for everyone.

See How Much Carbohydrate Do You Need Per Day?.

Carbohydrates and exercise

Carbohydrates can be particularly useful for physical activity because muscle glycogen is an important fuel source during many forms of exercise.

People doing frequent or demanding training may have different carbohydrate needs from people who are less active.

The appropriate amount depends on the type, duration and intensity of activity as well as overall energy intake.

Carbohydrates and blood sugar

Different carbohydrate-containing foods can affect blood glucose differently.

The response can depend on:

• type of carbohydrate
• processing
• fiber
• portion size
• cooking
• what else is eaten in the meal
• individual physiology

This is another reason the simple-versus-complex distinction alone is incomplete.

What is the glycemic index?

The glycemic index is a system that ranks carbohydrate-containing foods according to their effect on blood glucose under standardized conditions.

It can provide useful information, but it does not describe the entire nutritional value of a food.

Real meals often contain combinations of:

• carbohydrates
• protein
• fat
• fiber

and portion size also matters.

Refined vs whole-grain carbohydrates

The distinction between refined and whole-grain foods can often be more useful than simple versus complex carbohydrates.

Whole grains retain more of the original grain structure.

Examples include:

• oats
• brown rice
• whole-grain bread
• whole-grain pasta
• barley

Refined grains have had parts of the grain removed during processing.

This can reduce fiber and alter the nutritional profile.

Carbohydrates and fiber

Two foods can contain similar amounts of carbohydrate but very different amounts of fiber.

For example, carbohydrate can come from:

• lentils
• whole-grain bread
• fruit
• sugary drinks

The total carbohydrate number alone does not tell you how filling or nutrient-rich the food will be.

Carbohydrates and protein

Many meals work well when carbohydrate foods are paired with a meaningful protein source.

Examples include:

• oats with yogurt or skyr
• rice with beans
• potatoes with fish
• bread with eggs
• pasta with lentils

This can help create a more balanced meal.

Carbohydrates and fat

Fat can also be part of a balanced carbohydrate-containing meal.

Examples include:

• oats with nuts
• bread with seeds
• potatoes with a modest amount of olive oil
• rice with tofu and a sauce containing some fat

Because fat is calorie-dense, the amount can substantially affect the total calories of the meal.

How processing changes carbohydrate foods

Processing can change:

• particle size
• fiber content
• water content
• texture
• eating speed
• convenience
• calorie density

For example, whole fruit, fruit puree and fruit juice can all originate from the same fruit but create different eating experiences.

Similarly, intact grains and highly refined grain products can differ substantially.

How cooking changes carbohydrates

Cooking can soften starch-containing foods and make starch easier to digest.

It can also change water content.

For example:

• rice absorbs water
• oats absorb liquid
• pasta absorbs water
• potatoes soften during cooking

The final weight of a cooked food therefore cannot always be compared directly with the same food in dry form.

Are low-carb diets necessary?

No single carbohydrate intake is necessary for everyone.

Low-carbohydrate diets can suit some people, while others prefer moderate- or higher-carbohydrate eating patterns.

The overall quality of the diet and whether it can be maintained are important.

People with medical conditions requiring carbohydrate management should follow individualized professional guidance.

Should you avoid sugar completely?

For most people, it is not necessary to eliminate every source of sugar.

Naturally occurring sugars are present in nutritious foods such as fruit and dairy.

Added sugars can be consumed in the context of the overall diet, although foods high in added sugar can make it easier to consume substantial calories with relatively little satiety or nutritional value.

What are better carbohydrate choices?

Instead of dividing carbohydrates into “good” and “bad,” consider characteristics such as:

• fiber
• degree of processing
• portion size
• nutrient content
• how filling the food is
• how it fits with the rest of the meal

Useful everyday carbohydrate sources can include:

• oats
• potatoes
• whole grains
• beans
• lentils
• fruit
• vegetables
• rice
• bread
• pasta

The best choice depends on context.

How to build a balanced meal with carbohydrates

A practical meal can contain:

1. a carbohydrate source
2. a meaningful protein source
3. vegetables or fruit
4. some dietary fat

For example, a meal might combine:

• potatoes
• fish
• vegetables
• a small amount of oil

or:

• rice
• beans or tofu
• vegetables
• sauce

There is no requirement for every meal to use exactly the same macro ratio.

Tracking carbohydrates

If you track macros, carbohydrate intake can be estimated from the foods and portions you eat.

The most important sources are often foods such as:

• grains
• bread
• pasta
• rice
• potatoes
• fruit
• legumes
• sweets
• sweetened drinks

But mixed dishes can contain carbohydrates from multiple ingredients.

Photo-based carbohydrate tracking

A food photo may identify visible carbohydrate sources such as:

• bread
• rice
• pasta
• potatoes
• fruit

The difficult part is often estimating portion size and hidden ingredients.

A photo may not clearly reveal:

• sugar in a drink
• flour in a sauce
• sweetened yogurt
• syrup
• breading

AI estimates should therefore be treated as estimates rather than exact measurements.

See Can AI Estimate Macros From a Food Photo?.

Common misconceptions about carbohydrates

“All carbs are sugar”

Carbohydrates include sugars, starches and fiber.

“Simple carbs are always bad”

Fruit and dairy naturally contain simple sugars and can be nutritious foods.

“Complex carbs are always healthy”

Highly refined starches can be complex carbohydrates while containing relatively little fiber.

“Carbs automatically cause weight gain”

Weight gain depends primarily on long-term energy balance.

“You should never eat carbohydrates at night”

The time of day does not make carbohydrate calories fundamentally different.

“Low-carb is necessary for weight loss”

Different carbohydrate intakes can support weight loss when overall energy intake produces a sustained deficit.

“Carbohydrate foods contain only carbohydrates”

Many foods provide several macronutrients. Beans, for example, contain carbohydrates, protein and fiber.

Frequently asked questions

What are carbohydrates in simple terms?

Carbohydrates are a macronutrient found in foods such as grains, potatoes, fruit, legumes, dairy and sweets. They include sugars, starches and fiber.

What is the difference between simple and complex carbohydrates?

Simple carbohydrates have smaller sugar structures. Complex carbohydrates contain longer chains of sugar units, such as starch. The distinction does not by itself determine whether a food is healthy.

What are examples of simple carbohydrates?

Examples include glucose, fructose, sucrose and lactose. They occur naturally in fruit and dairy and can also be present as added sugars.

What are examples of complex carbohydrates?

Examples include starches found in oats, rice, bread, pasta, potatoes, beans and lentils.

Is fiber a carbohydrate?

Yes. Fiber is a type of carbohydrate that is not fully digested like sugars and starches.

Are potatoes carbs?

Potatoes are carbohydrate-rich foods because much of their energy comes from starch.

Is fruit a carb?

Fruit contains carbohydrates, mainly natural sugars and fiber, but it also contains water, vitamins, minerals and other compounds.

Should I stop eating carbohydrates to lose weight?

Not necessarily. Weight loss depends on overall energy balance, and many different carbohydrate intakes can fit a weight-loss diet.

The bottom line

Carbohydrates are one of the three main macronutrients.

They include:

• sugars
• starches
• fiber

The traditional division into simple and complex carbohydrates describes chemical structure, but it does not fully describe food quality.

A more useful approach is to consider:

• fiber
• processing
• portion size
• overall nutrient content
• meal composition
• your individual energy and activity needs

Carbohydrates can come from nutrient-rich foods such as fruit, vegetables, legumes, potatoes and whole grains, as well as from highly processed foods and sugary drinks.

The goal does not need to be avoiding carbohydrates.

It is choosing amounts and sources that fit your overall diet.

This article provides general educational nutrition information and is not individualized medical or dietary advice.

Sources

• WHO — Carbohydrate intake for adults and children (2023)