Food That Fuels You - Learn About the Body's Energy-Giving Nutrients

Just like a car needs fuel to run, our bodies need energy to function. We get that energy from the food we eat, especially from three energy-giving nutrients:

• Carbohydrates
• Protein
• Fat

These nutrients provide us with energy in the form of calories, which the body uses for everything from movement to powering the brain and internal organs. In this post, you'll learn more about how they work and why it's important to get enough of all three.

Carbohydrates - The Body's Main Energy Source

We often hear about carbohydrates - but what exactly are they, and why do people talk about "fast" and "slow" carbs? Here's what carbohydrates do in the body, which ones to prioritize, and why too much of the wrong type can negatively affect you.

What Are Carbohydrates?

Carbohydrates are one of the body's main nutrients and our fastest energy source. When we eat carbs, they break down into sugar (glucose) in the stomach and intestines. That sugar enters the bloodstream and is used as fuel for muscles and the brain.

• The brain uses almost only glucose as fuel - to think clearly, focus, and remember, it needs a steady supply of energy.
• Muscles rely on carbohydrates during movement – especially during exercise or physical activity. The body can also store carbs as glycogen in muscles and the liver, acting as an energy reserve when needed.

Why Do We Need Carbohydrates?

Carbs are important for:

• Quick energy for the whole body
• Brain function, especially concentration and memory
• Endurance during physical activity
• Maintaining glycogen stores for exercise or stress
• Balancing blood sugar – if we choose the right kinds

Good Sources of Carbohydrates

The best choices are nutrient-rich carbs high in fiber. They provide slower, steadier energy, help you feel full longer, and stabilize blood sugar. Examples:

• Whole grain bread and pasta
• Oats and muesli
• Potatoes, sweet potatoes, root vegetables
• Fruits and berries
• Beans, lentils, and legumes

Tip: Check fiber content when shopping - go for products with more fiber for steadier energy throughout the day.

Fast Carbohydrates - What Are They?

Fast carbs break down very quickly in the body, causing a rapid spike in blood sugar - followed by a sharp drop. This can lead to:

• Energy crashes
• Fatigue and trouble concentrating
• Increased cravings and hunger
• Higher risk of overweight and type 2 diabetes over time

Examples of Fast Carbs:

• White bread
• White pasta (low-fiber pasta)
• White rice
• Soda, candy, sugary drinks
• Pastries, cookies, sweetened cereals

Protein - The Body's Building Blocks

When you hear “protein,” you might think of muscles and fitness - but everyone needs protein, whether they exercise or not. Protein is essential for the entire body!

What Is Protein?

Protein is a nutrient the body uses to build and repair tissues. It acts as a core building material - needed to construct and maintain everything from muscles to skin and hormones. When you eat protein, it breaks down into amino acids - small building blocks used by the body.

• Muscles
• Skin, hair, and nails
• Hormones and enzymes
• Immune system components
• Blood and internal organs

Why Do We Need Protein?

Protein serves many crucial functions:

• Builds and repairs tissue - e.g., muscles after exercise or injury
• Forms hormones and enzymes essential for body processes
• Strengthens immunity - some antibodies are proteins
• Contributes to satiety - keeps you fuller longer
• Provides energy - especially when carbs/fat are lacking

Good Sources of Protein

Protein is found in both animal and plant foods.

• Animal sources (complete proteins): eggs, chicken, meat, fish, milk, yogurt, cheese, seafood
• Plant sources: beans, lentils, peas, tofu, tempeh, soy products, quinoa, nuts, seeds, oats

For vegetarians and vegans: Most plant-based protein sources don’t provide all essential amino acids in one food. Combine foods like beans with rice, hummus with whole grain bread, or lentil soup with oat bread to get all essential amino acids throughout the day.

What If You Don’t Get Enough Protein?

• Muscle loss (especially during weight loss or illness)
• Poor wound healing
• Weakened immune system
• Fatigue and weakness
• Reduced focus and energy

How Much Protein Do You Need?

• Adults: 0.8–1 g per kg of body weight per day
• Active individuals: 1.2–2 g per kg

Tip: Spread your protein intake throughout the day for better satiety, energy, and recovery.

Fat - The Body's Energy Reserve and Vital Building Block

Many people think fat is something to avoid - but it’s actually essential! Fat gives us energy, builds key parts of the body, and helps protect us.

Why Do We Need Fat?

• Provides lots of energy - more than carbs or protein per gram
• Builds cells and hormones necessary for body functions
• Protects vital organs and maintains body temperature
• Essential for brain health - the brain is largely made of fat
• Helps absorb certain vitamins

Types of Fat

• Healthy fats (unsaturated fats): olive oil, avocado, nuts, seeds, fatty fish
• Less healthy fats (saturated fats): butter, cheese, cream, some meats (limit intake)
• Unhealthy fats (trans fats): some processed foods and baked goods (avoid)

Omega-3 – Essential Fatty Acids

Omega-3 is a type of unsaturated fat important for brain, heart, and vision. The best source is fatty fish like salmon, mackerel, and herring. Many people don’t get enough, so consider supplements if needed.

Good Sources of Fat

• Olive oil and canola oil
• Avocados
• Nuts and seeds
• Fatty fish (salmon, herring, mackerel)
• Coconut oil (in moderation)
• Eggs

What Happens If You Don’t Get Enough Fat?

• Deficiency in key vitamins (A, D, E, K)
• Dry skin and hair
• Hormonal imbalances
• Low energy
• Impaired brain function and memory

How Much Fat Do You Need?

• Fat should make up about 25–40% of your total energy intake
• Focus on getting more unsaturated fats
• Limit saturated fats
• Avoid trans fats as much as possible

Final Thoughts

Eating the right balance of carbohydrates, protein, and fat is essential to fuel your body, build strength, and support overall well-being.

• Choose fiber-rich carbohydrates
• Spread your protein intake throughout the day
• Focus on healthy, unsaturated fats – especially omega-3

Small changes in your diet can lead to big improvements in energy, mood, and health. Start today, listen to your body, and enjoy the food you eat!

Want to Learn More?

📘 I’ve written the book Basic Nutrition for a Healthy Lifestyle - an easy-to-understand guide filled with visuals that offers a clear and simple introduction to nutrition.

Click here to get your copy on Amazon!

This book is written under my pen name, Kara Kewenhart.

💚Eat well, feel well,
Karin Kewenter