What’s in Our Food? Understanding Nutrients and How They Fuel Us

Understanding Nutrients and How They Fuel Us

Food is more than just something we eat to satisfy hunger—it’s a powerful mix of chemical compounds that fuels, builds, and sustains our entire body. The same elements found in the stars, the Earth, and towering skyscrapers are also in the meals we eat. Every bite is a collection of molecules that deliver energy, structure, and essential tools for life.

At its core, food is made up of nutrients—chemical substances the body depends on to survive and thrive. These nutrients fall into two main categories:

• Macronutrients – needed in larger amounts, they provide energy and form the building blocks of your body.
• Micronutrients – required in smaller amounts, they support the systems that keep everything running smoothly.

Understanding what’s in our food helps us make choices that support energy, long-term health, and overall wellbeing.

Macronutrients: Fuel and Foundation

Macronutrients are the major components of food that provide energy and structure.

1. Carbohydrates – The Body’s Preferred Energy Source

Found in whole grains, fruits, vegetables, and legumes, carbohydrates are the body’s main fuel—especially for the brain and active muscles. Each gram of carbohydrate provides 4 calories of energy.

• Simple carbs (like glucose and fructose) deliver quick energy.
• Complex carbs (like starch and fiber) provide longer-lasting fuel and/or support healthy digestion.
• • Fiber—though not digested—plays a crucial role in gut health, blood sugar balance, and cholesterol regulation.

Carbohydrates that aren’t used immediately for energy are stored as glycogen for short-term use, or converted to fat for long-term storage.

2. Fats – Energy-Dense and Essential

Fats are the most concentrated source of energy, offering 9 calories per gram. But they do more than fuel us—they help build cell membranes, produce hormones, and support brain health.

• Unsaturated fats (found in nuts, seeds, avocados, and plant oils) are heart-healthy.
• • Omega-3s, a type of unsaturated fat (from flax, walnuts, and algae oil), are vital for reducing inflammation and supporting heart and brain function.
• Saturated fats (found in animal products and tropical oils) may raise inflammation and heart disease risk.

Fats that aren’t immediately used for energy are efficiently stored in the body’s fat cells, where they serve as a long-term energy reserve.

3. Protein – The Body’s Building Material

Proteins are made of amino acids, which are used to build and repair tissues, enzymes, hormones, and muscles. Like carbohydrates, protein provides 4 calories per gram.

Amino acids are either essential (must come from food) or nonessential (can be synthesized by the body from other nutrients). In either case, adequate protein intake is vital so the body can access the full set of amino acids it needs to function properly.

• Plant-based sources include lentils, tofu, tempeh, chickpeas, and quinoa.

Unlike carbs and fat, protein isn’t stored for future use—it’s either used for immediate needs, converted to energy, or stored as fat if consumed in excess.

Micronutrients: The Hidden Helpers

Micronutrients don’t supply energy directly, but they are crucial for nearly every internal process—from metabolism and immunity to bone strength and mood balance.

1. Vitamins – Catalysts for Wellness

Vitamins help the body extract energy from food, maintain organs, and repair cells.

• Fat-Soluble (A, D, E, K) – stored in the body’s fat, so excess can build up.
• • A: vision & immunity (carrots, sweet potatoes)
  • D: bone health (sunlight, fortified foods)
  • E: antioxidant protection (nuts, seeds)
  • K: blood clotting (leafy greens)
• Water-Soluble (B-complex, C) – not stored long-term, so regular intake matters.
• • B vitamins: energy metabolism (whole grains, legumes)
  • C: immunity and skin health (citrus, peppers, berries)

2. Minerals – The Body’s Structural Support

Minerals are involved in everything from fluid balance to oxygen transport.

• Major Minerals
• • Calcium: bones & teeth (leafy greens, fortified milk alternatives)
  • Magnesium: nerves & muscles (nuts, seeds)
  • Potassium: hydration & blood pressure (bananas, potatoes)
  • Phosphorus: energy production (legumes, seeds)
  • Sodium: necessary but often overconsumed (salt, processed foods)
• Trace Minerals
• • Iron: oxygen transport (legumes, leafy greens—pair with vitamin C to enhance absorption)
  • Zinc: immunity & wound healing (pumpkin seeds, beans)
  • Iodine: thyroid function (iodized salt, seaweed)
  • Selenium: antioxidant role (Brazil nuts)

Why It Matters: Eat With Insight

Food isn’t just about calories—it’s a rich, complex mix of compounds that powers every corner of our body. Macronutrients provide the fuel and structure, while micronutrients regulate and fine-tune the machine.

In addition to nutrients, plant foods also contain a wide range of beneficial non-nutrient compounds, such as polyphenols, phytosterols, and carotenoids. While not classified as essential nutrients, these natural chemicals contribute to antioxidant activity, inflammation reduction, and other protective effects in the body.

By understanding what’s in your food, you’re not just eating—you’re nourishing, supporting, and protecting your future self.

Final Thought

What you eat shapes how you feel, function, and live—day after day. The more you understand your food, the more power you have to support your health with purpose and clarity. Every meal is a chance to build strength, prevent harm, and invest in a vibrant future. Choose with care—your body is listening.

Dig Deeper

For a more in-depth exploration of the science behind nutrients and how they fuel the body, check out Chapter 2: “Food Chemistry” in Life in Every Bite: Exploring the Science of Healthy Eating. Learn more about the book