Lesson 4: Macros 101: How your body uses food

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Nutrition basics: macronutrients + micronutrients

Macronutrients are nutrients you need in larger amounts. They give your body energy and the physical building materials it needs:

• Carbs: 4 calories/gram
• Protein: 4 calories/gram
• Fat: 9 calories/gram

Micronutrients are nutrients needed in smaller amounts. They don't provide energy, but they help you "unlock" energy and support every system in your body:

• Vitamins
• Minerals

Food is not just calories. It's raw material that becomes you.

What happens when you eat

Your body follows this process: digest → absorb → fuel + build

• Carbs are broken down into glucose
• Protein is broken down into amino acids
• Fats are broken down into fatty acids

These building blocks are then sent wherever your body needs them for energy, repair, growth, and maintenance.

Carbohydrates: your body's preferred energy source

What are carbs

Carbohydrates are made of carbon, hydrogen, and oxygen. All carbs are made up of chains of saccharides (or sugar).

Types of carbs

Simple sugars → quick energy

• Monosaccharides: single sugars like glucose, galactose, and fructose
• Disaccharides: pairs of sugars like in milk and table sugar

Complex carbs → steady energy

• Polysaccharides: long chains like oats, potatoes, beans, and whole grains

Your body's preferred energy source

Some cells get "first priority" when glucose is available because they rely on quick and efficient energy:

• Brain cells: Your brain is about 2% of your body weight, but uses 20-25% of your daily energy. Most of that comes from glucose.
• Red blood cells: They can only use glucose because they don't have mitochondria.
• High-demand cells: Many nerve cells and some immune cells rely heavily on glucose because it's quick and efficient.

What happens when carbs are low

When carbs are low, your body switches fuel sources:

• Fat → ketones for energy
• Protein → energy (which can pull amino acids away from building and repair)

This is called metabolic flexibility—your body's ability to switch between fuel sources depending on what's available. Ketones are an alternate fuel that can cross into the brain and be used by your cells.

Fiber: the carb that works differently

Fiber is a type of carbohydrate, but it works differently in your body:

• Soluble fiber forms a gel in your gut that helps with fullness, steadier digestion, and cholesterol support.
• Insoluble fiber adds bulk and helps your digestive system keep things moving.

Why carbs matter

• Preferred fuel for many cells
• Efficient and quick energy
• Support digestion through adequate energy and fiber intake
• Support your brain, energy, and mood
• Spare protein to be used as a building block instead of a fuel source

Carbs aren't good or bad. They're fuel—and your body knows exactly how to use them.

Protein: the building blocks of the body

More than just muscle food

Protein is the raw material that builds your skin, hair, organs, and bones. Inside your cells, protein becomes enzymes that spark the reactions keeping you alive—from digesting food to signaling cell formation.

How it works:

• Builds and repairs every tissue in the body
• Forms enzymes and hormones that regulate body functions
• Supports immune function and recovery from illness and stress

Protein also influences how you feel: it slows digestion and triggers fullness hormones like GLP-1 and PYY.

How protein is digested

Stomach acid → enzymes → amino acids

• Your body absorbs amino acids, not whole proteins
• Amino acids are sent wherever repair, growth, or maintenance is needed. This is happening all day long—even on days you don't exercise
• Using protein for fuel is like burning your furniture to heat your house. It works, but it's not the best idea

Carbs and fats fuel you, protein strengthens you.

How much protein do you need?

Your protein needs depend on your activity level and goals:

Note: This may need to be adjusted based on overall calories. I don't recommend exceeding 40% of your calories from protein.

Fat: structure and stability

What are fats

Fat molecules are made from fatty acids attached to a backbone called glycerol. Your body breaks these apart using bile from the liver and enzymes from the pancreas.

Fat digests slowly, which gives you long-lasting energy and supports fullness.

Types of fat

Saturated fats have no double-bonded carbons

• Found in many animal products, coconut and palm oils

Unsaturated fats have at least 1 double bond:

• Monounsaturated fats are found in olive oil, avocados, and many nuts
• Polyunsaturated fats, found in many plants and fish, include essential omega-3s and omega-6s

Trans fats were banned in 2018. "Hydrogenated oils" are now fully hydrogenated meaning they form saturated fats instead of trans fats.

Why fats matter

• Fat helps you absorb vitamins A, D, E, and K
• It's the main ingredient in the walls of your cells
• It supports hormones and protects your brain and nerves
• Improves satiety and satisfaction of meals

Fat is not just stored energy—it's structure and stability.

Macros work as a team

When you eat these nutrients together, your meals last longer, your digestion improves, your blood sugar is steadier, and your energy feels more predictable. You're also more likely to meet your nutrient needs (including micronutrients).

• Carbs give energy and fiber
• Protein steadies and builds
• Fats help absorption, support building, and satisfaction

What to add

Build meals by including:

• Lean protein
• Fruits and vegetables
• High-fiber carbs
• Healthy fats

Eat what you want and add what's missing.

Micronutrients: your body's helpers

Vitamins + minerals are your body's helpers. Even though you only need small amounts, they make a big difference in how you feel day to day. Your energy, mood, sleep, immunity, and digestion all depend on having enough micronutrients.

Micronutrients help with:

• Immune function
• Bone strength
• Metabolism
• Nerve signaling
• Red blood cell production
• Hormone production
• Wound healing
• Antioxidant protection

Types of vitamins

Fat-soluble vitamins: A, D, E, and K

• Eye health and skin (vitamin A)
• Bone health, mood, and immunity (vitamin D)
• Antioxidant protection (vitamin E)
• Blood clotting and bone repair (vitamin K)

Fat-soluble vitamins need dietary fat in your meal to be absorbed. They can be stored.

Water-soluble vitamins—all the B vitamins and vitamin C

• Energy metabolism
• Nervous system
• Red blood cell production
• Immunity

Water-soluble vitamins aren't stored well in the body. That means you need to eat them regularly.

Minerals: the unsung heroes

Minerals are like the structural and chemical helpers in your body, supporting every system from bone strength, fluid balance, muscle function, oxygen transport, to even mood.

• Iron helps move oxygen through your blood
• Magnesium supports over 300 reactions, including sleep and stress regulation
• Zinc helps your immune system and wound healing
• Calcium supports bones, nerves, and muscle contractions
• Potassium helps regulate fluid balance (along with sodium) and supports heart health

Phytonutrients: plants' natural protectors

They're not vitamins or minerals, and they're something we are still learning about. They help reduce oxidative stress, support cellular healing, and may help protect against long-term disease over time.

Color = Benefits

• Blue/purple: Anthocyanins that support brain health and healthy blood vessels
• Red: Lycopene that supports heart and cell health
• Orange/yellow: Carotenoids that support immunity and vision
• Green: Lutein and other compounds that support eye health and cellular protection
• White/tan: Allicin and similar compounds that support immune function

Your action steps this week

Track 3 days this week to notice patterns:

• Did I include fiber/color at meals?
• Did I include 25+ grams protein at meals?
• Did I include 10+g fat at meals?
• Did I include a carb source at meals?

Weekly goal = skill you practice this week

Choose one area to start with (examples):

• Add protein to each meal
• Add fiber or color to each meal
• Build one balanced plate each day
• Add a carb and fat source to each meal

Minimum habit = simpler version for busy days

Pick one action you can do on your worst days:

• Add a protein-rich snack
• Include one fruit or vegetable at lunch
• Add avocado, nuts, or olive oil to one meal
• Sip a smoothie when solid food feels heavy

Remember: Tracking is optional, but it can be a helpful learning tool. Tracking can help you see if you're lacking in a nutrient (even color). It's not about being perfect; it's about building awareness.

Reflection prompts

At the end of the week, reflect on:

• Which meals helped me feel steady and satisfied?
• What did I notice about my energy when meals were more balanced?
• Which macro was easiest to add? Which one needs support?
• What will I continue next week?

Key takeaway

For sustainable health, eat what you love and add what's missing. Because all foods provide some nutrients and can fit in a healthy diet.

You're not just eating less—you're learning to nourish intentionally.

Next lesson

Lesson 5: Blood sugar balance & gentle meal planning

Learn how to build meals that keep your energy steady and your blood sugar balanced throughout the day.

Download resources

Lesson 4 Worksheet (PDF): Track your weekly focus, minimum habits, and 3-day macro awareness

Macro Awareness Tracker (PDF): Optional detailed tracker for meals, water intake, and movement

See attached files below for worksheets and guides.

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Questions about this lesson? Email care@joinbelle.com

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This information is for educational purposes and does not replace medical advice.