Macros 101: What, Why, and Who It’s For
From fitness influencers touting their daily macro splits to apps that count every gram you eat, macronutrient tracking has become a modern-day nutrition obsession. But while tracking macros may seem like a recent trend, the science behind macronutrients—and the idea of monitoring them—has been evolving for over a century.
At its core, macro tracking is about understanding the fuel your body runs on. Proteins, carbohydrates, and fats aren’t just “calories” or numbers on a nutrition label—they’re biologically essential nutrients that play distinct and powerful roles in your physiology.
Proteins are the building blocks of your muscles, enzymes, and immune system.
Carbohydrates fuel your brain, red blood cells, and most of your high-intensity movements.
Fats are vital for hormone production, cell membrane integrity, and long-term energy storage.
The balance of these macros influences everything from body composition to blood sugar regulation, mental clarity, athletic performance, and even longevity. When we adjust how much of each macro we eat, we can strategically impact how our bodies look, feel, and function.
Research shows that understanding macronutrient intake—not just calories—is a major factor in achieving specific goals like fat loss, muscle growth, and metabolic health. For example, studies have shown that increased protein intake helps preserve lean muscle mass during a calorie deficit【Morton et al., 2018】, while balancing carbohydrate and fat intake can support better energy levels and hormone regulation depending on the individual.
But here’s the twist: despite all the benefits macro tracking can offer, it isn’t always necessary—and in some cases, it may even do more harm than good. This blog explores the science, origins, pros and cons of tracking macros, who it’s ideal for, who should skip it, and how to calculate your own if you decide to try.
🥦 What Are Macronutrients?
Macronutrients—commonly shortened to macros—are the primary nutrients your body needs in large quantities to survive and thrive. They provide energy (calories), but more importantly, they serve as the raw materials your body uses for every major function: movement, repair, growth, hormone production, and even thought.
There are three essential macronutrients: protein, carbohydrates, and fats.
🥩 Protein – The Builder
Calories per gram: 4 kcal
Primary function: Repair and build tissues, produce enzymes, neurotransmitters, and hormones
Protein is made up of amino acids, nine of which are essential (meaning the body can’t make them on its own). When you eat protein, your body breaks it down into these amino acids and uses them to:
Build and repair muscle, skin, hair, nails, and internal organs
Support immune function through the creation of antibodies
Produce enzymes that drive chemical reactions in the body
Regulate hormones like insulin and growth hormone
Synthesize neurotransmitters like serotonin and dopamine
While protein can be used for energy in extreme cases (like starvation or very low-carb diets), the body prefers to use it for structure and function.
📚 Evidence: Protein intake of ~1.6–2.2 g/kg of body weight has been shown to be optimal for maintaining or building lean mass in resistance-trained individuals【Morton et al., 2018】.
🍞 Carbohydrates – The Preferred Energy Source
Calories per gram: 4 kcal
Primary function: Provide quick and efficient energy
Carbohydrates are broken down into glucose, which your body uses for:
Brain and nervous system function – The brain consumes ~120g of glucose per day and cannot function properly without it
Fueling exercise, especially moderate to high-intensity training
Regulating hormones like insulin and leptin (which help control metabolism and hunger)
Glycogen storage – Excess glucose is stored in your muscles and liver for future energy use
When you don’t eat enough carbs, your body must convert protein or fat into glucose via a process called gluconeogenesis—which is metabolically expensive and not ideal long-term.
📚 Evidence: Athletes and active individuals benefit from consuming carbohydrates to replenish glycogen stores, reduce fatigue, and improve performance【Thomas et al., 2016】.
🥑 Fat – The Essential Hormone Helper
Calories per gram: 9 kcal
Primary function: Hormone production, cell membrane integrity, brain health, and long-term energy
Fat gets a bad rap, but it’s absolutely essential:
Forms the structure of all cell membranes
Insulates and protects organs
Is required to absorb fat-soluble vitamins (A, D, E, K)
Cholesterol and fatty acids are the raw materials for hormones like estrogen, testosterone, cortisol, and progesterone
Omega-3 fatty acids (from fish, chia, flax) are critical for reducing inflammation and supporting brain function
Certain fats—like trans fats—are harmful, but unsaturated fats (from nuts, seeds, fish, olive oil) are linked to better heart and metabolic health.
📚 Evidence: Low-fat diets (<15% of total calories from fat) have been shown to reduce testosterone levels in men and may negatively impact female reproductive hormones【Volek et al., 1997; Wu et al., 2021】.
🍷 What About Alcohol?
Calories per gram: 7 kcal
Primary function: None (it’s not a macronutrient, just an energy source)
Alcohol provides calories but no essential nutrients. The body prioritizes metabolizing alcohol over other nutrients because it views it as a toxin. Regular or excessive intake can interfere with fat metabolism, blood sugar regulation, sleep quality, and nutrient absorption.
📜 A Brief History of Macros and Tracking
The idea of categorizing food based on its macronutrient content—proteins, carbohydrates, and fats—originated in the early 19th century, when scientists began studying how food fuels the human body. One of the most influential figures was Justus von Liebig, a German chemist considered the father of modern nutrition. In the mid-1800s, Liebig proposed that food should be broken down into three core components: protein for muscle and strength, carbohydrates for fuel, and fat as a secondary energy source. His work laid the foundation for nutritional biochemistry as we know it today.
As food science advanced into the 20th century, these categories became more standardized, particularly with the creation of national dietary guidelines and food labeling systems. However, macro tracking in the sense we know it—using specific numbers to manage physique or health goals—wasn’t mainstream yet.
💪 From Bodybuilders to the Masses
Macro tracking first gained traction in the 1970s and 1980s, especially in the world of bodybuilding and competitive sports. Athletes seeking peak performance and optimal body composition began carefully manipulating their intake of protein, carbs, and fats to:
Build muscle during “bulking” phases
Shed fat while preserving lean mass during “cutting” phases
At this time, tracking macros was manual—people used food composition books and hand-written journals to log every gram. It was time-consuming, often inaccurate, and only accessible to the most committed athletes.
📱 The Tech Boom: When Macro Tracking Went Mainstream
Everything changed with the rise of smartphones and health tech in the late 2000s. The launch of MyFitnessPal in 2009 was a game-changer. For the first time, everyday people could:
Access a huge food database
Log meals in seconds
Automatically calculate calories and macros
This led to the explosion of macro tracking into the general population. The ease of tracking combined with increasing interest in fitness and online fitness communities created the perfect storm for the trend to grow.
Soon, other apps followed—Lose It, Cronometer, Carb Manager, Macros+, and more—each catering to specific goals like keto, veganism, bodybuilding, or diabetes management.
In the early 2010s, the “If It Fits Your Macros” (IIFYM) movement took off online. The idea was simple: instead of labeling foods as “good” or “bad,” you could eat whatever you wanted—as long as it fit your daily macro goals. This mindset was liberating for some, but controversial for others, as it often led to flexible dieting that ignored food quality in favor of quantity.
🔥 Why It’s Still Big Today
Macro tracking remains popular for several reasons:
Increased body composition awareness: More people are training for aesthetics or strength and want personalized nutrition
Rise of wearable tech: Devices like Apple Watch and WHOOP made performance metrics mainstream, encouraging people to optimize their fuel intake
Accessible data: Apps make tracking easier and more accurate than ever before
Shift from calorie counting to nutrient optimization: Instead of just eating less, people want to eat smarter—more protein, fewer processed carbs, better fats
Additionally, macro tracking has evolved into more than just a diet strategy. It’s now used as a tool for education, habit building, accountability, and athletic periodization. Dietitians, coaches, and personal trainers use it to help clients understand how food fuels different training demands and recovery.
🧾 What People Used to Do Before Apps
Before apps, tracking macros was mostly reserved for high-level athletes and nutrition pros. People used:
Food composition tables in books
Spreadsheets or pen-and-paper food logs
Measuring cups and food scales, often relying on guesswork or "eyeballing" portions
Printed meal plans with fixed portion sizes for each macro group
While effective for some, this system was rigid, error-prone, and not scalable to the general population. The digital age has democratized access to this knowledge—anyone with a phone can now track macros with near-instant feedback.
🔬 Why People Track Macros: The Science
1. For Aesthetic Goals (Fat Loss, Muscle Gain)
Tracking macros helps ensure you're eating the right combination of nutrients to support body composition changes. For example:
Higher protein intake (1.6–2.2 g/kg of bodyweight) has been shown to preserve lean mass during a calorie deficit【Morton et al., 2018】.
Tracking can ensure you’re not unintentionally overeating "healthy" foods and stalling fat loss or muscle gain.
2. For Health Goals (Energy, Blood Sugar, Longevity)
Managing macros can help regulate blood sugar (especially balancing carbs with protein and fat).
Adequate fat intake supports hormone balance—especially in women, where undereating fats can affect menstrual cycles.
Carbohydrates fuel brain and nervous system function—restricting them too much can impair mood and cognitive performance【Benton et al., 2003】.
3. For Awareness
Tracking macros—even temporarily—can teach you about portion sizes, the nutrient breakdown of foods, and how certain meals make you feel. Research shows that self-monitoring food intake increases success in behavior change and weight management【Burke et al., 2011】.
⚖️ The Downsides of Macro Tracking
Tracking isn’t for everyone, and it can come with drawbacks:
Obsessive tendencies: Some people develop anxiety around food if they can’t hit their numbers perfectly.
Loss of intuitive eating: Tracking can cause people to ignore hunger cues.
Inaccuracy: Food databases aren’t always reliable, and measuring everything can be impractical long-term.
Disordered eating risk: For those with a history of disordered eating, tracking can be a trigger.
✅ Who Should Track Their Macros?
Athletes with specific performance or physique goals
Individuals trying to break through fat loss or muscle gain plateaus
People who want to learn more about their nutrition habits
Those with specific nutrient targets (e.g., protein goals for strength training)
❌ Who Shouldn't Track Their Macros?
Anyone with a history of disordered eating
People who find food logging stressful or triggering
Individuals who eat culturally diverse or shared meals that are hard to track
Kids, teens, and older adults who don’t need rigid nutrition control
🧮 How to Calculate Your Own Macros
Macro tracking starts with understanding how much energy your body needs each day—this is called your Total Daily Energy Expenditure (TDEE). Your TDEE is the number of calories you burn in a day through:
Basal metabolic rate (BMR) – what your body needs at rest to function (organs, breathing, etc.)
Physical activity – walking, training, cleaning, etc.
Thermic effect of food (TEF) – calories burned digesting and processing food
🧠 You can estimate your TDEE using online calculators like TDEEcalculator.net. These tools consider your age, weight, height, sex, and activity level.
🔁 Step 1: Choose Your Goal
Once you know your TDEE (i.e., your estimated maintenance calories), decide what you're working toward:
🔹 Maintenance – Eat at your TDEE to maintain your current weight and body composition.
🔹 Fat Loss – Subtract 10–20% from your TDEE to create a calorie deficit. The larger the deficit, the faster the weight loss—but also potentially more muscle loss or fatigue.
🔹 Muscle Gain – Add 5–15% to your TDEE to create a calorie surplus, which helps support recovery and muscle growth.
💡 Example: If your TDEE is 2,000 kcal/day and your goal is fat loss, a 15% deficit would be 2,000 - 300 = 1,700 kcal/day.
🧱 Step 2: Set Your Protein Intake
Protein is the foundation of your macro split. It helps preserve or build muscle mass, supports recovery, and keeps you full.
General guideline: 1.6–2.2 grams per kilogram of body weight
(or 0.7–1 gram per pound)
👉 Choose the higher end (e.g. 2.0–2.2 g/kg) if:
You're in a calorie deficit
You’re training hard or lifting weights
You're aiming to build or retain lean muscle mass
📍 Example for a 70 kg person:
Protein = 2 g/kg × 70 kg = 140g protein
140g protein × 4 kcal = 560 kcal
🥑 Step 3: Set Your Fat Intake
Fat is essential for hormone production, brain function, and nutrient absorption. Too little can negatively impact your energy, mood, and metabolism.
General guideline: 0.8–1.0 grams per kilogram of body weight
(or 20–30% of total calories)
👉 Opt for the lower end if you're in a calorie deficit, and the higher end if you're focusing on maintenance or bulking.
📍 Example for a 70 kg person:
Fat = 1 g/kg × 70 kg = 70g fat
70g fat × 9 kcal = 630 kcal
🍞 Step 4: Fill in the Rest with Carbohydrates
Carbs are your body’s preferred energy source. Once you’ve assigned calories to protein and fat, the remaining calories in your daily total will go toward carbs.
📍 Example so far (2,000 kcal total):
Protein: 140g × 4 = 560 kcal
Fat: 70g × 9 = 630 kcal
560 + 630 = 1,190 kcal used
➡️ Remaining for carbs: 2,000 - 1,190 = 810 kcal
810 kcal ÷ 4 kcal/g = 202g carbs
✅ Final Macro Breakdown (70 kg person, maintenance, 2,000 kcal):
MacroGramsCaloriesProtein140g560 kcalFat70g630 kcalCarbs202g810 kcal
📌 A Few Tips:
This is just a starting point. Your needs may shift depending on training intensity, hormonal cycles, age, and recovery needs.
You don’t have to hit your macros perfectly every day. A weekly average works well for most people.
Use apps like MyFitnessPal, Chronometer, or MacrosFirst to simplify logging.
👀 Do You Have to Track to Be Healthy?
Nope. Some of the healthiest populations in the world (like the Blue Zones) don’t track anything—they simply eat mostly whole, minimally processed foods and move their bodies daily.
Tracking is a tool, not a rule. You can build a healthy, strong, lean body without ever logging a gram. But for the right person, at the right time, it can be incredibly useful.
Macro tracking isn’t about perfection—it’s about awareness. Whether your goals are aesthetic, health-driven, or performance-based, understanding how macronutrients work can help you make more informed decisions. But it’s not the only way to succeed. The best diet is the one you can stick to and feel good living with.
Hope that helps,
Happy Exercising!
📚 References
Morton, R. W., Murphy, K. T., McKellar, S. R., Schoenfeld, B. J., Henselmans, M., Helms, E., ... & Phillips, S. M. (2018).
A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training–induced gains in muscle mass and strength in healthy adults.
British Journal of Sports Medicine, 52(6), 376–384. https://doi.org/10.1136/bjsports-2017-097608Benton, D., & Donohoe, R. T. (2003).
The effects of nutrients on mood.
Public Health Nutrition, 6(6), 673–686. https://doi.org/10.1079/PHN2003490Burke, L. E., Wang, J., & Sevick, M. A. (2011).
Self-monitoring in weight loss: A systematic review of the literature.
Journal of the American Dietetic Association, 111(1), 92–102. https://doi.org/10.1016/j.jada.2010.10.008Thomas, D. T., Erdman, K. A., & Burke, L. M. (2016).
Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and athletic performance.
Journal of the Academy of Nutrition and Dietetics, 116(3), 501–528. https://doi.org/10.1016/j.jand.2015.12.006Wu, Y., Zhang, D., Pang, Z., Li, S., & Li, J. (2021).
Effects of low-fat diets on testosterone levels in men: A meta-analysis of intervention studies.
The Journal of Steroid Biochemistry and Molecular Biology, 210, 105878. https://doi.org/10.1016/j.jsbmb.2021.105878Volek, J. S., Gómez, A. L., Love, D. M., Avery, N. G., Sharman, M. J., & Kraemer, W. J. (2001).
Alterations in steroid hormone concentrations and lipid profiles in men consuming a high-fat, low-carbohydrate diet.
Nutrition & Metabolism, 128(7), 1311–1316. https://doi.org/10.1093/jn/131.11.2819