Calories and Macros Explained: BMR, TDEE and Eating Right

A beginner-friendly guide to daily calories and macros: what BMR and TDEE are, how activity multipliers work, calorie deficit/surplus for weight goals, and balancing protein, carbs and fat.

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Calories and Macros Explained: BMR, TDEE and Eating Right

If you want to reach a nutrition goal, you first need to understand how much energy your body actually requires. This guide explains calories, BMR, TDEE and the three core macronutrients in plain language, with practical examples.

This article is for general information only and is not medical advice. Consult a healthcare professional before making dietary changes.

What Is a Calorie?

A calorie is the unit of energy you take in from food and your body burns. Think of it as a simple balance:

Calories in > calories out → you gain weight (surplus)
Calories in < calories out → you lose weight (deficit)
Calories in = calories out → you maintain weight

Everything revolves around this balance. But you can't set a target without knowing your "calories out." That's where BMR and TDEE come in.

BMR: Basal Metabolic Rate

BMR (Basal Metabolic Rate) is the energy your body burns just to stay alive while resting and doing nothing. Your heartbeat, breathing, cell repair and body-temperature regulation all consume this energy. Surprisingly, BMR is usually 60-70% of your total daily energy expenditure.

BMR is influenced by sex, age, height and weight. The most widely used formula is Mifflin-St Jeor:

Men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
Women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161

If you'd rather not do the math by hand, the BMR Calculator gives you the answer in seconds.

TDEE: Total Daily Energy Expenditure

BMR only covers your resting state. In real life you walk, work and exercise. TDEE (Total Daily Energy Expenditure) is your total daily energy burn, movement included. To find it, we multiply BMR by an activity multiplier:

Sedentary (desk job, little exercise): BMR × 1.2
Lightly active (1-3 days/week): BMR × 1.375
Moderately active (3-5 days/week): BMR × 1.55
Very active (6-7 days/week): BMR × 1.725
Extra active (heavy labor or two daily workouts): BMR × 1.9

A Quick Example

Take a 30-year-old man, 75 kg, 178 cm:

BMR = 10 × 75 + 6.25 × 178 − 5 × 30 + 5 = 750 + 1112.5 − 150 + 5 = 1717 kcal
If moderately active: TDEE = 1717 × 1.55 ≈ 2661 kcal

So this person needs roughly 2,660 calories a day to maintain weight. To track workout burn more precisely, the Calories Burned Calculator is handy.

Deficit or Surplus, Based on Your Goal

Once you know your TDEE, you adjust for your goal:

To lose weight: subtract 10-20% from TDEE. A 300-500 calorie daily deficit means about 0.3-0.5 kg of healthy loss per week.
To gain weight (muscle): add 5-15% to TDEE. A slow, controlled increase minimizes fat gain.
To maintain: stay at TDEE.

A very aggressive deficit (say, 1,000+ calories a day) usually backfires: muscle loss, fatigue and burnout. Slow and steady always wins. To check that your weight goal sits in a healthy range, the BMI Calculator shows your starting point.

The Three Macronutrients

If calories answer "how much," macros answer "from what." There are three macronutrients:

1. Protein (4 kcal/g)

Critical for muscle repair and satiety. It's the most overlooked yet most important macro. Meat, eggs, fish, legumes and dairy are good sources.

2. Carbohydrates (4 kcal/g)

Your body's primary fuel, especially important for training performance. Favor grains, fruits, vegetables and legumes; fibrous, unprocessed sources keep you fuller longer.

3. Fat (9 kcal/g)

Needed for hormone production and vitamin absorption. At 9 calories per gram, it's the most energy-dense source. Olive oil, avocado, nuts and oily fish are healthy choices.

A Flexible Split to Start

As a general starting point:

Protein: 25-35% of total calories
Carbohydrates: 35-50%
Fat: 20-35%

You can shift these ratios based on your goal and preference. To get your own numbers, the Macro Calculator gives the exact calorie and gram breakdown.

Estimating Your Protein Needs

Protein is the most critical macro both for preserving muscle while losing weight and for building it while gaining. A practical range:

Sedentary adult: 0.8 g per kg of body weight
Active / regular exerciser: 1.2-1.6 g per kg
Building muscle or lean cutting: 1.6-2.2 g per kg

Example: for an active 75 kg person, roughly 90-120 g of protein per day is a reasonable target.

Practical Tips

Numbers matter, but execution decides everything:

Consistency > perfection. Hitting 85% of your target for weeks beats hitting 100% for a single day.
Drink water. Under-hydration causes fatigue that's easily mistaken for hunger. The Water Intake Calculator shows your personal need.
Plan protein first, then fit carbs and fat into the remaining calories.
Choose unprocessed foods. For the same calories you eat fuller and more nutritiously.
Measure and review. After 2-3 weeks, adjust calories by 100-200 based on your progress.

In short: learn your BMR, find your TDEE with an activity multiplier, apply a modest deficit or surplus for your goal, and split your macros protein-first. The rest is consistency.