Understanding Macros — Protein, Carbs and Fat Explained

Macronutrients — or "macros" — are the three categories of nutrients that provide energy: protein, carbohydrates and fat. Unlike micronutrients (vitamins and minerals), which are needed in small amounts, macros are needed in large quantities and provide the calories that fuel everything your body does.

Protein — The Builder

Protein provides 4 calories per gram. It's the building block of muscle, but also of enzymes, hormones, antibodies and virtually every structural component of the body. Unlike carbohydrates and fat, the body has no meaningful storage mechanism for protein — excess is converted to glucose or fat.

How much? General recommendations range from 0.8g per kg of bodyweight for sedentary adults (the minimum to prevent deficiency) up to 1.6–2.2g per kg for people doing regular resistance training. If you weigh 75kg and lift weights, 120–165g of protein per day is a reasonable target.

Protein is also the most satiating macronutrient — it keeps you feeling full longer than equivalent calories from carbs or fat, which is one reason high-protein diets tend to reduce overall calorie intake.

Carbohydrates — The Fuel

Carbohydrates also provide 4 calories per gram. They're the body's preferred energy source, particularly for the brain and during high-intensity exercise. Carbs are broken down into glucose, which is either used immediately for energy or stored as glycogen in muscles and the liver.

The distinction between complex carbs (wholegrains, vegetables, legumes) and simple carbs (sugar, white bread, processed foods) matters. Complex carbs are digested slowly, providing sustained energy. Simple carbs cause rapid blood sugar spikes followed by crashes.

Carbohydrates are not essential in the way protein and fat are — the body can produce glucose from protein through gluconeogenesis — but they are the most efficient fuel source for most activities.

Fat — The Essential One

Fat provides 9 calories per gram — more than twice that of protein or carbs. Despite decades of low-fat dietary advice, fat is essential: it's required for absorbing fat-soluble vitamins (A, D, E, K), producing hormones, maintaining cell membrane integrity, and protecting organs.

The type of fat matters. Unsaturated fats (olive oil, avocado, nuts, oily fish) are associated with cardiovascular health. Saturated fats (butter, red meat, coconut oil) should be consumed in moderation. Trans fats (partially hydrogenated oils) are associated with harm and are now banned or restricted in many countries.

Setting Your Macro Targets

Once you know your daily calorie target, a reasonable starting point for most people is: protein 30%, carbohydrates 40%, fat 30%. For someone eating 2,000 calories: 150g protein, 200g carbs, 67g fat.

These ratios shift based on goals — higher protein for muscle building, lower carbs for those following ketogenic approaches, higher carbs for endurance athletes. The macro calculator on this site lets you set your own targets based on your goals.