How to Set Your Macros: A Practical Guide

Calories decide whether you gain, lose, or maintain weight. Macros — protein, carbohydrates, and fat — decide what that weight is made of, how you perform, and how hungry or satisfied you feel getting there. Once you know your daily calorie target, splitting it into macros is what turns a number into an actual eating plan.

What each macro actually does

Protein is the building block for muscle, and it's also the most satiating macro — meaning it keeps you fuller for longer per calorie than carbs or fat. It matters most when you're in a calorie deficit, since adequate protein is what signals your body to hold onto muscle instead of burning it for fuel alongside fat.

Carbohydrates are your body's preferred and most readily available fuel source, particularly for higher-intensity exercise. They're not "bad" or optional for most people — restricting them too aggressively is one of the main reasons low-carb diets feel hard to sustain during training.

Fat is essential for hormone production, including testosterone and estrogen, and for absorbing certain vitamins. Going too low on fat for extended periods can affect hormonal health, which is why every reasonable macro split keeps a meaningful floor of fat intake regardless of goal.

Grams vs. calories

Protein and carbs both provide 4 calories per gram, while fat provides 9 calories per gram — more than double. This is why a "40% fat" split looks smaller in grams than a "40% carb" split at the same calorie percentage: fat packs more energy into less food weight. FitCalc's macro calculator does this conversion for you, turning your percentage split into actual grams to hit.

Choosing a split

• Balanced (40/30/30) — a solid default for general fitness and maintenance, without leaning hard in any direction.
• High-protein (40/40/20) — useful when you're in a calorie deficit and want to protect muscle mass, or when you're training for strength and want to maximise recovery.
• Low-carb (35/15/50) — suits people who feel better, more stable, or less hungry on fewer carbohydrates, though it's a preference rather than a requirement for fat loss.

None of these is objectively "correct." The best split is the one whose food you'll actually eat consistently for months, not the one that looks most optimal on paper for two weeks.

You don't need to hit these exactly

Precision matters far less than consistency. Landing within roughly 10–15 grams of each target on most days will get you the same practical results as hitting the numbers exactly every single day. Treat your macro targets as a compass, not a courtroom.

This guide is for general education and planning, not medical or dietetic advice. If you have a medical condition affected by diet, consult a registered dietitian or doctor before making significant changes.