If you've heard fitness influencers talk about "hitting your macros" or seen nutrition labels listing protein, carbs, and fats, you're looking at macronutrients — the three main nutrients your body needs in large amounts for energy, growth, and function.
This guide explains exactly what macronutrients are, how much you need, and how to track them for your specific goals (weight loss, muscle gain, or general health).
Macronutrients (macros) are nutrients your body needs in large quantities to function properly. Unlike micronutrients (vitamins and minerals), which you need in tiny amounts, macros provide calories and are the foundation of your diet. If you're eating plant-based, you'll also want to pay attention to specific micronutrients like iron.
The three macronutrients are:
Notice that fats provide more than double the calories per gram compared to protein and carbs. This is why small portions of nuts, oils, and cheese are surprisingly calorie-dense.
While total calories determine weight loss or gain, your macro split affects:
Two people eating 2,000 calories can have completely different results based on macro distribution. Someone eating 40% protein will retain more muscle than someone eating 10% protein, even at the same calorie intake.
UK government guidelines recommend 0.75g per kg of body weight for sedentary adults. But if you're active, trying to lose weight, or building muscle, you need significantly more.
Optimal protein intake for different goals:
| Goal | Protein per kg body weight | Example (75kg person) |
|---|---|---|
| Sedentary adult | 0.75g | 56g/day |
| Active adult | 1.2-1.6g | 90-120g/day |
| Weight loss | 1.6-2.2g | 120-165g/day |
| Muscle building | 1.6-2.4g | 120-180g/day |
Best protein sources in the UK:
For a complete list of high-protein, low-calorie UK foods, check our guide to high-protein foods available in UK supermarkets.
Simple carbs (sugars) digest quickly and spike blood sugar:
Complex carbs digest slowly and provide sustained energy:
Unlike protein and fats (which have minimum requirements), carbs are flexible. Your ideal intake depends on activity level and goals.
General guidelines:
The NHS recommends that about one-third of your diet comes from starchy carbohydrates, prioritizing wholegrain and high-fiber options.
Healthy fats (prioritize these):
Saturated fats (moderate intake):
Trans fats (avoid):
Minimum: 0.5g per kg body weight (for hormonal health)
Optimal: 0.8-1.2g per kg body weight
Example: A 75kg person needs 60-90g of fat per day (540-810 calories from fat).
Best fat sources in the UK:
Follow these steps to determine your personalized macro targets:
Use our free TDEE calculator to find your maintenance calories, then:
Multiply your body weight (kg) by your activity level:
Example: 75kg active person = 75 × 1.6 = 120g protein/day
Protein calories: 120g × 4 = 480 calories
Multiply your body weight (kg) by 0.8-1.0:
Example: 75kg person = 75 × 0.9 = 68g fat/day
Fat calories: 68g × 9 = 612 calories
Subtract protein and fat calories from your total target, then divide by 4.
Full example for 75kg active person losing weight:
Final macro split: 120g protein, 202g carbs, 68g fat (1,900 total calories)
40% protein, 30% carbs, 30% fat
Why: High protein preserves muscle and increases satiety during calorie deficit.
30% protein, 45% carbs, 25% fat
Why: Carbs fuel intense workouts and support recovery. Protein builds muscle.
20% protein, 55% carbs, 25% fat
Why: Carbs are the primary fuel for long-distance running, cycling, swimming.
30% protein, 10% carbs, 60% fat
Why: Forces body to use fat for fuel instead of carbs (ketosis).
Tracking macros is more precise than just counting calories. Here's how to do it:
Use a nutrition app with UK food databases:
Read UK food labels and log in a spreadsheet or food diary. Look for:
Consistency matters. Weekend overeating wipes out weekday progress.
A tablespoon of oil here, butter there — easily adds 200-300 calories you're not accounting for.
Yes, protein is important, but carbs and fats matter too. Balance all three.
100g raw chicken ≠ 100g cooked chicken. Water loss during cooking concentrates protein. Always weigh raw.
Restaurant meals often have 20-40% more calories than listed due to added oils and sauces.
No. Aim to hit your weekly average. If you're 20g under on protein Monday, make it up Tuesday. Focus on consistency over perfection.
Yes. Meal timing doesn't affect weight loss. Total daily intake matters, not when you eat carbs. Evening carbs may even improve sleep quality.
For healthy people with normal kidney function, high protein (up to 2.5g/kg) is safe. If you have kidney disease, consult your GP before increasing protein.
Advanced strategy: Yes. "Carb cycling" gives you more carbs on training days for energy and recovery, fewer on rest days. Beginners can keep carbs consistent daily.
One day won't matter. But consistently exceeding fat targets means excess calories (since fat is 9 cal/g). Adjust portions the next day to stay on track weekly.
Don't overcomplicate macros. Start with these principles:
Macro tracking is more flexible than restrictive diets. You can eat chocolate, pizza, and dessert — as long as they fit your daily targets. This flexibility makes it sustainable long-term.
Ready to start tracking? Download NutraSafe free and scan your first meal to see your macro breakdown instantly.
← Back to BlogLast updated: February 2026