If you only optimise one part of your diet, make it protein. It's the macro that protects muscle when you're cutting, builds it when you're training, and keeps you fullest of the three. But the standard advice — "eat more protein" — is uselessly vague. How much is enough? Does timing matter? Is there a limit? This article gives you the actual numbers, the mechanism behind them, and the practical habits that make hitting your target effortless.

Why protein matters most — the mechanism

Muscle tissue is in constant flux, being broken down and rebuilt every day. Whether you gain, hold, or lose muscle comes down to the balance between muscle protein synthesis (building) and muscle protein breakdown (tearing down). Protein and resistance training are the two levers that tip that balance toward building.

In a calorie deficit, your body is actively looking for tissue to break down for energy. Without enough protein and a training stimulus, some of that energy comes from muscle — exactly what you don't want, because losing muscle lowers your metabolism and leaves you "skinny-fat" rather than lean. Adequate protein, paired with lifting, sends a loud signal to preserve muscle and pull from fat instead.

When you're in a surplus and training, the same mechanism works in your favour: protein supplies the raw material to build new tissue. Either direction you're heading, protein is the lever that decides body composition — not just body weight.

Bodyweight vs lean mass — getting the baseline right

Most guidelines set protein per kilogram of total bodyweight. That's a rough shortcut, and it systematically overshoots for people carrying more fat — fat tissue doesn't need feeding with protein. A more precise method sets protein from lean body mass: the muscle, organs, and bone left after you subtract fat.

To find it: lean mass = bodyweight − (bodyweight × body-fat %). Set protein from that figure and you get a target matched to the tissue that actually uses it. For lean, athletic people the two methods land close together; for someone with higher body fat, the lean-mass method saves them from force-feeding protein they don't need.

The numbers

For most people training and aiming to change their body composition:

  • 2.0 g per kg of lean mass — a solid minimum for general training
  • 2.4 g per kg of lean mass — a strong middle ground for active dieters
  • 2.8 g per kg of lean mass — ideal when dieting hard, to maximise muscle protection in a deep deficit

So an 82 kg person at 20% body fat (about 66 kg lean) would aim for roughly 130–185 g of protein per day depending on the phase. Going meaningfully above this range won't hurt you — protein is safe for healthy kidneys, despite the persistent myth — but it offers diminishing returns and crowds out the carbs that fuel training.

Does timing matter? A little — and not how you think

You may have heard about the "anabolic window" — the idea that you must slam protein within 30 minutes of training or waste the session. In reality the window is hours wide, not minutes. What does help is distribution: spreading protein across 3–4 meals of roughly 30–50 g each maximises muscle protein synthesis better than getting the same total in one giant dinner. So the practical rule isn't "protein immediately after training" — it's "a solid dose of protein at most meals."

Where to get it

Reliable, high-quality sources — lean toward whole foods first, use powder to fill gaps:

  • Chicken, turkey, lean beef, and pork
  • Fish and seafood (bonus omega-3s from oily fish)
  • Eggs and dairy — Greek yoghurt, skyr, cottage cheese are protein-dense and convenient
  • Whey or plant protein powder to top up a meal that falls short
  • Tofu, tempeh, edamame, and legumes for plant-based eaters (combine sources to cover all amino acids)

The habit that makes it automatic

Most people miss their protein target not because it's hard, but because they decide it meal-by-meal and run out of road by dinner. Flip the approach: build every meal around its protein source first, then add carbs and fat. Front-load it — a high-protein breakfast (eggs, skyr, a shake) removes the end-of-day scramble. Hit protein at breakfast and lunch and the daily total largely takes care of itself.

Calculate your exact target

Our free calorie & macro calculator sets your protein from lean body mass automatically — just enter your weight and body-fat percentage and choose how aggressive you want to be. It shows your protein target alongside your full calorie and macro breakdown.

The bigger picture

Protein matters enormously, but it works inside a complete system: the right calories, progressive training, sleep, and consistency over months. Nailing one number won't transform you on its own — but getting protein right makes every other part of the plan work better, which is why it's the first thing we lock in with every client.

If you want a full plan built around your body and your goals, book a free consultation.