Protein:
What the evidence
actually says

This is the range supported across the major meta-analyses for people who resistance train. The lower end (1.6g/kg) represents the approximate ceiling for muscle protein synthesis in most adults training consistently. The upper end (2.2g/kg) is used during calorie deficit or by individuals with higher training volumes. The RDA of 0.8g/kg is insufficient for training adaptations and is particularly problematic for older adults, where higher intakes are needed to counteract blunted anabolic signalling. For an 80kg individual, the target range is 128–176g of protein daily.

Anabolic resistance is a well-documented phenomenon in older adults: the muscle protein synthesis response to a given dose of protein is blunted compared to younger individuals. The practical consequence is that older adults need higher protein doses per meal and higher total daily intakes to achieve the same stimulus for muscle maintenance. The Morton et al. 2018 meta-analysis found that the benefit of protein supplementation on fat-free mass gains was reduced with increasing age, but this does not mean protein is less important, it means more is required to achieve equivalent outcomes. Combined with evidence that muscle mass loss accelerates from the fifth decade onwards, this makes adequate protein intake one of the highest-value dietary interventions available.

Muscle protein synthesis is a transient response: it peaks after a protein-containing meal and then returns to baseline over roughly 3–4 hours, regardless of additional protein consumed. Eating all your daily protein in one or two meals is significantly less effective than distributing it across three to four meals. The research on protein distribution (Areta et al., 2013; Moore et al.) consistently supports roughly equal distribution of intake across meals, with each meal providing enough leucine (the key anabolic amino acid trigger) to maximise the synthesis response. This is roughly 0.4g/kg per meal for younger adults, and 0.4–0.6g/kg per meal for older adults due to anabolic resistance.

The concept of the anabolic window, a short period after training during which protein must be consumed or gains are lost, is overstated in most practical contexts. When total daily protein is adequate and distributed properly across meals, the urgency of immediate post-workout protein consumption is greatly reduced. The exception is fasted training: if you trained in a fasted state (typically early morning), consuming protein within 1–2 hours of finishing is more important because you have not eaten for an extended period. If you trained 3–4 hours after a meal, the urgency is low. Total daily intake remains the primary variable.

Not all protein sources are equal, but the gap is smaller than often claimed. The key variables are leucine content (the amino acid that most directly triggers muscle protein synthesis) and digestibility. Animal proteins (meat, fish, eggs, dairy) are generally complete, high in leucine, and highly digestible. Plant proteins vary: soy is the most complete plant protein, while rice, pea, and hemp proteins are lower in certain amino acids. Plant-based individuals can meet requirements by combining sources and targeting the upper end of the intake range. Whey protein is the most studied supplement, performs well due to high leucine content and rapid digestion, and is a practical tool when whole-food intake is insufficient.

When total calorie intake is below maintenance, the body's demand for protein increases for two reasons: more protein is used for energy, and the anabolic stimulus required to spare muscle tissue is higher. The well-established recommendation during calorie restriction combined with resistance training is to increase protein intake to 2.0–2.4g/kg to preserve lean mass. Failure to do so during a cut results in disproportionate muscle loss rather than fat loss. This is one of the most consequential and most commonly ignored points in nutrition practice: most people reduce calories without increasing the protein fraction, and the body composition outcome reflects it.

Beyond its structural role, protein has the highest thermic effect of any macronutrient (roughly 20–30% of its calories are used in digestion and metabolism vs. 5–10% for carbohydrate and 0–3% for fat) and produces the strongest satiety response. Higher protein intakes reduce hunger, improve adherence to calorie targets, and reduce overall food intake across the day without conscious restriction. This makes increasing protein the most practical dietary intervention for anyone trying to manage body composition, because it achieves multiple goals simultaneously: preserving muscle, supporting recovery, reducing appetite, and increasing metabolic cost of digestion.

The concern that high protein intakes damage kidneys or cause other harm persists in popular culture but is not supported by the evidence in healthy adults with normal kidney function. Multiple reviews confirm that intakes up to and exceeding 2.5g/kg/day produce no adverse effects in healthy individuals. The kidney damage concern originates from observations in people with pre-existing chronic kidney disease, where dietary protein restriction is genuinely indicated. This does not generalise to healthy adults. Adequate hydration is advisable with higher protein intakes, but this is good practice regardless.