How Much Protein Do You Need a Day?

Protein needs are usually expressed as grams per kilogram of body weight per day, and the range that fits most healthy adults runs from about 0.8 g/kg at the low end to roughly 2.2 g/kg at the high end. Where a person sits inside that range depends on body size, activity, age and goal. The number is not fixed for life; it moves with training load and with what the body is being asked to do.

Protein supplies the amino acids used to build and repair muscle, skin, enzymes and other structures. The body does not store amino acids the way it stores fat, so intake spread across the day matters as much as the daily total. The sections below cover the research, the practical amounts, the per-meal picture, food against powder, and the cautions that apply to kidney disease and certain medications.

What the research shows about daily protein

The reference intake used in many countries is 0.8 g/kg per day for sedentary adults. That figure was set to prevent deficiency in most of the population, not to optimise muscle or support hard training. Reviews of the research consistently find that higher intakes are needed when the goal is muscle gain, preservation during weight loss, or maintenance in older age.

For resistance-trained people trying to add muscle, reviews of controlled trials point to roughly 1.6 g/kg per day as a practical target, with benefits continuing up to about 2.2 g/kg in some studies and little added effect beyond that. For people in a calorie deficit who want to keep muscle, the evidence supports the higher end of the range, around 1.6–2.4 g/kg. For older adults, reviews suggest 1.0–1.2 g/kg as a minimum, and higher when training or recovering from illness.

Evidence strength varies. The case for 1.6 g/kg in trained lifters is strong and comes from many small trials and several reviews. The case for very high intakes above 2.2 g/kg is weaker and mostly applies to lean athletes in aggressive deficits. Claims that high protein harms healthy kidneys are not supported by the research in people with normal kidney function; the caution applies to existing kidney disease, which is covered below.

How many grams per kilogram for each goal

Use body weight in kilograms. To convert pounds to kilograms, divide by 2.2. A 180 lb person weighs about 82 kg.

• Sedentary adult: 0.8–1.0 g/kg per day.
• Recreationally active, general fitness: 1.2–1.6 g/kg per day.
• Muscle gain with resistance training: 1.6–2.2 g/kg per day.
• Fat loss while preserving muscle: 1.6–2.4 g/kg per day, with resistance training.
• Adults over 50: 1.0–1.2 g/kg per day minimum, higher if training.
• Pregnancy and breastfeeding: needs rise, but the amount should be set with a clinician.

These are ranges, not prescriptions. A person carrying more body fat may do better calculating from lean mass rather than total weight, which is one reason a calculator that asks for body composition gives a more useful number. The protein calculator at /tools/protein-calculator/ takes weight, activity and goal and returns a daily target in grams.

A worked example

A 70 kg recreational lifter training three times a week and wanting to add muscle falls in the 1.6–2.2 g/kg band. At 1.8 g/kg that is 126 g per day. Spread over four meals, that is roughly 30–35 g per meal. A breakfast of three eggs and a pot of Greek yogurt, a lunch of chicken and rice, a post-training shake with milk, and a dinner of fish and potatoes would reach that without much effort. Someone with the same weight eating 0.8 g/kg would target 56 g per day, which is closer to two solid meals.

Per-meal amounts and timing

Muscle protein synthesis responds to a single dose of protein, and the response plateaus. Studies using isolated protein sources suggest that roughly 20–40 g of high-quality protein per meal stimulates synthesis well in most adults, with larger doses offering little extra for that meal. Older adults may need the upper end of that range because of anabolic resistance.

Spreading intake across three to five meals is more effective than eating most of it at dinner. The old idea of a narrow anabolic window after training has softened; reviews suggest total daily intake matters more than precise timing, and that protein within a few hours of training is sufficient. A practical approach is to anchor protein to each meal rather than to a clock.

For people who train fasted, a dose of 20–40 g of a complete protein after the session fits the research. For people who eat before training, the post-workout meal can be a normal meal.

Food sources next to powders

Whole foods supply protein alongside micronutrients, and most people can meet their target from food alone. Powders are convenient, not superior.

Powders are useful when appetite is low, when meals are missed, or when a person cannot reach the target from food. They are not required, and a diet built on them alone misses fibre and micronutrients.

BCAA, EAA and glutamine products

The honest case for these is narrower than the marketing suggests.

Branched-chain amino acids (BCAAs) provide leucine, isoleucine and valine. Reviews comparing BCAAs with a complete protein find that BCAAs alone do not support muscle protein synthesis as well, because the other essential amino acids are missing. For someone already eating enough total protein, BCAA supplements add little.

Essential amino acids (EAAs) include all nine that the body cannot make. They can stimulate muscle protein synthesis when taken alone, and small trials support their use when total protein intake is low or when a person cannot eat before or after training. For most people meeting their daily target, EAAs are not necessary.

Glutamine is the most abundant amino acid in the body. It has been studied for gut and immune support in clinical settings, and the evidence there is mixed. For healthy trainees wanting muscle gain, reviews do not support glutamine as an effective standalone supplement.

A complete protein powder, or a meal, covers the same ground more cheaply and with more evidence behind it.

Side effects, interactions and who should avoid high intakes

High protein intakes are generally well tolerated in healthy adults. The most common complaints are digestive: bloating, gas or loose stools, often from a sudden jump in intake or from lactose in some powders. Increasing intake gradually and choosing a powder that suits the gut usually resolves this.

People with chronic kidney disease should not increase protein without medical supervision. The same applies to people with liver disease, and to anyone taking medications that affect kidney function. Protein intake can interact with levodopa, because amino acids compete for the same transporters; timing should be discussed with a prescriber. People with a history of kidney stones may be advised to moderate animal protein and increase fluid intake.

Anyone who is pregnant or breastfeeding, takes prescription medication, or has a medical condition should speak to a doctor or pharmacist before changing protein intake or starting a supplement. Do not stop or change prescribed medication without the prescriber.

Common mistakes and what protein cannot do

• Chasing a single number from a headline. The range matters more than a precise figure, and the right number changes with training and goal.
• Loading all protein into one meal. Distribution across the day is more effective.
• Assuming more is always better. Above roughly 2.2 g/kg, the added benefit for muscle is small, and the extra calories may work against a fat-loss goal.
• Using BCAAs instead of a complete protein. The evidence does not support this for muscle gain.
• Expecting protein to replace training. Protein supports muscle, but resistance training is the stimulus.
• Believing protein damages healthy kidneys. The research does not support this in people with normal kidney function, though it remains a real caution in kidney disease.

Protein cannot spot-reduce fat, cannot replace sleep or training, and cannot compensate for a diet low in overall calories and nutrients. It is one lever among several.

For a personal number, the protein calculator at /tools/protein-calculator/ converts weight, activity and goal into a daily gram target and a per-meal split.