How much protein do I need each day?

"How much protein do I need?" has two answers: the RDA floor of 0.8 g/kg, which exists to prevent deficiency, and the 1.2–2.0 g/kg range that people who train, diet, or are past 60 actually do better on. At 160 pounds, that's 58 g versus 90–145 g.

Where the 0.8 g/kg RDA comes from

The Recommended Dietary Allowance for protein is 0.8 grams per kilogram of body weight per day for every adult 19 and older — about 0.36 g per pound. It comes out of nitrogen balance research: the average adult breaks even near 0.66 g/kg, and a safety margin was added on top so the published figure covers the large majority of healthy people.

That derivation is the whole story. The RDA answers "what's the least I can eat without slowly losing tissue," not "what intake supports muscle, strength, fullness, or aging well." It's a floor with a guardrail, and it gets quoted as though it settled how much protein per day a person should eat.

The label numbers come from the same place: the Dietary Reference Intakes list 56 g/day for a reference man and 46 g/day for a reference woman, and the Daily Value on the Nutrition Facts panel is 50 g against a 2,000-calorie diet. None of them are personalized. The Acceptable Macronutrient Distribution Range leaves far more room than most people assume — 10% to 35% of total calories.

How much protein do I need if I train or diet?

Once you're asking something of your body, the useful range moves up. Sports-nutrition guidance for active adults generally lands between 1.2 and 2.0 g/kg per day, and where you sit inside that band depends on the job.

Building muscle. About 1.6 g/kg per day captures most of the benefit for people doing resistance training. Recommendations of 1.4–2.0 g/kg are standard; going higher rarely hurts, but the returns flatten.

Endurance training. 1.2–1.6 g/kg. Endurance work does raise protein needs, just less than lifters assume — some amino acid oxidation happens during prolonged sessions, and repair demand climbs.

Losing fat. This is where daily protein intake earns its keep. In a calorie deficit protein does two jobs: it protects lean mass that would otherwise be burned alongside fat, and it's the most satiating of the three macronutrients. Deficit recommendations run 1.8–2.2 g/kg, and the leaner you already are — or the steeper the cut — the higher you push.

Not training at all. Sedentary adults still do better nearer 1.0–1.2 g/kg than at the RDA, mostly for muscle maintenance and appetite control.

One correction matters more than any of the above: if you carry a lot of body fat, scaling grams off total body weight overshoots badly, because fat tissue doesn't need feeding. Use a goal weight instead and the target lands much closer to reality.

How many grams of protein per day, by body weight and goal

Pick your row, then your column. All figures are grams of protein per day.

Body weight	RDA minimum (0.8 g/kg)	Maintain / general activity (1.2–1.6)	Build muscle (1.6–2.0)	Lose fat, keep muscle (1.8–2.2)
120 lb / 55 kg	44 g	65–90 g	90–110 g	100–120 g
140 lb / 64 kg	51 g	75–100 g	100–130 g	115–140 g
160 lb / 73 kg	58 g	90–115 g	115–145 g	130–160 g
180 lb / 82 kg	66 g	100–130 g	130–165 g	150–180 g
200 lb / 91 kg	73 g	110–145 g	145–180 g	165–200 g
220 lb / 100 kg	80 g	120–160 g	160–200 g	180–220 g

Two things worth noticing. The build and lose columns overlap, and that's not a rounding artifact — a deficit raises the requirement enough that cutting often calls for more protein than gaining does. And the distance between the first column and the rest is wide: a 180-pound lifter aiming at 150 g is eating more than twice the RDA, which is normal.

A target only works if you know where you stand at 4 p.m. rather than at bedtime. Protein Tracker is a protein tracking app for iPhone that holds the number you picked from the table and shows the grams left for the day, so it stops living in your head.

Protein requirements by age

Per kilogram, children need more than adults, the number drifts down through adolescence, and then it climbs again late in life.

• 1–3 years: about 13 g/day (1.05 g/kg)
• 4–8 years: about 19 g/day (0.95 g/kg)
• 9–13 years: about 34 g/day (0.95 g/kg)
• 14–18 years: about 52 g/day for boys and 46 g/day for girls (0.85 g/kg)
• 19–50 years: 0.8 g/kg
• 65 and older: 1.0–1.2 g/kg is the widely used geriatric-nutrition figure, rising to roughly 1.2–1.5 g/kg for older adults who are ill, recovering from surgery, or losing weight

The increase after 65 is the part most people miss. Aging muscle responds less strongly to a given dose of protein — anabolic resistance — so both the daily total and the per-meal amount have to be larger to produce the same effect. A 25-year-old gets a near-maximal muscle-building response from roughly 20–25 g in a sitting; older adults generally need a bigger dose, closer to 0.4 g/kg per meal. Spreading intake across the day matters more at 70 than at 25.

One exception overrides the chart: people with chronic kidney disease are often advised to restrict protein, and those targets come from a clinician.

Pregnancy, breastfeeding, and illness

Pregnancy raises the recommended protein intake to 1.1 g/kg per day, stated in the DRIs as 71 g/day for the second and third trimesters, with the same figure applied during breastfeeding. Some researchers argue the real requirement in late pregnancy runs higher than that; prenatal guidance varies enough that this is a question for an OB rather than a number to self-prescribe.

Acute illness, surgery, burns, and enforced bed rest all push needs up, sometimes past 1.5 g/kg, because the body is losing tissue faster than usual. Clinical protocols reflect that. The RDA is not the operative number in those settings.

Where the upper limit actually sits

There is no official one. The DRI committee declined to set a Tolerable Upper Intake Level for protein on the grounds that the evidence was insufficient — which means "not established," not "no ceiling anywhere." The practical bound is the AMDR: stay under 35% of calories and there's still room for the carbohydrate and fat you need.

The kidney worry is misplaced for most people. High intakes do raise filtration workload, but in adults with normal kidney function there's no solid evidence that 2 g/kg or more causes damage. Restriction is standard care for people who already have kidney disease — a different situation, not the same one at a different dose.

The real cost of going very high is elsewhere. Past roughly 2.5 g/kg you start crowding out the carbohydrate that fuels hard training, and the grocery bill climbs for no measurable return. There's little reason to exceed about 2.2 g/kg unless you're deep into a cut at low body fat.

What happens if you consistently undershoot

Chronic underconsumption in someone eating enough total calories rarely looks dramatic. It looks like stalled strength progress, soreness that lingers, and lean mass eroding quietly — fastest during dieting, illness, and after 60, which is exactly when the requirement is highest and appetite is often lowest. You also feel hungrier than your calorie intake predicts, since protein does more per calorie for fullness than carbohydrate or fat.

The textbook signs of true protein deficiency — thinning hair, brittle nails, swelling — belong to severe, prolonged shortfall and are rare where food is plentiful. The realistic risk isn't deficiency. It's spending years a hundred grams short of the intake that would have supported the training you were doing anyway.

FAQ

Is 100 grams of protein a day enough?

For most people under about 160 pounds who train, yes — 100 g works out to roughly 1.4 g/kg at 155 pounds. For a 200-pound lifter, or anyone in a serious calorie deficit, it's on the low side, and 145–200 g fits better. Match the number to your body weight rather than to a round figure.

Does the "1 gram per pound" rule hold up?

It works out to about 2.2 g/kg, which sits at the top of the useful range rather than in the middle. It isn't harmful for healthy adults and the arithmetic is easy, but most people get the same results at 0.7–0.8 g per pound. If your body weight includes a lot of excess fat, the rule overshoots badly.

How many grams of protein a day can the body actually use?

There's no daily cap you can exceed by eating normal food, and the old "30 grams per meal" limit doesn't hold either. Larger single servings are digested and absorbed; the muscle-building response simply plateaus, so a big dose is used less efficiently than the same protein spread out. Three to five meals of 25–45 g is a practical way to reach a high total.

Do vegans need more protein?

Somewhat. Plant proteins are generally less digestible and lower in leucine than animal sources, so adding roughly 10–20% to the target and combining sources across the day — legumes, soy, grains, seeds — closes the gap. Soy and pea protein come closest to animal protein in amino acid profile.