How much protein do you actually need per day?

It depends on what you are doing, and the honest answer is a range rather than a number.

The baseline requirement used by most health authorities is around 0.8 g per kg of body weight per day. That figure is set to prevent deficiency in a sedentary adult — it is a floor, not an optimum, and it is often misread as a target for everyone.

For people training regularly, the research consensus sits considerably higher, generally 1.4 to 2.0 g per kg per day, and studies looking for additional benefit above roughly 1.6 g/kg mostly fail to find much for muscle growth. So an 80 kg person training seriously would be looking at somewhere around 112–160 g per day.

In a calorie deficit the requirement rises, often to the upper end or slightly beyond, because higher protein intake helps preserve muscle while losing fat and is the most satiating of the three macronutrients.

Older adults also need more than the baseline. Anabolic resistance means ageing muscle responds less strongly to a given dose of protein, so intake around 1.2–1.6 g/kg is commonly recommended to help maintain muscle mass.

Distribution matters less than total, but not zero. Spreading intake across three or four meals of roughly 20–40 g each appears slightly better for muscle protein synthesis than one enormous serving, though total daily intake is the dominant factor by far.

Very high intakes are not harmful in healthy people, contrary to the common claim about kidney damage — that concern applies to people with existing kidney disease, who should follow medical guidance.

Whole foods cover this comfortably for most people; supplements are convenience, not necessity.