Protein: how much you actually need (and why the answer is not 1 g per kg)

For years the standard recommendation has been: one gram of protein per kilogram of body weight. Simple, memorable, wrong often enough to deserve a serious update. The most recent guidelines (ESPEN 2023, ISSN 2024, EFSA 2023) distinguish at least four different scenarios, and in each scenario the correct answer varies significantly.

Healthy sedentary adult: 0.8–1.0 g/kg is genuinely sufficient to maintain lean mass. Active adult or one in a caloric deficit: 1.2–1.6 g/kg to preserve muscle during weight loss, because in a deficit the body is more inclined to catabolize lean tissue. Strength or endurance athletes: 1.6–2.2 g/kg, peaking at 2.4 g/kg during intense loading. Over 65: the minimum threshold rises to 1.2 g/kg to counter sarcopenia, regardless of activity level, because anabolic efficiency drops with age.

The daily number, however, tells only half the story. Muscle protein synthesis is optimized when intake is distributed across 3–5 meals of 20–40 g protein each. Concentrating everything at dinner, an extremely common Italian habit, reduces the efficacy of even the best daily total: the body is not a warehouse, it is a system that processes repeated stimuli. A 5 g protein breakfast followed by a 60 g dinner is nutritionally less effective than three 25 g meals.

Source quality also matters, judged by amino acid profile and digestibility. Animal sources (eggs, dairy, fish, meat) have complete amino acid profiles and high bioavailability. Plant sources (legumes, grains, nuts) are excellent when smartly combined: legumes plus whole grains in the same meal, or same day, cover all essential amino acids. Nutrilayer models this combination automatically in weekly plans, avoiding the 'tofu at every meal' or 'chicken every day' trap.

A section often overlooked is the role of leucine, the amino acid that acts as the primary signal for triggering protein synthesis. The critical per-meal threshold is around 2.5–3 g of leucine, roughly 25–30 g of animal protein or 35–40 g of well-combined plant protein. Below this threshold the anabolic stimulus is suboptimal, even if the daily total is high. That is why Smart Basket monitors not only total grams but the per-meal structure.

A myth to debunk: 'too much protein damages the kidneys'. In people with normal renal function, intakes up to 2 g/kg/day have not produced any adverse effect documented in the literature. Different is the case of those already diagnosed with kidney disease, for whom their physician's specific indications apply. General rule: when in doubt, talk to a professional, don't apply social-media heuristics.

For retailers this means the protein category is not just meat, and it is far more segmented than shelf layouts today suggest. Flexitarian or vegetarian clusters look for dry and canned legumes, hummus, tempeh, fresh tofu, Greek yogurt, kefir, canned fish, high-protein soy milk. Mapping the nutritional demand of a customer base lets you optimize assortment far more surgically than plain receipt data, capturing a demand that today often leaves traditional stores for specialty shops or vertical e-commerce.

The practical conclusion for the end customer is equally useful. You do not need a per-meal gram-counting app. You need a weekly architecture that ensures at least one quality protein source in every main meal, variety between animal and plant sources, balanced daily distribution, and specific attention during loading periods (sport, work, recovery). Everything else is marginal optimization.