- How many grams of protein do I need per day?
- It depends on your weight, training, and goal. A 70 kg sedentary adult who just wants to stay in nitrogen balance needs about 56 g/day (0.8 g/kg, the official DRI). A 70 kg lifter trying to build muscle needs 112–154 g/day (1.6–2.2 g/kg, ISSN 2017 position stand). A 70 kg person on a fat-loss cut who wants to preserve muscle needs 126–168 g/day (1.8–2.4 g/kg, Helms et al. 2014). Use the calculator — type your weight, pick your goal, read the gram target.
- Why does the calculator show a range, not a single number?
- Because the published evidence shows a range, not a single point. The Morton et al. 2018 meta-analysis found resistance-trained adults stop seeing benefit somewhere between 1.62 and 2.20 g/kg — the upper bound is wide because individual response varies (genetics, training experience, total calorie intake). Pretending the answer is one decimal place when the data is a range is false precision. The calculator shows the band and a midpoint; aim for the midpoint, drift toward the high end if you're a heavier-trained lifter or in a cut.
- Why does the recommendation jump from 0.8 to 1.6 g/kg as soon as I pick 'build muscle'?
- The 0.8 g/kg DRI is the minimum to not lose lean mass — it was set for sedentary adults using nitrogen-balance studies. As soon as you add resistance training, the curve changes. Muscle protein synthesis (MPS) is stimulated by both lifting and eating protein; with low protein, lifting can't build muscle even if the calories are there. The ISSN's threshold of 1.6 g/kg is the lower bound that captures most of the gain in trained subjects across the published literature. If you're lifting and eating 0.8 g/kg, you're under-fuelling the response your training is asking for.
- Why is the cut band (1.8–2.4 g/kg) the highest of all the bands?
- Because in a caloric deficit, your body is more willing to break down muscle for amino acids (energy and gluconeogenesis substrate). Protein both stimulates MPS and suppresses muscle protein breakdown; you need more of it in a deficit than in maintenance or surplus. Helms et al. 2014 reviewed the cut literature in lean athletes and landed on 2.3–3.1 g/kg of lean body mass; converted to total body weight that's ~1.8–2.4 g/kg for a typical body-fat range. Higher protein during a cut also improves satiety, which makes the deficit easier to stick to.
- Should I use my current weight or my goal weight?
- Current weight is the default and is what most ISSN/ACSM protocols are calibrated against. If you're carrying significant excess body fat (say, BMI > 30) and you want a tighter estimate, use goal weight or estimated lean body mass — body fat doesn't need protein. For everyone else (lean to moderate body fat), current weight is the right input. If you adjust your weight as you cut or bulk, recalculate every 4–6 weeks.
- Is too much protein bad for my kidneys?
- Not in healthy adults. The often-cited concern came from studies in patients with pre-existing chronic kidney disease, where high protein worsens an already-impaired filtration. In adults with normal kidney function, intakes up to 3 g/kg have been studied in athletes (Antonio et al. 2014, 2016) with no measurable harm. If you have diagnosed kidney disease or are at risk, this calculator's recommendations are not for you — talk to your nephrologist about a specific target.
- Does it matter when I eat the protein?
- Distribution matters more than timing. Spread the daily total across 3-5 meals of ~30-40 g each. The muscle-protein-synthesis response to a single meal saturates around 20-40 g of high-quality protein for most adults (Schoenfeld & Aragon 2018), so eating 100 g at one sitting isn't twice as anabolic as 50 g — the rest is essentially carbs and calories from a synthesis standpoint. The classic 'anabolic window' (eat within 30 minutes of training) is much less important than people thought; what matters is hitting the daily total with reasonable spacing.
- What counts as 'protein'?
- Complete proteins from animal sources (chicken, beef, fish, eggs, dairy) and complete plant sources (soy, quinoa) give you all nine essential amino acids in the ratios MPS needs. Incomplete plant sources (rice, beans, nuts) can be combined to get a complete profile. Look at the 'protein' line on a food label, not 'high-protein' marketing claims. A typical chicken breast (~150 g cooked) has ~46 g protein; a cup of Greek yogurt (~245 g) has ~23 g; an egg has ~6 g; 100 g of tofu has ~17 g.
- Why does sedentary + 'build muscle' or 'lose fat' still recommend the active bands?
- Because the protein recommendations for building muscle or preserving it during a cut are conditional on resistance training. If you're not lifting, protein alone won't build muscle, and the higher band is overkill for fat loss without training (the lower bound is enough to maintain the small amount of muscle you have). The calculator assumes that if you pick 'build muscle' or 'lose fat', you're either training now or starting soon. If you're truly sedentary and just want to maintain, pick 'maintain' — the calculator drops you to 0.8 g/kg.
- Why aren't supplements (whey, casein, BCAAs) special-cased?
- Because they're not — protein is protein. Whey, casein, soy isolate, and plant blends all count toward the daily total on a gram-for-gram basis. Whey is digested fastest, casein slowest; for most people that's a wash because muscle-protein synthesis is driven by daily intake more than per-meal kinetics. BCAAs (leucine, isoleucine, valine) are the three essential amino acids most directly tied to MPS, but eating complete protein already gives you them — supplementing BCAAs on top of adequate protein doesn't add anything. If you hit your daily gram target from whole food, you don't need any supplement.
