How much protein do I actually need in a day, and is it that important?

The obsession is mostly justified for people who train — protein is genuinely the most important macronutrient for body composition, and it's the one most beginners under-eat. But the influencer numbers are often inflated. The honest version: The number, from the actual research: ~1.6–2.2g per kg of bodyweight per day if you train and want to build or preserve muscle. So a 70kg person: roughly 110–155g/day. Above ~2.2g/kg, studies show negligible extra benefit for muscle — the '300g of chicken' influencer diets are past the point of return. (Your doctor quoted the ~0.8g/kg RDA, which is the floor to avoid deficiency in sedentary people, not the optimum for someone lifting — you're both right about different questions.) Why it matters so much: 1. Muscle is literally built from protein — insufficient intake means you train hard and can't fully repair/grow. 2. In a fat-loss deficit, adequate protein is what protects muscle so you lose fat instead of muscle (see every 'why don't I look toned' question). 3. It's the most satiating macro — high protein keeps you full, which quietly makes every diet easier to stick to. Practical hitting-the-number: aim for a palm-sized protein source at each meal, and know your cheap staples — eggs, chicken, fish, dairy, and for vegetarians: dal, paneer, soya chunks (very high), Greek yogurt, whey if convenient. Vegetarians CAN hit the target; it just takes more deliberate planning since plant sources are less dense. One myth to drop: 'protein damages kidneys' is false for healthy people — that caution applies to those with pre-existing kidney disease. For a healthy trainee, high protein is safe and, honestly, the single highest-leverage nutrition change most beginners can make.