🧬 What Is Protein and Why Does Your Body Need It?
Protein is one of the three macronutrients — alongside carbohydrates and fat — and is the only macronutrient your body cannot synthesise from scratch. It is made up of amino acids, which serve as the building blocks for muscle tissue, enzymes, hormones, immune cells, and virtually every structural component of your body.
Unlike fat (stored in adipose tissue) or carbohydrates (stored as glycogen), your body has no dedicated protein storage. This means you need a consistent daily supply through food — and the amount you need depends heavily on how much you exercise, your body weight, your age, and your goal.
Resistance training creates micro-tears in muscle fibres. Protein — specifically leucine, the anabolic trigger — initiates muscle protein synthesis (MPS), rebuilding fibres thicker and stronger. Without adequate protein, the training stimulus is wasted.
During a calorie deficit, your body can break down muscle for energy. High protein intake (1.8–2.4 g/kg) signals the body to preserve lean mass — so the weight you lose comes from fat, not muscle. This is the single most important dietary intervention during a cut.
Protein has a thermic effect of 20–30%, meaning your body burns 20–30 kcal just to digest 100 kcal of protein. This gives high-protein diets a built-in metabolic advantage over equivalent-calorie high-fat or high-carb diets.
Protein is the most satiating macronutrient. It suppresses ghrelin (hunger hormone) and elevates PYY (fullness signal) more effectively than carbs or fat. Studies show that increasing protein to 30% of calories reduces overall food intake by ~440 kcal/day on average.
🧮 How the Protein Intake Calculator Works
This calculator uses the g/kg bodyweight method — the standard used in sports nutrition research. Enter your weight, select your activity level and goal, and the calculator applies the evidence-based range published by the International Society of Sports Nutrition (ISSN) and the American College of Sports Medicine (ACSM).
Use your total body weight in kg or lbs. For best accuracy, use your lean body mass (total weight × (1 − body fat fraction)) if you know your body fat percentage — this removes adipose tissue from the calculation, since fat cells have minimal protein needs.
The recommended protein range varies significantly by goal. Sedentary individuals need just 0.8–1.0 g/kg for basic maintenance. Athletes and those cutting body fat need up to 1.8–2.4 g/kg to support performance and muscle retention.
Your result is a daily range (minimum to maximum) based on ISSN guidelines, plus a recommended midpoint. Aim for the midpoint as your daily target and adjust up or down based on progress over 2–4 weeks.
📊 Evidence-Based Protein Recommendations by Goal
Sources: ISSN Position Stand (Stokes et al. 2018), ACSM/AND/DC Joint Statement, Helms et al. 2014 (systematic review), PROT-AGE Study Group. Ranges represent the evidence-based consensus — individual needs may vary.
🧪 Example Protein Calculation
🍖 Best High-Protein Foods (per 100g)
Values are approximate per 100g raw weight unless stated. Cooked weights vary — chicken loses ~25% water weight when cooked, increasing protein concentration to ~38g/100g cooked.
⏰ Protein Timing: Does It Matter?
Research on protein timing has evolved significantly. While the "anabolic window" (eating protein within 30 minutes of training) was once considered critical, the current consensus is more nuanced. Total daily protein intake matters far more than timing for most people.
Overnight fasting naturally lowers muscle protein synthesis. A protein-rich breakfast (30–40g) helps restart MPS and provides leucine to trigger the anabolic response. Eggs, Greek yogurt, or a protein shake are effective choices.
Consuming 20–40g of protein within 2 hours before or after resistance training is associated with improved muscle protein synthesis. The type of protein matters less than the quantity — whey, casein, and soy all work.
Casein protein (found in cottage cheese, Greek yogurt, milk) digests slowly over 6–8 hours, maintaining elevated blood amino acids overnight. A pre-sleep protein serving of 30–40g is associated with improved overnight muscle repair.
Is too much protein dangerous?
For healthy adults with normal kidney function, there is no evidence that high protein intake (up to 3.5 g/kg) causes harm. The 'protein damages kidneys' claim applies only to people with pre-existing kidney disease. Healthy kidneys handle excess protein efficiently. The main practical concern is that very high protein makes it harder to hit carb and fat targets within your calorie budget.
Plant-based protein: what to know
Plant proteins (legumes, soy, grains) are often lower in one or more essential amino acids. Soy and quinoa are complete proteins. Others benefit from combining sources (rice + beans covers all essential amino acids). Leucine content is lower in plants, so vegans may need 10–15% higher total protein or should prioritise soy, edamame, and tempeh.
Protein needs for older adults (60+)
Muscle loss (sarcopenia) accelerates after 60. The PROT-AGE study group recommends 1.2–1.6 g/kg for healthy older adults — significantly above the WHO minimum of 0.8 g/kg. Older muscles also show anabolic resistance, meaning higher protein doses per meal (40g+) are needed to trigger the same MPS response seen in younger adults.
Protein supplements: worth it?
Protein supplements (whey, casein, plant blends) are a convenient way to fill protein gaps — they are not superior to whole food sources per gram of protein. Whey protein is especially high in leucine and fast-digesting, making it useful post-workout. Whole foods provide additional micronutrients, fibre, and satiety that supplements do not.
🧠 Practical Strategy to Hit Your Protein Target
- → Build every meal around a protein source — then add carbs and fat
- → Use a food tracking app (MyFitnessPal, Cronometer) for the first 2–4 weeks
- → Prep protein sources in bulk (batch-cook chicken, hard-boil eggs)
- → Keep high-protein snacks on hand (Greek yogurt, cottage cheese, jerky)
- → Add protein powder to oats, smoothies, or yogurt to close the gap
- → Weigh food raw for accuracy — cooked weights vary by water loss
- → Eating most protein in one meal — spread it across 3–4 meals
- → Relying only on protein shakes and neglecting whole food sources
- → Underestimating protein in cooked food (chicken is ~38g/100g cooked)
- → Assuming plant-based eating automatically meets protein needs
- → Not adjusting protein intake as body weight changes
- → Ignoring protein during a calorie deficit — this is when it matters most
🍽️ Sample High-Protein Day (150g Protein, 2,000 kcal)
Frequently Asked Questions
How much protein do I need per day?
The right amount depends on your weight, activity level, and goal. The general population minimum is 0.8 g/kg (WHO). Active individuals need 1.2–1.6 g/kg. Athletes and those in a fat-loss phase need 1.6–2.4 g/kg. Use the calculator above to get your personalised range — it is more accurate than a flat gram number because it scales to your body weight.
Can I eat too much protein?
For healthy adults with no pre-existing kidney disease, high protein intake (up to 3.5 g/kg) has not been shown to cause harm in research. The concern about kidney damage from protein applies only to individuals with chronic kidney disease. The practical limit is more about hitting your calorie budget — very high protein intake leaves less room for carbs and fats.
Does protein timing matter — should I eat protein after workouts?
Protein timing is less critical than once believed. The "anabolic window" is real but wide — consuming protein within 2 hours before or after training is sufficient. What matters most is total daily protein intake distributed across 3–4 meals. Pre-sleep protein (casein-rich foods like cottage cheese) can additionally support overnight muscle repair.
Is whey protein better than food sources?
Whey protein is a convenient, high-quality source — it is rich in leucine and fast-digesting, making it effective post-workout. However, it is not superior to whole food sources per gram of protein. Whole foods like chicken, eggs, and Greek yogurt provide additional micronutrients, water content, and greater satiety. Supplements should complement, not replace, whole foods.
How do vegans and vegetarians meet protein needs?
Plant-based eaters can absolutely meet their protein needs with planning. The best plant protein sources are soy (tofu, tempeh, edamame), legumes (lentils, chickpeas, black beans), seitan, and quinoa. Because most plant proteins are lower in leucine — the key trigger for muscle protein synthesis — vegans may benefit from eating 10–15% more total protein than the standard recommendation and should prioritise leucine-rich plant sources.
How much protein can I absorb per meal?
There is no strict ceiling on protein absorption — your body will digest and absorb protein from any meal size. However, the amount that maximally stimulates muscle protein synthesis (MPS) per meal is approximately 20–40g for most adults (higher for older adults). Eating more in one sitting doesn't 'waste' protein — excess amino acids are used for other functions or oxidised — but distributing protein across 3–4 meals optimises the MPS signal throughout the day.
Does protein intake need to change as I age?
Yes. From age 60+, muscles become progressively resistant to the anabolic signal from protein (anabolic resistance). The PROT-AGE study group recommends 1.2–1.6 g/kg for healthy older adults — significantly above the WHO minimum. Older adults also benefit from higher protein doses per meal (35–40g) to overcome this resistance, and from combining protein intake with resistance exercise.