Protein Intake Calculator - How Much Protein Per Day (ISSN)

Same weight, three different protein targets

Two people weigh 75 kg. One is cutting fat on a calorie deficit with regular strength training. The other is maintaining weight with recreational exercise. Their protein targets differ by nearly 50%: 165 g/day vs 120 g/day. The difference comes from two variables: your goal (fat loss, maintenance, muscle gain) and your training intensity. This calculator applies ISSN (International Society of Sports Nutrition) guidelines to produce a gram-precise daily target, then breaks it down per meal and lists the most efficient food sources.

Quick example

Male, 80 kg, muscle gain goal, regular strength training (4-5x/week):
Protein per kg: 2.0 g/kg | Daily total: 160 g | Per meal (5 meals): 32 g
That is roughly 500 g of chicken breast or 12 eggs per day - most people need a protein supplement to hit this number consistently.

How to use this calculator - step by step

Body weight - enter your current weight in kilograms. Protein needs scale with body mass. If you are significantly overweight (above 30% body fat), consider using your target weight instead - protein for very obese individuals is better calculated on lean mass, not total weight. Range: 30-200 kg.
Your goal - select one of three options. Fat loss requires the highest protein ratio (1.8-2.4 g/kg) because protein preserves muscle tissue during a calorie deficit and increases satiety. Muscle gain needs elevated protein (1.6-2.2 g/kg) to fuel muscle protein synthesis. Maintenance sits between the two (1.2-2.0 g/kg).
Training activity - choose your exercise frequency and type. Strength training increases protein requirements the most because resistance exercise triggers muscle protein synthesis that demands amino acid availability. Endurance training also increases needs but less dramatically. No training = lowest requirement.
Age (optional) - if you are over 50, the calculator adds 0.2 g/kg to your protein target. This compensates for anabolic resistance - the reduced ability of aging muscle to respond to protein intake and exercise stimulus. Sarcopenia (age-related muscle loss) begins around age 30 but accelerates significantly after 50.
Read your results - daily protein in grams, protein per kilogram, per-meal target (based on 5 meals), a list of high-protein food sources with grams per 100 g, and personalized recommendations for your specific goal and training level.

Practical scenarios

Office worker losing weight
Female, 65 kg, fat loss, no training.
Rate: 1.8 g/kg | Daily: 117 g | Per meal: 23 g.
Strategy: lean protein at every meal, prioritize chicken, fish and cottage cheese.

Recreational gym-goer, maintenance
Male, 80 kg, maintenance, recreational (2-3x/week).
Rate: 1.6 g/kg | Daily: 128 g | Per meal: 26 g.
Easily achievable with whole foods: 200 g chicken + 3 eggs + yogurt + lentil soup.

Competitive lifter, muscle gain
Male, 90 kg, muscle gain, athlete (6-7x/week).
Rate: 2.2 g/kg | Daily: 198 g | Per meal: 40 g.
At this level, whey protein (1-2 shakes) is almost essential to reach the target.

Active senior
Female, 60 kg, maintenance, recreational, age 62.
Rate: 1.8 g/kg (1.6 base + 0.2 age bonus) | Daily: 108 g | Per meal: 22 g.
Age 50+ bump prevents sarcopenia. Strength training 2-3x/week is critical.

Cutting athlete
Male, 85 kg, fat loss, regular strength training (4-5x/week).
Rate: 2.2 g/kg | Daily: 187 g | Per meal: 37 g.
Highest protein priority: muscle preservation during aggressive cut demands maximum intake.

Protein targets by goal and activity (g/kg)

Goal	No training	Recreational	Strength (4-5x)	Athlete (6-7x)
Fat loss	1.8	2.0	2.2	2.4
Maintenance	1.2	1.6	1.8	2.0
Muscle gain	1.6	1.6	2.0	2.2

Values in g per kg body weight per day. Age 50+: add 0.2 g/kg. Based on ISSN position stands (2017, updated 2023).

Top protein sources ranked

Food	Protein per 100 g	Calories per 100 g	Notes
Whey protein isolate	80-90 g	370	Fastest absorption, highest leucine
Chicken breast	31 g	165	Lean, versatile, cost-effective
Beef (lean)	26 g	250	Rich in iron and B12
Salmon	25 g	208	Omega-3 bonus, anti-inflammatory
Cottage cheese	18 g	98	Casein-rich, slow digestion (good before bed)
Eggs (whole)	13 g	155	Complete amino acid profile
Greek yogurt	10 g	59	Probiotics, snack-friendly
Lentils (cooked)	9 g	116	Best plant source, high fiber

Why fat loss demands the most protein

During a calorie deficit, your body breaks down both fat and muscle for energy. High protein intake (1.8-2.4 g/kg) signals to retain muscle tissue while losing fat. A landmark study by Helms et al. (2014) showed that athletes consuming 2.3-3.1 g/kg of lean mass during contest prep retained significantly more muscle than those at lower protein intakes. For non-athletes, 1.8-2.2 g/kg of total weight achieves a similar protective effect without the complexity of calculating lean mass.

Protein also increases satiety more than carbs or fat. The thermic effect of food (TEF) for protein is 20-30% - meaning your body burns 20-30 calories just digesting every 100 calories of protein. For carbs it is 5-10%, for fat only 0-3%. This makes protein a thermodynamic ally during weight loss.

Meal timing and distribution

Current evidence suggests distributing protein across 4-5 meals spaced 3-4 hours apart maximizes muscle protein synthesis (MPS). Each meal should contain at least 20-40 g of protein (the MPS threshold depends on age and meal context). Eating 150 g of protein in two large meals is less effective for muscle maintenance than spreading it across five. A pre-sleep serving of casein-rich protein (cottage cheese, casein shake) provides sustained amino acid release overnight.

FAQ

Is too much protein bad for kidneys?

In healthy individuals, no. A 2016 meta-analysis (Devries et al.) found no evidence that high protein intake (up to 2.5 g/kg) damages kidney function in people without pre-existing kidney disease. The kidneys adapt by increasing glomerular filtration rate. However, people with chronic kidney disease (CKD) should follow their nephrologist's protein guidelines, which are typically lower (0.6-0.8 g/kg).

Can I get enough protein from plants alone?

Yes, but it requires planning. Plant proteins are generally less leucine-dense and less digestible (DIAAS score) than animal proteins. To compensate: eat 10-20% more total protein, combine complementary sources (rice + beans, bread + hummus), and consider soy or pea protein isolate as a supplement. Tofu (8 g/100 g), lentils (9 g/100 g), tempeh (19 g/100 g) and seitan (25 g/100 g) are the densest plant sources.

Do I need protein immediately after a workout?

The "anabolic window" is wider than commonly believed. Research shows that muscle protein synthesis remains elevated for 24-48 hours after resistance training. Having protein within 2-3 hours post-workout is beneficial, but the precise timing matters less than total daily intake. If you trained fasted (morning, no breakfast), eating sooner is more important. If you had a protein-rich meal 2-3 hours before training, the urgency is minimal.

Why does the calculator use body weight instead of lean mass?

For simplicity and accessibility. Lean body mass requires knowing your body fat percentage (measured by DEXA, calipers or the Body Fat Calculator). For most people with body fat between 15-30%, using total weight with the ISSN multipliers produces a result within 5-10% of lean-mass-based calculations. Only for very obese individuals (above 35% body fat) does using total weight significantly overestimate needs.

What is the difference between whey and casein protein?

Whey is a fast-digesting protein that spikes blood amino acids within 30-60 minutes. Best for post-workout or morning meals. Casein is slow-digesting - it forms a gel in the stomach and releases amino acids over 4-7 hours. Best before bed to sustain MPS overnight. Both have excellent amino acid profiles. If you only buy one supplement, whey is more versatile. If you can have two, add casein (or eat cottage cheese) before sleep.

How does age affect protein needs?

After age 50, anabolic resistance increases - muscles respond less efficiently to the same amount of protein. The MPS threshold per meal rises from ~20 g to ~35-40 g. Additionally, sarcopenia causes 1-2% muscle loss per year after 50 if unaddressed. The solution: higher protein intake (+0.2 g/kg, as this calculator applies) combined with resistance training. Studies show that adults over 65 who consume 1.6+ g/kg protein and train with weights maintain muscle mass comparable to younger adults.

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