Proteins are the building blocks of body tissue. They are essential nutrients and can also serve as an alternate source of fuel when needed. Your body uses protein for growth and maintenance. 

Proteins also function as enzymes in membranes and as transport carriers and hormones; their components serve as precursors for nucleic acids, hormones, vitamins, and other integral molecules.

1g of protein contains 4 calories, and you can stock up on proteins from animal sources like meats, dairy products, fish, and eggs and vegan sources like whole grains, pulses, legumes, and nuts. Proteins are made up of amino acids, which are like building blocks.

What Do We Mean By Complete, Incomplete And Complementary Proteins?

Twenty different amino acids join together in various combinations to make all types of proteins. Our bodies can’t make some of these amino acids. Hence, they are essential amino acids because our diet must provide them. 

In terms of diet, protein sources are categorized according to how many of the essential amino acids they provide.

Complete Protein 

They provide all of the essential amino acids. Complete proteins are also referred to as high-quality proteins. Animal-based food sources such as meat, poultry, fish, milk, eggs, and cheese are complete protein sources.

Incomplete Protein

They are low in one or more of the essential amino acids. Plant-based food sources such as grains, lentils, and rice are incomplete proteins.

Complementary Protein

These are two or more incomplete protein sources that together provide adequate amounts of all essential amino acids.  For example, rice contains low amounts of the amino acid lysine and high amounts of the amino acid methionine; however, dry beans contain higher amounts of lysine and lesser amounts of methionine. 

Together, these two food sources can provide adequate amounts of all the essential amino acids required by the human body.

How Much Protein Per Day For Sedentary Individuals

The main factors that determine how much protein an individual needs are training regime and habitual nutrient intake. At the same time, current literature suggests that it may be too simplistic to rely on current recommendations for daily protein intake. 

Various factors need to be considered, such as the quality of proteins according to the biological value of the source, caloric intake, exercise intensity, duration and type of exercise, training history, gender, age, etc.

Currently, the RDA, which stands for Recommended Daily Allowance (average daily level of intake sufficient to meet the nutrient requirements of nearly all (97-98%) healthy people), for protein intake, is 0.8 g/kg of body weight.

But please note, this intake is fine for people who live a sedentary lifestyle and represents an intake level necessary to replace losses and avert deficiency. In simple words, to prevent malnutrition. ¹https://www.nap.edu/read/10490/chapter/12 However, this recommended intake is not enough for active people who indulge in exercise. 

How Much Protein Per Day For Active Individuals

Numerous studies indicate protein requirements for active individuals are approximately double that of the RDA, at least 1.2-2.0 g/kg of body weight. ²https://www.ncbi.nlm.nih.gov/pubmed/26891166, ³https://www.ncbi.nlm.nih.gov/pubmed/20048505 This range is recommended by,

-The Academy of Nutrition and Dietetics 

-The American College of Sports Medicine 

-The International Society of Sports Nutrition also recommends a very similar range of (1.4-2g/kg). ⁴https://www.ncbi.nlm.nih.gov/pubmed/28642676

Here’s an example to illustrate this clearly, suppose an individual weighs about 70 kg (154 lbs), and his energy intake averages around 2,000 calories/day. In that case, his protein requirement depends upon his choice of activity (intensity, duration, and type) and is one of the following:

Individuals engaging in endurance exercise should ingest levels at the lower end of this range, or 1.4 g/kg/day. In this case, the person should consume about 70 (bodyweight in kilos) x 1.4 (g of protein) = 98 g of protein/day.

Individuals engaging in intermittent activities, such as football, rugby, etc., should ingest levels in the middle of this range, or 1.7 g/kg/day. In this case, the person should consume about 70 (bodyweight in kilos) x 1.7 (g of protein) = 119 g of protein/day.

People engaging in strength/power exercises, such as heavyweight training, should ingest levels at the upper end of this range, or 2 grams/kg/day. In this case, the person should consume about 70 (bodyweight in kilos) x 2 (g of protein) = 140 g of protein/day.

How Much Protein Per Day | Maximum Intake

Based on numerous studies and research, one can conclude that for active individuals partaking in physical activities ranging from sports to weight training, the optimal protein range is between 1.2 to 2g/kg. 

So the question that demands attention here is this: Is there any additional benefit of ingesting more than 2g/kg of body weight of protein per day? The additional benefit could be either more muscle gain or superior fat loss.

The top guns performed a systematic review, meta-analysis, and meta-regression in this industry, like Alan Aragon, Menno Henselmans, Brad Schoenfeld et al. ⁵https://www.ncbi.nlm.nih.gov/pubmed/28698222

And they concluded that protein intake at amounts higher than ~1.6g/kg/day does not further contribute to RET (Resistance exercise training)-induced gains in FFM (fat-free mass).

A 2006 study by Hoffman et al. concluded that protein intake above 2g/kg/day did not produce any significant strength or lean mass gains. ⁶https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2129168

So if you are a 70kg individual, you don’t need more than 112g (70*1.6) daily protein for maximal muscle gains. More protein, however, will not result in extra muscle gains! Protein intake above 2 grams/kg/day is only advised in special cases, such as very high energy intake. 

In the above example, if an individual is an athlete and has a caloric requirement of 4,000 calories, then calculating his protein requirement at a modest level of only 12-15 % of the total calories gives us about 150g (15 % of 4,000 calories = 600/4 = 150g), which is 2.14g/kg/day. 

However, these cases are sporadic, and the lower amounts described above should be sufficient for most recreational athletes.

You might wonder if consuming 1.2-2 of protein/ kg of body weight will harm your kidneys. The long-term effects of high protein intake on chronic kidney disease are still poorly understood, and there isn’t significant evidence to link a high protein diet with kidney issues. ⁷https://pubmed.ncbi.nlm.nih.gov/16174292/, ⁸https://pubmed.ncbi.nlm.nih.gov/17369718/

A study compared normal healthy adults following a regular, unrestricted protein diet with a group of vegetarians who maintained a long-term low-protein diet. The results suggest that a high protein non-vegetarian diet does not significantly affect how the kidney functions with regard to ‘normal aging’ in healthy subjects.

However, consult your physician before you embark on a high-protein diet if you have renal issues.