Proteins are large biomolecules consisting of one or more long chains of amino acid residues.

They perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells and organisms, and transporting molecules from one location to another.

Our bodies are constantly recycling proteins, so the ones that we eat in our diet can be used to replace broken down proteins in order to maintain balance.

Protein and Muscle Mass

Muscle mass is built when the net protein balance is positive (+) : muscle protein synthesis exceeds muscle protein breakdown.

Research shows that muscle protein turnover is the greatest after working out and muscle mass increases over time when resistance exercise (i.e. weight lifting, body weight exercises, etc) is combined with nutrient intake.

In general, it is recommended that 10-35% of your daily energy intake comes from protein.

The recommended daily intakes (RDIs) can also be calculated by a person’s body weight. The Academy of Nutrition and Dietetics recommends that the average individual should consume 0.8 grams of protein per kilogram (or 0.35 grams per pound) of body weight per day for general health.

So, a person that weighs 75 kg (165 pounds) should consume an average of 60 grams of protein per day.

But for people who regularly participate in demanding physical activities like Calisthenics, it is recommended that they eat a range of 1.2-1.7 grams of protein per kilogram (or 0.5-0.8 grams per pound) of body weight per day.

Consequently, the same 75 kg (165 pounds) individual should increase their protein intake to around 110 grams in order to maintain muscle mass.

In the table bellow, you can see different weight categories and their daily protein intake requirements :

Weight (kg)	Protein Intake (g/day) 0,8 grams/kilogram	Protein Intake (g/day) 1,45 grams/kilogram
60	48	87
65	52	94
70	56	102
75	60	109
80	64	116
85	68	123
90	72	130

The 30g Protein Myth

– At this point, you must been wondering how to spread that recommended protein intake throughout your day?

Although researches suggest that, for optimal results, you should spread your daily protein intake throughout your meals, truth is there is no ”maximum” amount of protein your body can digest in a meal.

The belief that our body can only digest up to 30 grams of protein at a meal, is completely wrong. You don’t digest up to certain amount of protein and then, all of a sudden, stop digesting food.

Your body will digest all of the protein provided in a sitting, although, most of the protein from a hight protein meal won’t go to building muscle. Hence, if this is your main goal, you should spread the protein you eat throughout the day.

– Now, what really happens to the protein if you eat it all in one meal?

There is no long term storage site for amino acids, the building blocks of protein. Your stomach tissue will hold some amino acids temporarily, but these won’t do much to build muscle later on accordion to this research, from N. Deutz and R. Wolfe.

After eating a meal packed with protein, some of that protein will go into building muscle, some into building other structures in the body (proteins, neurotransmitters etc) and the rest of the protein is used for energy or converted to body fat.

The nitrogen (from amino acids) is combined with other compounds to form urea, which is processed by the kidneys and extracted in the urine.

– But then, how much protein should I eat per meal?

That depends on several factors such as:

• Age
• Training status
• Lean body mass
• Health status
• Total daily calorie intake (if you are cutting calories, total protein needs are higher)
• Overall amount of protein consumed per day
• Quality of protein
• Other nutrients consumed at meal time

Protein and Weight Loss

The balance between the amount of calories you are eating (Total Energy Intake) and the number of calories you are burning (Total Energy Expenditure) is a key factor which dictates your ability to lose weight, maintain optimum weight or improve your body composition.

Total Energy Expenditure is the sum of Resting Energy Expenditure, the thermic effect of food and energy expenditure related to activity. With Resting Energy Expenditure being the largest component (65–75%).

Protein has the potential to play a key role in Resting Energy Expenditure.

Research shows that protein is particularly thermogenic. The metabolic energy of protein is 17 kJ/g, but it’s net metabolizable energy is actually 13 kJ/g, making it lower than either carbohydrate or fat.

This means that you consume more energy digesting protein, than when you digest carbohydrate or fat.

Consequently, a moderate increase in dietary protein combined with a physical activity like Calisthenics may improve the regulation of body weight.

Protein in Foods

In general rich sources of protein are meats, fish, legumes, eggs and milk products.

Protein intake from animal sources rather than plant-based sources tend to have better absorption rates. However, even vegetarians can achieve adequate protein intake when a variety of plant sources are included ensuring intake of all essential amino acids.

Bellow, you can see a list of different food types and their protein content per 100g :

	Food type	Protein content (g) per 100g
Meat protein
Meat	Chicken Beef steak Lamb chop  Pork chop	32.0 31.0 29.2 31.6
Fish	Tuna Mackerel Salmon Cod	23.5 20.8 24.2 20.8
Seafood	Prawns  Mussels  Crabsticks	22.6 16.7 10.0
Eggs	Chicken eggs	12.5
Dairy	Milk   Cheddar   Cottage Yogurt  Low fat yogurt	3.3 25.4 12.6 5.7 4.8
Plant protein
Pulses	Red lentils  Chickpeas	7.6 8.4
Beans	Beans  Tofu	6.9 8.1
Grains	Wheat flour Bread  Rice Oatmeal  Pasta	12.6 7.9 2.6 11.2 6.6
Nuts	Almonds  Walnuts  Hazelnuts	21.1 14.7 14.1

Protein Supplements

Research shows that, intense exercise like Calisthenics needs to be combined with hight protein intake in order for maximal strength and lean mass gains to be achieved.

Therefore, many people and in particular athletes, consume protein supplements to meet the additional demands from training.

Protein powders can provide high-quality protein in a concentrated, convenient form.

Although not everyone needs protein powder supplements, they can assist you if you do intense training and cannot meet your protein needs with diet alone.

In particular, people into Intermittent Fasting need protein asap after their workout, let alone the difficulties they face meeting their daily needs.

To Summarise

Protein is an essential macronutrient for your body.

It is more filling than carbs or fats, helping you feel more satiate with less food. Also, due to it’s thermogenic nature, protein significantly boosts your metabolism by increasing the number of calories you burn.

Moreover, being the building blocks of muscles, protein helps on building and maintaining muscle mass.

As far as our health is concerned, protein can reduce the risk for osteoporosis and bone fractures. Researches show that people who eat more protein tend to have better bone health as they age.

In addition, protein has been shown to lower blood pressure and possibly reduce other risk factors for heart disease.

Finally, protein helps the body repair damaged tissues and organs, speeding up recovery after illness or injury.