Why do we need protein?
There is a common misconception that protein is only used for building muscle but protein is actually one of the essential macronutrients needed by the body to function. Its main role is to build and repair muscle but it also plays a crucial role in almost all biological processes.
Protein is made up of amino acids, some of which the body is able to produce itself and some of which we need to obtain from our diet – these are called essential amino acids. There are nine essential amino acids and they are involved in a number of important and varied processes in the body, including:
- tissue growth and repair
- energy production
- immune and enzyme function
- hormone production
- nutrient absorption.
The best sources of essential amino acids are animal-based proteins like meat, eggs and poultry. When you eat protein, it’s broken down into amino acids, which are then used to help your body with the various processes noted above.
Although amino acids are most recognised for their role in muscle development and repair, the body depends on them for much more. That’s why essential amino acid deficiencies can negatively impact your entire body including your nervous, reproductive, immune and digestive systems.
So, eating protein is clearly essential for the body to function, but how is it beneficial specifically in relation to weight control, muscle gain and health?
1. It has a high satiety effect, so you feel fuller for longer
2. It preserves muscle mass during weight loss
3. It builds lean muscle mass and strength
4. It helps to repair muscle after exercise
5. It has a high thermogenic effect.
1. It has a high satiety effect, so you feel fuller for longer
Protein has been shown in research to be the most satiating of all the macronutrients, meaning it helps you feel fuller for longer.
For this reason, you are less likely to snack or give in to cravings, and more likely to eat fewer calories per day as you are not feeling as hungry. This is particularly beneficial for those looking to lose weight. (1, 2, 3).
2. It preserves muscle mass during weight loss
You don’t just want to lose weight, you want to look ripped … well, you can’t do that without muscle. If you start to lose lean muscle mass, you’ll only end up looking like a skinnier version of your previous self. This might suit some but not most!
It is not impossible, but it can be very difficult to build muscle with a reduced energy intake. Therefore, the next best thing you can do is to keep hold of the lean muscle mass you already have, which means doing two things: lifting weights and eating enough protein.
One study showed that a protein intake of roughly 2.3g/kg compared to 1g/kg made a significant difference to the preservation of muscle whilst dieting, while another showed how a reduced carbohydrate to protein ratio lead to greater improvements in body composition and better ratio of fat/muscle loss (6, 7).
3. It builds lean muscle mass and strength
When you lift weights, you stress and break down your lean muscle mass. Seeing as protein is the building blocks of your muscles, you need to eat adequate protein in order to repair and build them. An insufficient protein intake – also known as a negative nitrogen balance – will mean that your body is breaking down muscle quicker than it can repair and build it.
On the other hand, a sufficient protein intake – also known as a positive nitrogen balance – will not only help repair stressed and broken down muscle but also facilitate new muscle growth and strength (3).
4. It helps to repair muscle after exercise
Although protein is necessary for many vital bodily processes, it is also important for repair and recovery. If you participate in regular exercise (particularly resistance training) your body will break down muscle tissue on a regular basis. Therefore, a sufficient protein intake will ensure that your body is repairing any muscle damage and maximise your performance in your training sessions.
5. It has a high thermogenic effect
It has been shown that protein can increase calorie expenditure (calories out) by 80 to 100 calories per day (4, 5). This is known as the thermogenic effect of protein and is the result of the metabolic cost of breaking down protein into amino acids for use in the body.
This means that 20-30% of the calories in protein are burned off just in its digestion (the numbers are much less for dietary carbohydrates and fats).
In simple terms, if you were to eat 100 calories worth of protein, your body would effectively use some of those calories to breakit down (roughly 20-30%). This would result in a lower net calorie intake, which again would be beneficial weight loss.
It’s worth noting that if you’re looking to gain weight, more protein isn’t necessarily better. Over-fill on protein and you may not be able to stomach the extra calories needed to add muscle.
How much protein do I need?
The amount of protein you need depends on your goals, body composition and dieting considerations.
For the general population, a minimum intake of 0.8g/kg per day represents the minimum amount to avoid conditions associated with a protein deficiency, such as Anaemia or Kwashiorkor.
However, this intake is not optimal for most and higher protein intakes will help maintain healthy hair, skin, and immune function, promote weight loss and retain muscle mass.
So how much protein do I actually need?
- General weight loss / health clients – 0.8g/kg-1.2g/kg per day is recommended.
- Endurance athletes – 1.2g-1.7g/kg per day is recommended.
- Muscle gain clients / body-builders – 1.8-2.7g/kg per day is recommended.
The elderly need higher protein intakes than the younger population in order to reduce the risk of age-related diseases, such as sarcopenia. This is because lean muscle mass becomes less sensitive to stimuli such as protein (amino acids) within the body and resistance training. Therefore, aiming for a slightly higher protein intake (1.2g/kg or more) is recommended.
How can I get enough protein in my diet?
A simple way to ensure you’re getting enough protein is to aim for a serving in each main meal throughout the day, with a high protein snack in-between.
A visual serving of protein would be one palm-sized portion of meat or fish for women, and a 1.5-2 palm-sized portion for men. That’s around 20-30g of protein per portion if you’re a woman, and 30-40g of protein per portion if you’re a man.
What are good sources of protein?
Animal-based sources of protein contain all the essential amino acids in adequate amounts – these are known as ‘complete’ protein sources. However, plant-based sources of protein are deficient in at least 1 of the 9 essential amino acids – and are known as ‘incomplete’ protein sources.
This is why it is important for vegans and vegetarians to combine and eat a wide variety of plant-based protein sources to make sure they are getting all of their essential amino acids through their diet.
Popular protein sources include:
- Beef (extra lean mince, steak, burgers, meatballs)
- Chicken (fillets, sausages, burgers)
- Turkey (fillets, mince, steaks, bacon rashers)
- Fish (tuna, salmon, mackerel, haddock, pollock, sea bream, prawns)
- Dairy (milk, greek yogurt, quark, cottage cheese, kefir)
- Eggs
- Plant-based (tofu, tempeh, beans, lentils, etc)
- Protein powders (whey, soy, pea protein).
Do you need to supplement with protein?
Protein supplementation really depends on how much protein you are getting in your diet already. If you’re getting enough protein from whole foods, you don’t need to take any protein supplements.
If you find it difficult to regularly hit your protein targets with whole foods, supplementing with a protein powder or bar can help. There are lots on the market and choosing the right one for you comes down to personal taste, lifestyle, budget and allergies.
Summary
Protein is a building block for healthy bones, muscles, hair, teeth, cartilage, skin and blood. It is an important macronutrient as it contains essential amino acids that the body needs but cannot produce itself for use in many vital processes.
Protein is particularly important for building and repairing muscle, and preserving muscle mass during weight loss. If you exercise regularly it is important to make sure you get enough protein in your diet, especially if you are weight training and/ or trying to build lean muscle mass and strength.
