Protein is a vital nutrient, responsible for muscle growth and maintenance, optimal body function, satiety and so much more – but not everything you hear about protein is correct.
Protein is essential – without it, your body would simply waste away. However, while too little protein means you can’t grow or sustain your body properly, too much protein may actually increase your risk of certain health problems.
It’s important you learn how to strike a good protein balance.
What is protein?
Or perhaps you should ask, what isn’t protein? Remove the water from your body, and protein accounts for around 75% of what’s left. Your hair, skin, muscle, bone and almost every other body part or tissue is made up of protein; you are protein!
But what does this have to do with protein in your diet? Dietary protein is often described in terms of amino acids, which are the building blocks your body uses to make the proteins which keep you alive. Your body needs 22 different amino acids (called essential amino acids) in order to make all the necessary proteins. 13 of these amino acids are made by your body itself, but the other nine of them must come from food (these are called non-essential amino acids), which is why you need protein in your diet.
The foods you eat for protein can be described in two ways:
Complete proteins – These are foods which contain all nine non-essential amino acids you need to obtain from your diet. All meat and other animal products are sources of complete proteins. These include meat, poultry, fish, shellfish, eggs, milk and milk products.
Incomplete proteins – These are foods which are low in protein, or contain only some of the nine amino acids you need from your diet. Vegetable protein is usually considered incomplete, as it’s missing one or more essential amino acids. However, as long as you eat a variety of foods throughout the day, it’s easy to get all nine amino acids even without eating animal products.
What is protein for?
Protein is food for your body. It’s used to build new tissue, which is why there’s an increased need for protein during periods of growth such as in infancy, childhood, adolescence and pregnancy. Here are some of the other roles protein plays:
- Provides structure for muscles, hair and blood
- Repairs worn-out body tissue proteins resulting from general “wear and tear” to your body
- Supplies emergency energy when you’re not getting enough carbohydrates or fats from your diet
- Helps transport important nutrients such as iron and cholesterol throughout your body
- Supports your immune system
- Builds cardiac (heart) muscle
- Contributes to numerous essential body secretions such as hormones and enzymes. The only protein-free body fluids are urine and bile.
Protein and muscle. People are often misled about the role of protein in building muscles. Although muscles are made of protein, carbohydrate is actually the best form of “fuel” for muscles which are exercised for long periods of time. In fact, a diet high in protein and fat, but low in carbohydrates, can significantly reduce the performance of endurance athletes. Excess protein in foods won’t build bigger muscles. It’s simply converted to, and stored as, fat.
How much protein do you need?
On average, Australians eat far too much protein. The current recommendation is that proteins make up around 15-20% of your total calories for the day. Protein contains four calories per gram, so for a 2000 calories-per-day diet, you could eat 75-100 grams of protein. However, most people consume more than that. Eating too much protein can actually be damaging to your body.
A more accurate way of calculating your protein needs is to allow 0.8g of protein per kg of body weight each day. For example, a 60kg person would require 48g of protein per day. Growing children need about 1g of protein for every 1kg of body weight. For example, a 25kg child needs about 25g of protein a day to sustain their growth.
The table below lists the recommended minimum protein intake for different people.
Recommended Daily Protein Intake (grams)
|Minimum Protein Requirements|
Source: Allan Borushek’s Pocket Calorie, Fat and Carbohydrate Counter 2007.
High-protein diets – are they safe?
Weight loss in the first few months of a high-protein diet is sometimes faster than with a calorie-controlled diet, primarily because of the resulting water loss. However, studies have shown after a year, weight-loss results are the same on a calorie-controlled diet.
But is a high-protein diet safe? Evidence suggests the answer is no – especially if it’s followed for more than a few weeks. Studies show the average Australian already eats double the amount of protein than recommended. People on high-protein diets put away even more protein, consuming up to 34% of their total calories from protein and up to 53% from fat, much of which is saturated fats (the “bad” fat) from meat and dairy products.
The extra fat alone is enough to increase your risk of coronary heart disease, stroke and other illnesses. But excess protein has also been proven to have negative consequences for health and well being, including:
- When there is too much protein and not enough carbohydrates in the diet, your body is forced to burn fat because it’s deprived of essential carbohydrate energy. This process is called ketosis. The energy from fat is “last resort” energy and doesn’t provide your body or mind with the fuel they need, which is why people on high-protein diets feel easily tired and can suffer from exhaustion.
- Ketosis also produces ketone bodies. When too much protein is consumed these ketones build up in your body, causing damage to your liver and kidneys.
- When protein is broken down and metabolised, it also raises the levels of uric acid in the blood. The more protein you consume, the more of this toxic by-product the body has to deal with. The body pumps a lot of water through the kidneys and urinary tract to try and flush it out. This water loss not only gives a false indication of weight loss, it’s also detrimental to your body in many other ways.
- Digesting too much protein releases acids that your body usually neutralises with calcium. As calcium reserves are used for this process instead of building bones, your risk of bone deficiency and osteoporosis increases.
- Other common discomforts of a high-protein diet can include bad breath, bad body odour, constipation, dehydration, dizziness, headache, mental fatigue, sleep problems and nausea.
Can vegetarians get enough protein?
It was once believed vegetarians had to carefully combine plant protein sources within each meal to obtain all nine essential amino acids. However, studies have shown the human body can store essential amino acids and combine them as necessary. So, while combining beans and rice, or peanut butter and bread produces a “complete” protein, in most cases it’s not necessary to consciously do this at every meal. As long as you’re eating enough calories to meet your daily energy needs, and sticking to a reasonably varied diet, getting enough protein is generally not a problem. It’s actually difficult to become protein deficient unless you quit eating altogether! If you have concerns, talk to your doctor or dietitian.
Vegetarian foods highest in overall protein content include legumes or pulses (dried beans and peas), soy products of various kinds (tofu, tempeh, meatless “meats”), eggs and dairy products for those who consume them, and some nuts.
Choose your proteins wisely!
A recent study suggested eating too much protein from red meat and dairy products increases your risk of fatal coronary heart disease. Participants in the study who ate the highest amount of vegetable protein sources such as beans, nuts, tofu, and peanut butter were found to be 30% less likely to die from heart disease. Fish and chicken were not linked to heart risks in the study.
Even if animal protein and vegetable protein have the same effects on your health, it’s probably what comes with the protein that makes it a more – or less – healthy choice.
Use the following table to help you make wise protein choices:
|Examples of Common Foods Containing Protein||Protein (g)||Calories||Fat (g)||Carbs (g)|
|Animal protein foods:|
|Beef, rump steak, lean, grilled, 100g||32g||200||7g||0|
|Chicken, breast, baked, no skin, 100g||28g||157||5g||0|
|Milk, full cream, 1 cup, 250 ml||8g||160||9g||12g|
|Milk, skim, 1 cup, 250 ml||9g||83||0.3g||12g|
|Yoghurt, natural, 200g||12g||160||8g||10g|
|Yoghurt, natural, low-fat, 200g||12g||160||3.8g||17g|
|Cheddar cheese, 30g||8g||120||10g||0|
|Cottage cheese, low-fat, 30g||4g||27||0.8g||1g|
|Egg, large, boiled or poached||7g||81||6g||0g|
|Tuna, 95g tin||18g||78||1g||1g|
|McDonald’s Big Mac||25g||481||25g||35g|
|Hungry Jacks Whopper||29g||656||39g||46g|
|Plant protein foods:|
|Red kidney beans, 200g||10g||170||1g||31g|
|Soy beans, 200g||17g||210||11g||6g|
|Lentils, cooked, 200g||18g||232||1g||40g|
|Peanuts, roasted and salted, 30g||7g||176||15g||6g|
|Soy milk, 1 cup, 250 ml||8g||161||8g||12g|
|Potato, boiled, 100g||2g||87||0||20g|
|Rice, white, cooked, 1 cup, 160g||4g||208||0||45g|
|Special K cereal, 1 cup, 40g||8g||150||0||28g|
|Weet-Bix, 2 biscuits, 33g||4g||117||0||22g|
|Broccoli, boiled, 2 florets, 45g||1g||16||0||3g|
|Apple, average all types, small||0.3g||55||0||15g|
Refer to our food database for more extensive listings.