The Problem With a High-Protein Diet

Thinking about loading up big-time on steaks, grilled chicken and tofu? High-protein diets may help you shed kilos at first, but dietitians say this way of eating doesn't do your body any favours long-term.

These days, it's hard not to stumble on high-protein diets. There are so many to choose from, and they're often touted as the be-all-and-end-all solution to better health and long-term weight management.

But what's the science behind these diets? Are they safe - and doable - in the long-term?

12WBT dietitian Georgie Moore says no. A high-protein diet may sound great, but it's simply another way of reducing your calorie intake by cutting out all sorts of other foods.

"A high-protein diet is just one more 'solution' to a weight problem. Any diet that causes you to eat less energy than you use will lead to weight loss," she explains.

However, she is dubious about the nutrition-rich foods you have to give up to go high-protein - often whole food groups such as carbohydrates and dairy - and the claims that often come packaged with many high-protein diets.

"For instance, the creator of one well-known high-protein diet claims you'll be free of almost all health issues including autoimmune diseases and even skin cancer!" says Georgie.

"He also declares that cholesterol is not necessarily linked to heart disease, but this is incorrect."

Busting the High-Protein Diet Myths

High-protein diets have been touted as the best fat burners - and it's true that protein is harder to digest so it burns more calories and keeps you full for longer.

Most people starting one of these diets also experience weight loss, because eating few or no carbs forces the body to use some of its glycogen stores instead, and also releases water.

But if your aim is healthy nutrition overall, such diets are unlikely to fulfil this brief and may even do you damage long-term.

In cutting out carbs from your diet, Georgie says you're cutting out the brain's favourite fuel.

Plus, consuming more protein than you need can lead to increased levels of uric acid in the blood, raising your risk of gout.

Too much protein in your diet can also lead to higher cholesterol levels.

That's not to say that everyone's diets should contain exactly the same amounts of the various macronutrients (such as protein or carbohydrates).

The Australian Dietary Guidelines were revised this year and now give more leeway for us to work out what we need based on our activity level, says Georgie.

"The guidelines have been updated to reflect that we move a lot less than we used to, and so the recommendation for carbohydrates in our diet has decreased," says Georgie.

"We need carbohydrates, but some of us require fewer than others. Those who are less active will need less fuel and thus fewer carbs in their diet, but generally speaking to keep your body functioning we cannot live without carbs."

So, in the same way that a diet based on a high protein intake is not recommended, neither is a low-carb diet.

The Role of Protein in our Diet

Protein is an important part of your diet: it's the building block of all muscles, organs, skins, bones and teeth.

It is also essential for muscle repair, regulates certain chemical reactions in the body and is a key player in helping the immune system fight off bugs.

"Protein is essential to build, grow, repair and maintain every bit of us, including hair, skin, blood - everything - so it's vital that we eat enough each day," says Georgie.

"The problem is, most Aussies eat way more in their diet than they actually need."

If you're on a diet like Atkins or the Dukan Diet, protein allowances may be unlimited.

But while high-protein fans or bodybuilders may operate under the belief that if a little is good for you, a lot must be better, Georgie says we need to be careful of how much we're consuming and how often.

"We do need a certain amount of protein in our diet, but we should 'drip-feed' it throughout the day.

"It's like alcohol: your body can only process certain amounts of protein in one go - about 25g to 30g in one sitting, which equates to about 100g of red meat or chicken," she explains.

"So, tucking into a 500g steak is not going to be of any more benefit to you than a 100g steak; your body just expels the protein it can't process right then."

How Much do we Need in our Diet?

This really depends on how active you are, but generally speaking we need 0.8g to 1.2g of protein per kg of body weight per day.

For a 70kg person, that would be around 70g per day, give or take a couple of grams.

What does that actually look like in our daily diet? Let's see.

Food item Protein
1 large egg 6g
100g chicken 28g
50g cooked lentils 8g
100g grilled salmon 22g
25g cheese 7g
  = 71g all up

Using the list above, you could easily space out your intake through the day - you could enjoy an egg on some grainy toast for breakfast, grilled chicken and a lentil salad for lunch and salmon for dinner with veggies, plus a little cheese for a snack.

"For non-vegetarians, as long as you're getting around 500g of red meat a week, two to three serves of fish per week and two to serves of low fat dairy per day, there's no need to be adding additional protein-rich foods beyond this to your diet," says Georgie.

Vegetarians need to be especially aware, though, of making sure they have enough protein in their diet, because the plant-based version is not as well absorbed.

To do this, they should include foods such as low-fat dairy, eggs, tofu, nuts, seeds and legumes in their diet.

Smaller amounts of protein can also be found in breads, grains and vegetables.

A Diet With Too Little... or Too Much

You'll soon notice the signs if you're not getting enough protein in your diet, says Georgie.

"Eating too little of this important macronutrient will lead to feelings of fatigue, poor wound healing and poor skin and hair - just poor health in general," she says.

And if you eat too much of it, or are on a diet that drastically reduces your carb intake, you can put your body into a process whereby the body is forced to start looking to use muscle for its carbohydrate source, which will lead to muscle depletion.

"Loss of muscle should not be a goal when it comes to weight management and health," says Georgie.

"This leads to a state known as ketosis. If the body is in ketosis for a prolonged period, it can lead to health problems such as heart disease, as well as lack of concentration, moodiness and low blood sugar levels.

"The kidneys filter excess protein, turn it into nitrogen and then we pee it all out, so having too much in your diet can cause serious kidney issues in the long term as well."

If you're unsure how much protein or other type of food you're taking in, try keeping a food diary - it's a great way to pinpoint where you may be going wrong nutritionally

Better Than the Rest

When you're looking at muscle repair, some forms of protein - known as HBV or "high biological value" - are considered better than others because they're more energy efficient, contain ideal amounts of amino acids and are more readily digested by the body.

The foods that are richest in HBV protein generally derive from animals, so that means including meat, eggs, milk and its by-products, such as whey, in your diet.

If you're vegetarian and looking for plant-based foods, then tofu, legume, lentils and nuts are all great sources of protein, so make sure your diet includes adequate serves of these.

Are Shakes and Bars Useful in our Diet?

Having a protein shake or bar after your weights session can be a great way to get an instant boost, with studies showing that consuming protein immediately after exercise sends it to your muscles more quickly.

But you shouldn't overdo them, warns Georgie. Ideally, she says, try to consume protein from real food after a workout if you're able to.

"Too much can mess with your kidneys. You're better off limiting bars or shakes to not more than one or two per day and trying to get most of your protein from real food instead, as part of your regular diet," she says.

"In the case of athletes who may find it hard to consume foods straight after training or just need a convenient protein hit, consuming them within the first 30 minutes after exercise is best, but you have a two-hour window in which you'd still gain the benefits of taking it in quickly."

• Want more info on what you should be eating in your diet to ensure it meets all your nutritional needs? The 12WBT Nutrition Plans are designed to do all the thinking for you.