Which is more filling, protein or fibre?

Protein has been everywhere lately. You may have seen food products promoting high protein content, or reels online telling you how to boost your intake.

One of the ways protein supports our health is by helping a meal fill us up (satiation) and keeping us feeling fuller for longer between meals (satiety). It does this by influencing our appetite hormones and other metabolic processes.

But protein is not the only nutrient that helps with satiation and satiety. And if we focus too much on protein, we may miss the big picture and forget about other important nutrients.

It’s time to put the spotlight on dietary fibre and where to get it – especially as most of us aren’t eating enough.

Let’s take a look at how much protein you need, how much fibre, and how they compare in keeping you feeling full.

First, do we really need more protein?

The recommended dietary intake of protein for Australian adults aged 19–70 years is 46 grams a day for women and 64g a day for men.

Across your day, this could look like eating:

• 200 millilitres of natural yoghurt (10.6g protein)
• a beef burger (31.5g protein)
• 20g almonds (3.9g protein)
• and for men – an extra 75g of cooked chicken thigh (18.2g protein).

Data from the 2023 National Nutrition and Physical Activity Survey indicated that, on average, Australian women are eating 78.7g protein a day and men are eating 103.4g protein a day. This means most Australian adults are eating plenty of protein, above the recommended daily intake, even for those aged over 70 who need more.

What about fibre?

Dietary fibres are a class of carbohydrates that are resistant to human digestive enzymes. This means they’re not digested and absorbed like other carbohydrates (such as sugars and starches), allowing them to play other roles in the body.

Among the many beneficial health effects of dietary fibre – such as reducing the risk of heart disease, improving cholesterol levels and supporting healthy gut bacteria – it can also help to keep you feeling fuller for longer after a meal.

Not all dietary fibre is the same. Different types of fibre perform various functions in the body, based on how soluble they are in water (solubility), how much they thicken into a gel (viscosity), and whether gut microorganisms can ferment them (fermentability).

For example, the soluble viscous fibres present in many fruits and vegetables slow the passage of food through the stomach and intestine, helping to prolong satiety – that feeling of fullness between meals. They also slow the release of sugar into the blood after eating carbohydrates, which helps regulate blood sugar levels and delay hunger.

Both soluble viscous fibres and insoluble fibres (found in vegetable skins and wholegrain bread, for example) contribute to the physical expansion of the stomach after eating. This sends signals of fullness and satiation to the brain, helping us know when to stop eating.

Dietary fibres may also influence the production of appetite hormones, which promote satiety.

How much fibre do we need?

In Australia, it’s recommended adult women eat 25g of fibre a day and adult men eat 30g.

To get extra health benefits – such as reducing your risk of chronic (long-term) disease – a higher fibre intake of 28g a day for women and 38g a day for men is recommended.

Australians are not eating enough fibre

Data from the 2023 National Nutrition and Physical Activity Survey indicated that, on average, Australian women are eating 19.2g a day and Australian men are eating 22.3g a day. Both are well below the recommended values.

Improving fibre intake is not just about increasing the overall quantity you eat, but also about getting a variety of different fibres with different properties.

You can get more soluble viscous fibres into your diet by eating fruit (such as apples, oranges and bananas), oats, legumes and pulses (including beans and chickpeas), and vegetables (think: peas, avocado, sweet potato and carrot).

Or you can take fibre supplements, such as Metamucil or Benefiber. People who can’t eat gluten should consult with a health-care professional first, as some supplements may contain gluten.

Read more: Some vegetables are pretty low in fibre. So which veggies are high-fibre heroes?

You can increase your intake of insoluble fibres by eating the skin of fruits and vegetables, wholegrain products (such as bread, pasta, brown rice and quinoa), nuts, seeds, and wheat or rice bran.

To get fermentable fibres in your diet, include things such as oats, legumes, unripe bananas, or cooked and cooled potato, rice, or pasta (cooking and cooling changes the structure of some of the carbohydrates, making them resistant to digestion).

Some good overall tips for improving your fibre intake are to:

• choose wholegrain, wholemeal and/or high fibre varieties of grain-based foods like bread, rice and pasta whenever possible

• enjoy a variety of different fruits and vegetables, aiming for two pieces of fruit and five servings of vegetables each day

• eat nuts and seeds as a snack

• look for ways to include legumes and different types of wholegrains with meals.

If you are planning on increasing your fibre intake, you should take it slow and also drink plenty of water to avoid potential digestive problems.

Read more: Money’s tight but food prices are up. Here’s how to save on your grocery bill

So which is more filling, protein or fibre?

Both contribute to increased feelings of fullness through multiple mechanisms.

And while protein has been generally accepted as the most important nutrient for satiety, one small study comparing fibre and protein directly found they were just as good as each other when it came to that lasting feeling of fullness between meals.

We would need more research directly comparing the two to determine which is more filling.

The takeaway

Choosing foods that are rich in either dietary fibre or protein – or even better, both, such as lentils, beans and nuts – will help to fill you up and keep you feeling fuller for longer between meals.

But since most Australians aren’t eating enough dietary fibre, increasing your fibre intake is likely to be more beneficial for your overall health than increasing how much protein you eat.