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Low carb diets have become hugely popular in recent years, and the range of products and recipes advertising their lower-carb or keto virtues has exploded.

What does it all mean, and should we all be going low carbohydrate?

What is low carb?

Carbohydrates are energy-yielding nutrients (macronutrients) that are the body's primary source of energy.

The tricky thing about ‘low carb’ is that there isn’t an agreed consensus on what ‘low carb’ actually means. Most dietary guidelines recommend that carbohydrate contributes between 45–65 per cent of your energy intake, which is a pretty big range. This is generally considered a moderate or balanced carbohydrate intake. In many research studies, a low carbohydrate diet generally offers between 20–45 per cent of its total energy from carbohydrate, which is also a pretty big range.1

So, because the definition of a low carb diet depends on the proportion of energy that it contributes to, the amount of carbohydrate you can consume on a low carbohydrate diet is very dependent on your energy needs.

  • For example, for a 70kg woman who exercises three times a week and needs 9,240kJ (2,200 calories) per day, a low carbohydrate diet consists of consuming 110–250g of carbohydrate per day.
  • In contrast, a 90kg, active man, who needs 12,600kJ (3,000 calories) per day, can afford to have 150–340g of carbohydrate per day and still be adhering to a low carbohydrate diet.

Why go low carb?

There are many reasons why low carbohydrate diets have become so popular.

Energy management

Since the re-emergence of the Atkins diet in the mid-90s, there has been a cultural push toward reducing carbohydrate to manage energy intake and weight. As carbohydrates are a key nutrient that fuels your body, removing or reducing high carbohydrates food can reduce your energy intake.

For example, if you swap from having one cup of cooked basmati rice with your dinner (approx. 400 calories) to 1 cup of cauliflower rice (approx. 40 calories), the energy content of your meal reduces and can contribute to an energy deficit, which is required for weight loss.

While this sounds encouraging, it’s important to remember that your overall energy intake is an essential component to weight loss. If you end up consuming lots of fat and protein-rich foods instead of carbohydrates, and your total energy intake is too high, long-term, sustainable weight loss won’t be achieved, regardless of how low your carb intake is.

Managing type 2 diabetes

One of the most promising aspects of the research into low carbohydrate diets is that they appear to improve markers of insulin resistance. Several reviews of the dietary approaches to manage type 2 diabetes indicate that moving from a moderate or high carbohydrate diet to a low carbohydrate diet can improve blood glucose control and even push diabetes markers into remission.2,3

As with any dietary pattern, the results will only last as long as we continue that dietary pattern. This is why it’s important to work with a dietitian to determine the right load of carbohydrate that can be sustained within your lifestyle, and avoid falling for myths about diabetes and nutrition.

Ketogenic diet

‘Keto’ or a ketogenic diet is a common reason why people are looking for low carb options. A ketogenic diet is very low in carbohydrate (less than 10 per cent of energy coming from carbohydrates) and it requires the elimination of a range of healthy whole-food groups including grains, legumes, fruit, starchy vegetables and dairy products. The removal of these foods can have implications for gut health, nutrient deficiency and metabolic health, which is why it’s important to consult with a healthcare professional before commencing a restrictive dietary pattern.

Naturally lower carb foods

If you are wanting to reduce your carbohydrate intake, these foods are naturally lower in carbohydrate and can be nutritious options.

Low carb vegetables

  • Spinach
  • Bok choy
  • Broccoli
  • Green beans
  • Carrots
  • Parsnips
  • Turnip
  • Tomato
  • Cauliflower
  • Peas
  • Capsicum
  • Onion
  • Cucumber
  • Radish
  • Pumpkin
  • Zucchini
  • Eggplant
  • Mushroom
  • Wombok
  • Cabbage
  • Snow peas

Low carb fruit

  • Blueberries
  • Strawberries
  • Blackberries
  • Plums
  • Kiwi fruit
  • Cherries
  • Rockmelon

Nuts and seeds

  • All nuts and seeds are low in carbohydrate.

Meat, poultry, seafood, eggs and soy

  • All foods in these groups are low in carbohydrate unless they are crumbed, battered or marinated.

Dairy

  • Milk
  • Yoghurt – unsweetened
  • Cheese

Remember

Lower carb doesn’t mean no carb. Nearly all foods contain carbohydrate as it’s a necessary nutrient for metabolism.

‘Low-carb’ carbohydrate foods

In response to the recent rise in low carb dietary patterns, many food manufacturers have started to offer lower carbohydrate versions of high carbohydrate food. You may have seen products like:

  • Lower carb potatoes
  • Lower carb bread
  • Lower carb wraps
  • Low carb chocolate bars.

Many of these products are not low in carbohydrates, but they are lower in carbohydrate than the original product. For instance, some lower carb breads still consist of 27 per cent carbohydrate.

To lower the proportion of carbohydrate, some lower carb options are higher in protein and in fat, which may have implications for your energy intake. For example, a wholemeal bread roll may be 188 calories, while a low carb bread roll is 265 calories. This difference is small, but it’s important to be conscious of whether choosing low carbohydrate meets your energy needs and manages your appetite effectively.

Should I go low carb?

While there may be some benefits to lowering energy intake or improving type 2 diabetes, there is no one-size-fits-all dietary approach. Reviews of the research indicate that there is no significant difference to weight or cardiovascular health outcomes for people following a low carbohydrate diet and those following a moderate carbohydrate diet.1 It comes down to what you can do consistently.

The best way to find out which dietary pattern is right for you is to work one-on-one with an accredited practising dietitian. They can work with you to find out the carbohydrate load that you can stick to and that will help you achieve your goals.

Header image: Unsplash

References

  1. Naude CE, Schoonees A, Senekal M, Young T, Garner P, Volmink J (2014) Low Carbohydrate versus Isoenergetic Balanced Diets for Reducing Weight and Cardiovascular Risk: A Systematic Review and Meta-Analysis. PLoS ONE 9(7): e100652. https://doi.org/10.1371/journal.pone.0100652
  2. Ajala O, English P, Pinkney J, Systematic review and meta-analysis of different dietary approaches to the management of type 2 diabetes, The American Journal of Clinical Nutrition, Volume 97, Issue 3, March 2013, Pages 505–516, https://doi.org/10.3945/ajcn.112.042457
  3. Goldenberg J Z, Day A, Brinkworth G D, Sato J, Yamada S, Jansson T et al. Efficacy and safety of low and very low carbohydrate diets for type 2 diabetes remission: systematic review and meta-analysis of published and unpublished randomized trial data BMJ 2021; 372:m4743 doi:10.1136/bmj.m4743

About the author

The Healthy Eating Hub

This article was written by an Accredited Practicing Dietitian from The Healthy Eating Hub. The Healthy Eating Hub is a team of university-qualified nutritionists and dietitians who are passionate about helping people develop long term healthy eating habits through offering evidence-based and practical nutrition advice that people can put into practice straight away.

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