Discussion on low carb diets

Guest Post Sally Marchini, Dietitian

By popular demand I think that this topic deserves a blog to help explain some of the ‘stuff we hear’ around carbohydrates and type 2 diabetes.

I’d also encourage people with type 1 diabetes to read this, because some of the points made are also relevant for us!

Up front I will remind readers that everyone has individual requirements and should see an Accredited Practising Dietitian for a personalised consultation. This is a ‘general guide’ only.

Firstly, we need to understand what ‘low’ means in such a context. In my experience as an Accredited Practising Dietitian, people tend to associate ‘low’ with ‘virtually no’ carbohydrate. We’ll also look at some of the evidence that shows that ‘low’ carb diets can help with glucose control in type 2s, and why when drugs (other than metformin or SGLT2-inhibitors) are introduced it’s important to ensure more (quality) carb intakes as advised by your health professionals. And lastly (but certainly not leastly) we’ll review how, based on the Australian Dietary Guidelines, it’s possible to have a nutritionally balanced diet while watching your carb intake.

What does ‘low’ carbohydrate mean?

If you ask some people what they think ‘low carb’ means, you may hear that it’s about cutting carbohydrates out as much as possible. Straight up as a dietitian my alarm bells ring as carbs feature in all five of the food groups that we need for nutrients to ensure our wellbeing:  vegetables (starchy vegetables like potato, sweet potato and corn), fruit, dairy, protein (when the likes of legumes are included, and especially in vegetarian diets) and of course, the important grain/cereal foods.

The American Diabetes Association defines a low-carb diet as 130g of carb per day.  Does that surprise you??   The ‘trick’ with low carb diets is therefore to know how to choose your carbs wisely so that you’re still meeting your nutrient requirements, and also to know what to replace that carb energy with (remembering that carbs, proteins and fats make up our daily energy intake) so you don’t get too hungry and be encouraged to ‘cheat’.

Remembering that there’s 15g of carbohydrate in an ‘exchange’ or ‘serve’ that gives us close to 9 carb serves across the day.

If you’re on medication that helps your body to produce more insulin, or you’re providing insulin yourself on a fixed dose then this idea is dangerous to your health so please speak to your health professionals before making any changes to your diet.

Some benefits of lower carbohydrate diets

Of course we know that all carbohydrates break down to glucose which is the fuel needed by our bodies, but in modern diets often too much (and poor quality) of this ‘fuel’ is provided which can cause stress to our organs and worsen our diabetes control.  So understanding the benefits of a lower carbohydrate diet can help us to stick with it for longer and balance the rest of our diets more easily.

Some of those benefits may include:

  • Lower incidence of high blood glucose levels (hyperglycemia)
  • Lower amounts of medications need to control hyperglycemia
  • 130g/day is a sustainable amount, meaning it’s easier to stick to in the longer term
  • Putting your pancreas under less stress to produce insulin, thereby helping it to keep working for longer
  • By ensuring your 130g/day is nutritious and low-GI carb you may also improve your blood fat levels (cholesterol/triglycerides) which will  lower your risk of cardiovascular disease
  • It doesn’t necessarily lead to weight loss – that depends on your total energy intake.

How do you manage it best?

Again I will mention how important having a personalised consultation with your Accredited Practising Dietitian is because everyone is different in many ways. Here I will make suggestions that I hope will help to get your head around combining the idea of low carb into your daily routine while still meeting the nutritional requirements as outlined in the Australian Dietary Guidelines foundation diet (see page 2).

In a nutshell, it’s about only choosing your carb sources from the 5 food groups and balancing that out with quality proteins and healthy fats. I encourage you to re-read the previous blogs I’ve written on those topics as highlighted.

Remembering that 130g/day equates to close to 9 carb exchanges/serves, your day might start to look a bit like this:

Breakfast:  ¼ cup of raw rolled oats (1 serve carb) served with 125ml light milk (half a serve), a small banana (85g – 1 carb serve) and a tablespoon of LSA mix (for extra fibre/protein) = 2.5 serves total

Morning Tea:  A 100g tub of low-fat yogurt = 1 serve total

Lunch:  A sandwich made on wholegrain bread (the grainier the better – 2 serves) made with a protein serve and as much non-starchy veg as you can handle, either on the sandwich or as a side, using half an avocado as the spread (for your good fats), and a piece of fruit such as an apple or pear (both good low-GI fruits – 1 serve) = 3 serves total

Afternoon Tea:  A 30g handful of mixed unsalted nuts = not worth counting carb-wise

Dinner:  Remembering the balanced plate being one quarter carb, one quarter protein and half non-starchy vegetables, this works with so many meals.  Aim for your carb serve to = 2 serves total

Supper:  You’ve still got half a carb serve up your sleeve. I would encourage something like half a slice of grainy toast with peanut butter on it to give you the energy to get you through the night, but half a serve of low-fat dairy would also work well, or even a couple of squares of dark chocolate if you fancied it = 0.5 serves total

In this example you can see that we’ve incorporated 9 carb serves/exchanges and yet have included quality carbs at every meal.

Some final tips

  • Remember to include protein and some non-starchy veg with every meal.
  • Rice and pasta can be problematic a serve size is so small. Something I recommend that works for many people is to include the carb serves in the form of legumes (lentils, chickpeas, kidney beans, etc) in the pasta sauce and use low-carb alternatives such as those made from konjac root, or make pasta/rice out of vegetables such as grated zucchini or carrot or cauliflower.  I sometimes serve my pasta sauces on mashed cannellini beans and frozen spinach (warmed of course!) and find it’s very satisfying.
  • Don’t forget to exercise! If the point of minimising your carbs is to control your BGLs, then even as little as ten minutes exercise after meals can make a fantastic difference to your readings.  Do some self-experimenting about how much your BGLs drop after say 10, 20 or 30 minutes walking after meals, and then if you want to include more quality carbohydrates in some meals, you’ll know how to manage better.

I hope this has proved useful for you, and that you have a better understanding of how a low-carb (130g/day) might help with your diabetes control.  Of course please ask any questions below and I’ll be happy to address them for you.

Sally is owner of her own private practice (Marchini Nutrition), and has had type 1 diabetes for close to 40 years and coeliac disease for many years too. 

Edited by Helen Wilde, Moderator, Diabetes Can’t Stop me on 4/04/17


  1. Lyndal Parker-Newlyn on July 28, 2014 at 10:30 am

    Great article Sally- thanks for this clear explanation! reducing carbohydrates and ensuring quality and low GI choices need not be extreme!!

    • Sally on July 28, 2014 at 12:17 pm

      Thanks for your comment Lyndal 🙂

      You’re spot on! We all know too that extremes are not sustainable, and I tried to demonstrate how to make every mouthful count from a nutrient point of view.

      Wishing you a great week! Sal 🙂

    • Ina mclellan on November 28, 2017 at 7:32 am

      I m type 2on novamix 30 does the carb counting apply to this insulin because i am totally confused

      • Helen-Edwards on December 6, 2017 at 1:16 pm

        Hi Ina – each person is different so you need to check with your doctor or diabetes educator 🙂

  2. Cally Sumpter on July 28, 2014 at 12:48 pm

    Hi Sally – great message about carb QUALITY – couldn’t agree more!
    I find it interesting that the ADA defines low carb as 130g/day – I guess I always think “low carb” is more like the ridiculous <50g regimes.
    Perhaps we need to move away from "low carb" as our tag on these conversations and talk about moderate quantities of quality carbs as I'm sure people still misinterpret the difference. I feel the "low carb" tag lends weight to the notion that carbs are bad and we should limit them.
    Sometimes I sigh and wonder how we have lost our way with food, reading your article makes sense of it all – here's to consistent messages about GOOD FOOD!!
    Cheers, Cally (fellow APD)

    • Sally on July 28, 2014 at 3:01 pm

      Thanks for your positive response Cally! We definitely need more of these consistent messages about just eating GOOD FOOD. It’s great to be part of the new wave of dietitians who are openly discussing the practical ways to improve wellbeing through enjoying real food and avoiding processed food wherever possible.

      Best wishes, Sally.

  3. Tabitha Hume on July 29, 2014 at 6:56 pm

    Great article – nicely written and clear, thanks Sally. We have, in South Africa, a huge swing in popularity towards the EXTREMELY low carb diet with very high fat (mostly saturates) and moderate protein. We as dietitians are struggling to get people to listen to sense and not follow this, and the proponent of this crazy regime, Dr Tim Noakes (an exercise physiologist) is touting that all dietitians should be ‘fought against’ to ‘realise that the current Prudent guidelines are only in effect because of a conspiracy theory of us being paid by sugar companies and pharmaceutical companies! He’s having a field day and dietitians are suffering…
    What is your body’s stance on the very, very low-carb and high fat diet?
    Kind regards,

    • Sally on July 29, 2014 at 7:18 pm

      Hi Tabitha,
      Why don’t you send me an email at sally@marchininutrition.com? I’d be happy to chat with you about this complex topic offline.
      Best wishes, Sally 🙂

    • David Rhodes on November 17, 2014 at 6:05 am

      I disagree with you entirely. The conspiracy theories are not the reason he is speaking out about the low-fat diet, although in academia large companies definitely have a large influence on published studies and results interpretation. He has realised he was wrong, and feels a need to “get out of it” before the tide turns and he is tarred with the same brush. It is dietitians’ general refusal (although I have to admit it amusing for me to have seen how they have swung in the last two years) to let go of the idea that saturated fats are bad and that glycaemic index is more important than glycaemic load. There is also an ignorance amongst them that fruits contain some kind of magic nutrient not found in meats, eggs, dairy, etc. Remember fruits are very nutrient poor and sugar rich. Remember this – and here I refer to obesity and not diabetes, but the two are different iterations of the same metabolic disturbance – obesity is not caused because people overeat (or don’t move enough), people overeat because they are obese. It is only by providing the correct nutrients in the form of fat and protein, and not carbohydrates, that the tissues are not starved. You have a lot of work to do in terms of research. Repeating the same lies over and over and over does not turn them into the truth. Until dietitians they get to grips with the success of lchf and learn to embrace it – and believe me, many are already – then they will forever be in denial. I have researched heavily both sides of the fence, and humans either evolved to eat carbohydrates or they didn’t. If you look carefully as to how and at which sites even a small amount of carbohydrate influences LPL then, in my view, they didn’t. Think very carefully before you label Noakes.

      • Kerry Norton on January 10, 2015 at 4:27 pm

        Thanks for the link to this post Sally. I just thought I’d mention something in response to a reply: Dr Tim Noakes is a professor in South Africa teaching medicine students. My daughter’s wonderful paediatrician was taught by him. He’s not simply an exercise physiologist! He’s very highly qualified! And he’s not alone at all in his thinking. Dr Bernstein and Dr Atkins etc…

        Have you tried a real low carb diet (up to 50g per day)?
        I’d like to suggest it… Then see what the results are for yourself and you’ll be better placed to comment on these things.