Low Carbohydrate, High Fat for Type 2 Diabetes: An Evidence-Based Assessment

January 27, 2017
Feng-Yuan Liu


For those of you who know me personally or professionally, you will know that I am extremely passionate about metabolic nutrition and helping my clients understand the science behind my recommendations. Always.

With all the information, misinformation and misrepresentation of information spreading faster than wildfire, people’s minds are also exploding at the same velocity.

One topic that seems to take the spotlight is the “Low Carbohydrate, High Fat” way of eating.

I have written briefly about this previously to correct some misinformation around it – you can read it here.

However, recently I read a piece written by the Dietitians’ Association of Australia (DAA) published under their “Hot Topics”. It was their response to the Low Carb High Fat way of eating and Type 2 Diabetes. You can access their full article here.

In keeping with evidence-based practice I was very confused with how the DAA came to some of their conclusions. This sort of misinformation, or rather “misrepresentation” of information is something I personally find discouraging, as it only fuels the public confusion, and frankly, makes it very difficult for us dietitians to be taken seriously.

In this blog, I wish to take you through their piece section by section, so we can really break it down, and get to the bottom of this “Hot Topic”.


What are the Goals of Diabetes Care?

The DAA says:

“When you have diabetes mellitus, the aim is to manage your blood glucose levels, your blood fats and blood pressure as best as possible. Advice about food and eating is very important because in both the short term (3-6 months), and the long term (2 or more years), it influences your health and how you feel.

Advice should always be supported by the best quality science and be individualised for each person to match their health goals, personal and cultural preferences, their access to healthy choices, and their readiness and willingness to change. To this end, there is no single optimal diet for all people who have diabetes – there are many different ways of eating well.


I say:

Nutrition plays an integral role in the management of blood glucose and in the prevention of complications relating to poorly managed blood glucose. Whilst individualisation is done on a one-on-one basis in consultation, there are some universal rules that apply which we must take into consideration when making our recommendations.

Rule #1:

Type 2 diabetes is characterized by excess glucose in the blood, and an over-stimulation of the pancreas to produce extra insulin to deal with the glucose since the cells of the body has become resistant to the actions of insulin and need more of it to do the same job.

Rule #2:

Of the 3 macronutrients – proteins, carbohydrates and fats – carbohydrates have the GREATEST impact on blood glucose levels and therefore, on insulin production

Rule #3:

Of the 3 macronutrients – proteins, carbohydrates and fats – fats have the LEAST impact on blood glucose as it does not give rise to blood glucose and therefore, on insulin production.

When you couple these universal rules of basic human physiology with quality science [1] [2] [3] [4] you will find that there is an abundance of evidence to support carbohydrate restriction in the management of Type 2 Diabetes.


What is a Low Carbohydrate Diet?

The DAA says:

“Well, that’s part of the problem . . . ‘low carbohydrate’ is poorly defined.

In research, some have used ‘Very Low Carbohydrate Ketogenic Diets’ (VLCKD) with amounts from 20-50g carbohydrate per day (less than four ‘portions’). These diets often omit whole food groups and make it impossible to meet all known nutrient and fibre targets, and therefore could not be recommended for diabetes management in the long term.

Others have suggested that ‘Low’ is <130g/day (26% of energy based on a person’s intake of 8,400kJ/day). ‘Moderate’ carbohydrate falls between 130-230g/day (26-45% of energy based on a person’s intake of 8,400kJ/day) and then ‘High’ carbohydrate is >230g/day (45% of energy based on a person’s intake of 8,400kJ/day).


I say:

To begin with, I would like to remind you all that in a previous article I wrote, I debunked the claim that eating a diet low in carbohydrate makes it “impossible” to meet fibre targets (I recall that I did a quick calculation to showcase how we can meet fibre targets whilst eating low carbohydrate). In terms of other known nutrients: I cannot think of a single one that cannot be adequately met on a diet low in carbohydrates. Can you?

Then, when we look at the definition of “low carbohydrate”, more questions arise. The DAA appears to be confused.

The DAA quoted that in research, some have used the definition of low carb as 20-50g/day, whereas others believe that low carb is anything less than 130g/day.

What they didn’t make clear was the fact that both figures were pulled from the same research paper [5]. What is more interesting is the fact that in this paper written by Feinman et al [5], they clearly defined the parameters as being 20-50g/day as “very low carbohydrate ketogenic (VLCKD)” and <130g/day as “low carbohydrate”. They clearly stated in the body of their paper that they defined it this way to eliminate ambiguity and that “each definition is based on use in multiple publications by those authors who have performed the experimental studies”[5].

This says to me that they took the care to ensure that the parameters they have defined and used to review research were consistent.

What was most conveniently left unsaid what the fact that the Paper referenced by the DAA [5] was actually a critical review of the current evidence base on low carbohydrate nutrition and Type 2 Diabetes, and from this paper, 12 compelling findings were made and summarized:

#1: Dietary carbohydrate restriction has the GREATEST effect on decreasing blood glucose levels

#2: During the epidemics of obesity and type 2 diabetes, caloric increases have been due almost entirely to increased carbohydrates

#3: Benefits of dietary carbohydrate restriction do not require weight loss i.e. you do NOT need to see weight loss to see benefits to glycaemic control (blood glucose control).

#4: Although weight loss is not required for benefit, carbohydrate restriction is still the best dietary intervention for weight loss

#5: Adherence to low-carbohydrate diets in people with type 2 diabetes is at least as good as adherence to any other dietary interventions and is frequently significantly better

#6: Replacement of carbohydrate with protein is generally beneficial

#7: Dietary total and saturated fat do not correlate with risk for cardiovascular disease

#8: Plasma saturated fatty acids are controlled by dietary carbohydrate more than by dietary lipids

#9: The best predictor of microvascular and, to a lesser extent, macrovascular complications in patients with type 2 diabetes, is long term glycaemic control

#10: Dietary carbohydrate restriction is the most effective method (other than starvation) of reducing serum triglycerides and increasing high-density lipoprotein

#11: Patients with type 2 diabetes on carbohydrate-restricted diets reduce and frequently eliminate medication. People with type 1 usually require lower insulin

#12: Intensive glucose lowering by dietary carbohydrate restriction has no side effects comparable to the effects of intensive pharmacologic treatment

The very article that the DAA chose to reference provided all the evidence needed to show the benefits of carbohydrate restriction for diabetes, yet data was “cherry-picked” in their article on the DAA website to suit their needs.

They then mislead their readers further when they went on to quote a paper by Naude et al (2014) [6] concluding that there are no long term benefits of low carb on weight loss. Not only was this paper completely irrelevant to Type 2 diabetes (especially since Feinman’s paper [5] convincingly found that weight loss was not needed to improve glycaemic control), they failed to highlight that in this paper by Naude [6], the defining parameter of “low carb” was 225g of carbohydrates a day. Not only is this edging on high carb even by Australian Dietary Guidelines standards, I don’t know ANYONE who would consider 225g of carbohydrates a day as low carb. To put it in lay-man terms, that’s 15 slices of bread a day!

Cherry-picking research and data – is this really what we call “evidence-based practice”?

C’mon guys!

Anyway, let’s read on.


The DAA says:

“One of the main problems is that it can be difficult to translate this Low Carbohydrate diet into foods, without dramatic changes to the types of foods normally eaten. Unfortunately, this can create challenges for people who live with others (such as in a family setting) to adjust the diet to suit everyone in the household and it may risk some members nutritional needs, particularly children and adolescents.

Also, some people may incorrectly believe that this type of diet means they can simply eat more meat. This is not true. For health reasons, the Australian Dietary Guidelines place a limit on meat consumption at ~455g/week for adults. People with diabetes may also be misled by the idea of replacing some carbohydrates with foods high in saturated fat – however, research shows this can actually increase insulin resistance.”


I say:

How sustainable a habit, behaviour, choice or decision we make is, has nothing to do with WHAT that decision is, but everything to do with WHY we made that decision, and HOW important that decision is to us. If our client came to us for their diabetes, and if their goal is to get their diabetes under control, then our role is to help them achieve that goal clinically. The social side of it is up to them to work out. I am sure that any competent dietitian would be able to provide suitable alternatives to help clients maintain some level of meal-time normality at home, but our jobs first and foremost is NOT to keep peace at home, but rather to help our clients manage their diabetes.

The DAA’s argument about eating more meat first and foremost defies what a nutritionally balanced Low Carb High Fat diet is all about – after all, it is High Fat, not High Protein. Having said that though, they made a ridiculous assumption that low carb = high protein, then justifies this decision as being a bad one for very peculiar reasons. They mentioned that “for health reasons” meat consumption should be limited – what health reasons are these, exactly? They do not say. Furthermore, increasing protein does not always have to be an increase in meat – it can be in fish or eggs or tofu…are they also restricted for the same “health reasons” that the DAA failed to elaborate on?

And I don’t know if anyone has actually bothered to do the calculations – but 455g a week of meat…Is this cooked weight or raw weight? We all know that meat decreases in weight through the cooking process – so if this is raw weight, then it would work out to be a lot less in cooked weight.

To give them the benefit of the doubt, I will do my calculations based on “cooked weight”.

So that works out to be 65g of meat a day (1/3 to 1/4 of a standard sized piece of steak). That works out to be 15-20g of protein a day. Yes you read right – apparently, we are only allowed to have 15-20g of protein a day. Now, we also know that protein requirements vary dramatically based on body composition (muscle mass, fat mass, etc), activity levels and physical goals. However I don’t know of ANY scenario where a person’s protein intake should be only 15-20g a day.

If I have misinterpreted the DAA, then I stand corrected, but the ambiguity opens itself right up for this kind of misinterpretation (and I AM a dietitian! Imagine how the public must feel?).

Also – saturated fats will not make someone more insulin resistant – unless the person wasn’t well informed to restrict their carbohydrate intake in the first place.


Important Information about Carbohydrate Foods

The DAA says:

“The amount, type and frequency of carbohydrate foods in a diet pattern is an important consideration in the management of diabetes mellitus. Foods that are considered carbohydrate choices are many and varied, and are of differing quality. Low GI food choices (GI<55) are important in selecting the right carbohydrate foods for you. And overall, the reduction in total energy (kilojoule) intake is key to glycaemic control in most people with diabetes (type 2). Dietitians also recommend people with diabetes spread their carbohydrate food choices over the day, to assist with glycaemic control.

According to Diabetes Australia, very low carbohydrate diets are not recommended for people with diabetes. The organization states: ‘If you eat regular meals and spread your carbohydrate foods evenly throughout the day, you will help maintain your energy levels without causing large rises in your blood glucose levels’ (Diabetes Australia website, 2015). Diabetes Australia recommends people with diabetes eat moderate amounts of carbohydrate and include high-fibre foods that also have a low glycaemic index (GI).”


I say:

The amount, type and frequency of carbohydrate foods is definitely an important consideration in the management of diabetes. However:

I believe that the amount should be tailored to what will bring about a reduction in blood glucose and insulin secretions – this might be 20g a day for one person, and 90g a day for another;

I believe that someone with Type 2 diabetes does not need to consume carbohydrates regularly to assist with glycaemic control; and

I believe that total energy reduction is not the answer.

How do I know? Because of close to a decade’s clinical experience and multiple peer-reviewed Randomized Control Trials that support this belief [1] [2] [3] [4] [5].

Furthermore, I am a bit sceptical of referencing Diabetes Australia for dietary advice – I thought the DAA were the leaders in nutrition? Why are we looking to other government bodies for references on how to eat instead of quoting actual research?


Are carbohydrate foods needed by the body?

The DAA says:

“While there are specific requirements for amino acids (from proteins) in the diet, and essential fatty acids (from fats), there is talk that there is no specific requirement for carbohydrate.

This is not true. Both your brain and red blood cells require glucose and while some can be supplied by breaking down proteins in your body, there are a number of reasons why this is not beneficial and is specifically not recommended – for example, during childhood (due to growth requirements) and during pregnancy. The long-term effect of placing this demand on the body has also not been tested and there is evidence to suggest that performance in mental and physical tasks could be affected. Therefore, a diet that is very low in carbohydrate may not be physically or mentally sustainable as a diet pattern.”


I say:

I think the biggest flaw in this statement is mistaking the NEED for glucose with the need to CONSUME it through food. Whilst I nor any scientist will argue that our brain and muscles need glucose (even though we can use ketones too), we do not need to CONSUME it – funnily enough there is a nifty little process known as gluconeogenesis whereby the body can synthesis glucose from protein and fats.

Regarding sustainability – this I have addressed earlier, so will refrain from repeating myself. However what I would like to point out is that research is showing that adherence to a low carbohydrate protocol is greater than the currently recommended “low fat” protocol [7].


What are Australian’s Eating?

The DAA says:

“From the latest National Nutrition Survey, data suggests on average Australians are consuming about 222g of carbohydrate per person per day, making up 43.5% of total energy intake (Australian Bureau of Statistics, 2011-12). This indicates a ‘Moderate’ carbohydrate intake across the population. Furthermore, for Australians, this amount has decreased since the last National Nutrition Survey in 1995.”


I say:

So what I am seeing here is that on average, Australian’s are consuming 222g of carbohydrates a day, which the DAA has defined as “moderate carbohydrate intake”. Yet they were happy to reference a study [6] where 225g of carbohydrates were used as part of a “low carb” protocol. How can your definition of “low carb” be higher than your definition of “moderate carb”? It simply does not add up to me.

Furthermore, they also mentioned (which I will paste the excerpt below) that we should be consuming 50% of our total daily intake from carbohydrates (this works out to be 250g a day!)

“In its ‘Carbohydrates and Health Report’ (2015), the Scientific Advisory Committee on Nutrition (UK) recommended that the dietary reference value for total carbohydrates should be maintained at an average population intake of around 50% of total dietary energy.”

What I gather from all of this (and correct me if I am wrong), is that Australian’s are consuming LESS carbohydrates than what is recommended and Diabetes is one of the biggest health crisis here. Yet despite all the compelling evidence pro low-carb (and I mean actual low-carb) for diabetes management and prevention, we are still getting told that we should be consuming MORE carbohydrates? I know that I am not the only one failing to understand this logic.


A word on Saturated Fats

The DAA says:

“In ‘Low Carb, High Fat’ diets, a variety of fats have also been suggested as replacements for carbohydrate foods. Some LCHF diets promote foods like coconut oil and animal fats (such as lard and butter), often suggesting these are more ‘natural’ sources of fat. DAA believes this is misleading.

All fats are rich in energy (kilojoules) – containing twice the amount of kilojoules as either protein or carbohydrate – so if eaten in large amounts, can make weight control more difficult. The Australian Dietary Guidelines recommend Australians limit intake of foods high in saturated fat.

Foods high in saturated fat include:

Many biscuits, cakes, pastries, pies, processed meats, commercial burgers, pizza, fried foods, potato chips, crisps and other savoury snacks, butter, cream, cooking margarine, coconut and palm oil.”


I say:

Unless we are still living in the Dark Ages, I believe that nutritional science has progressed far enough that even lay people are understanding that maintaining health and achieving weight loss is not as simple as calorie in versus calorie out. We all know that whilst we can control calorie in (our food intake), our output is subject to so many hormonal and metabolic pathways that by simply reducing caloric intake and expecting our caloric output to stay the same and thereby help weight loss along is futile! [7]

Total quantity of fats aside, the worst part of all this is the fact that the Australian Dietary Guidelines are still telling people to avoid saturated fats because it supposedly poses a risk to heart disease. This is definitely what is most misleading, as numerous studies have been published to confirm the contrary [8] [9] [10].

Furthermore – the definition of Saturated fats by the ADG confuses me a lot – biscuits, cakes and pastries are by far considered sources of sugars more than they are of saturated fats, especially since a lot of commercially prepared biscuits, cakes and pastries now use vegetable oils instead of butter. And just a word on margarine – this is 100% NOT a source of saturated fats.


The Final Word (My Final Words)

As the governing body of (as the DAA quotes) over 6,000 members, I think you OWE it to each and every one of the members you represent to publish information that is accurate and evidence-based, first and foremost.

As the representative body of “leaders in nutrition” with the tagline “Leadership in Dietetics” I think you OWE it to the public to get your facts straight!

I mean, come on, potato chips is NOT a saturated fat! In fact, out of the entire list of foods you have stated, only butter, cream and coconut oil are actually rich sources of saturated fats. Palm oil has just as much monounsaturated fats as saturated, and the rest are all subject to how it was prepared, as those foods inherently are not foods rich in saturated fats.

As the ONLY accreditation body for dietitians in this country, I think you OWE it to all of Australia to stop promoting our title or qualification as the identifying factor of “expertise in nutrition” and start humbling down and actually looking at what is going on in the world of nutritional research so you can actually know whether or not your members are keeping up with the research or whether, like yourselves, they are just regurgitating the same old (and wrong) guidelines over and over to clients, making absolutely no difference to the global health crisis that is Type 2 Diabetes.




[1] Daly ME, et al. (2006) Short-term effects of severe dietary carbohydrate-restriction advice in Type 2 diabetes–a randomized controlled trial.

[2] Westman EC, et al. (2008) The effect of a low-carbohydrate, ketogenic diet versus a low- glycemic index diet on glycemic control in type 2 diabetes mellitus.

[3] Volek JS, et al. (2009) Carbohydrate Restriction has a More Favorable Impact on the Metabolic Syndrome than a Low Fat Diet.

[4] Eric C Westman and Mary C Vernon (2008) Has carbohydrate-restriction been forgotten as a treatment for diabetes mellitus? A perspective on the ACCORD study design.

[5] Richard D. Feinman et al (2015) Dietary carbohydrate restriction as the first approach in diabetes management: Critical review and evidence base.

[6] Naude et al (2014) Low Carbohydrate versus Isoenergetic Balanced Diets for Reducing Weight and Cardiovascular Risk: A Systematic Review and Meta-Analysis.

[7] Gunnars, Kris (from Website: Authority Nutrition – https://authoritynutrition.com/low-carb-diets-healthy-but-hard/)

[8] Patty W Siri-Tarino, Qi Sun, Frank B Hu, and Ronald M Krauss (2010) Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease

[9] Russell J de Souza,Andrew Mente,Adriana Maroleanu,Adrian I Cozma,Vanessa Ha, Teruko Kishibe,Elizabeth Uleryk,Patrick Budylowski,Holger Schünemann,Joseph Beyene, Sonia S Anand (2015) Intake of saturated and trans unsaturated fatty acids and risk of all cause mortality, cardiovascular disease, and type 2 diabetes: systematic review and meta-analysis of observational studies

[10] Zoë Harcombe,Julien S Baker,Stephen Mark Cooper, Bruce Davies, Nicholas Sculthorpe, James J DiNicolantonio, Fergal Grace (2014) Evidence from randomised controlled trials did not support the introduction of dietary fat guidelines in 1977and 1983: a systematic review and meta-analysis