What’s the latest?

Low carbohydrate, high fat diets have recently re-emerged (having last been popular in the 1970’s), and have caught the attention of some members of the scientific community and the public.

What is a low carbohydrate diet?

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 a healthy eating plan or 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).

The latest Australian Health Survey, data suggests on average Australians are consuming about 222g of carbohydrate per person per day, making up 43.5% of total energy intake.

Are carbohydrate foods needed by the body?

Carbohydrates are an organic compound made up of carbon, hydrogen and oxygen. They are the main energy source for our body, which gets used first (before protein, fat and alcohol). Both your brain and red blood cells require glucose which is derived from carbohydrate digestion and while some can be supplied by breaking down proteins in your body, carbohydrates spare protein which helps preserve muscle mass and do this more efficiently than fats. Carbohydrates also provide nutrients for the good bacteria in our intestines that help us digest our food.

Carbohydrate foods supply many nutrients. These include B vitamins and fibre from grains, and vitamins, minerals, dietary fibre and other plant components such as antioxidants from fruit and starchy vegetables. So without careful planning, it can be more difficult to meet nutrition needs on a low carbohydrate diet.

What are the Findings?

A recent systematic review and meta-analysis of a variety of diets (Low Carbohydrate, Low Glycaemic Index (GI), Mediterranean and High Protein) for people with diabetes, found some benefits for a low carbohydrate diet in the short term. Including:

  • Some improvement in HbA1c (although the Low GI diet and the Mediterranean diet performed better on this measure)
  • Weight loss (although those in the Mediterranean diet group lost more weight)
  • Improved HDL cholesterol (also seen in the Low GI and Mediterranean diet groups)

When it comes to weight loss, Naude et al (2014) examined nineteen trials (n=3,209) and were also able to confirm that weight loss occurs in the short-term, irrespective of the proportion of macronutrients. They found no difference between low carb diet or “balanced diets” in regards to weight loss (or cardiovascular risk factors) even when participants are followed up for up to two years. There was also no difference in weight loss or cardiovascular disease risk factors in participants who were overweight or obese or in those with or without type 2 diabetes.

Also, it may be incorrectly believed that this type of diet means they can simply eat more meat but Australian Dietary Guidelines places a limit on red 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.

Consistent evidence indicates that in general, dietary patterns higher in plant-based foods such as vegetables, fruits, whole grains, legumes, nuts and seeds, and lower in red meat are more beneficial for overall health. This type of diet also has a lower impact on the environment and is therefore more environmentally sustainable as a recommendation for the population.

Acknowledgement: DAA Hot Topics 2017, References upon request.

This article is produced by the Nutrition Department: Theresa Dimitrakakis (APD), TinMiMi Maung (APD), Wendy Vaiano (APD), Katherine Adam (APD), Alex Salmon (APD), Lauren Snowden (APD)

Any comments or questions can be forwarded to the nutrition department: 9411 7550.