Last Updated on 30 December 2023 by Brisbane Livewell Clinic
Macronutrients sustain us. Carbohydrates, fats and proteins all have a unique set of properties that influences health, and all are an essential source of energy. (1) It’s popular to alter the ratios of each macronutrient in the diet – there are even wide variances in recommendations by governing bodies around the world. This is partly because when expressed as a percentage of energy to the diet, human populations have historically survived on diets with greatly differing proportions of these macronutrients. (2) Ideas about macronutrient intake have also changed over recent decades.
Popular diet approaches like low fat foods and a low fat diet had a big focus in the latter part of last century, while one current trend advocates for a high fat/ketogenic diet approach. With Carbs under the spotlight, we’re highlighting some of the things to keep in mind when considering a new dietary strategy to achieve your health goals which may involve altering Carbohydrate intake.
Carbohydrates Come out on Top
Carbohydrates act as the predominant fuel source regardless of recommended ratios. The Australian and New Zealand Guidelines recommend the following variables for each macronutrient: (3)
- carbohydrate 45%-65% of energy
- protein 15%-25% of energy
- fat 20%-35% of energy
These variables account for age, level of activity, plant based food intake and other factors, while also recommending limiting saturated fat intake. Carbs are an essential component of any diet and also help to limit intake of animal food sources. Given a bad reputation in recent decades, carbohydrates still need to be recognised for their health giving properties.
The Case FOR Carbohydrates
Carbohydrates are simple sugars occurring either as monosaccharides or chains of connected monosaccharides. The bonds of these chains (such as starch) are either hydrolysed in the small intestine to monosaccharides or are resistant to breakdown (such as dietary fibre). (2) From an evolutionary viewpoint, humans are well adapted to digesting starch. (2) Fibre rich foods are synonymous with being plant based carbohydrate sources which beneficially feed the gut microbiome. (More on this in our recent blog “Fabulous Fibre” HERE).
Carbs have been given a bad rap due to the amount of ultra processed foods (think cookies and cakes) which are high in carbohydrates on two fronts – in the form of both processed grains and refined sugars. It’s really a case of quality vs quantity – as we frequently see that healthy traditional diets are being replaced. Naturally higher carbohydrate dense plant based foods such as legumes, other vegetables, and coarse grains are now lacking in daily diets in many cultures. (2)
Both a higher/excessive intake of poor quality carbohydrates or an overall drastic reduction in this macronutrient can have a negative impact on health. Going too low in carbohydrate intake can ultimately make you go “too slow”. Metabolism and cognitive function readily utilise carbohydrates as a fuel source, with consumption of complex carbohydrates correlating with successful brain ageing and improved memory both in the short-term and long-term. (4)
The timing of ingestion can also influence the outcome of adjusting macronutrient intake. For example, one study found that when the proportion of daily carbohydrate ingested in the morning was high, less total food energy and carbohydrate were ingested over the entire day. (5) In this case, a modest reduction in overall calorie intake was achieved through a high carbohydrate breakfast.
Making your Macronutrients count
Ideally, when consuming a well-balanced diet, allowing for moderate intake of Carbohydrates, as well as Fats, and Protein is the best approach. Making dramatic or sudden changes to macronutrient ratios may not be suitable without professional guidance. Too big a shift in the diet creates the possibility of nutrient deficiencies, calorie deficit or excess and even detrimental changes to gut microbiome due to lack of fibre or excess consumption of animal sources.
Since the jury is still out on the best macronutrient ratio, the take home message is simple – there is no one size fits all approach. Ultimately, getting the best combination of energy dense and nutrient dense foods in the form of whole foods, rich in plants (aka carbs!) is what counts for supporting a healthy and active lifestyle.
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