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Thursday, 23 June 2022

What are macronutrients?

When trying to lose weight, it’s common to count calories and macronutrients in food, but does this work for weight loss or is it a big waste of time? Let’s investigate.

Firstly, let’s talk about the difference between the two.

  • Macronutrients (or macros) are the nutrients we need in large amounts.
  • Micronutrients, on the other hand, include vitamins and minerals that are needed in much smaller amounts (although no less important).

Macronutrients can be broken down into three sub-groups that are measured in grams: carbohydrates, fats and protein. All macros are essential and play different roles in the body. For example, our bodies rely mainly on carbohydrates as the preferred source of energy.

Carbohydrates can be further divided into simple and complex carbohydrates, depending on their chemical structure and physiological effect. In short, it’s important to get most of your energy intake from complex carbohydrates. They take longer for your body to digest, keep you fuller for longer, and are packed with fibre which is important for gut health. Think a vegetable stir-fry and rice, porridge, or hummus and wholegrain crackers.

Lipids include fats (solid at room temperature – like butter) and oils (liquid at room temperature – like olive oil). Commonly, the term ‘fats’ are used when referring to both fats and oils. Fats can be an energy source if carbohydrate intake is low, fat insulates against temperature extremes and forms part of cell membrane structures.

Protein provides the body with the amino acid building material for building cell tissue, from hormones and supporting immune function. They can be sourced from both animals and plants. Animal protein contains all the nine essential amino acids and is therefore classed as complete proteins. Plant foods are deficient in one or more of the essential amino acids and are classed as incomplete proteins. It doesn’t mean one is better than the other, just that to obtain the full spectrum of amino acids our bodies require, it’s important to eat a range of foods (and if you’re vegan, getting protein from a diversity of plant sources). Foods high in protein include meats, chicken, fish, milk, eggs, yoghurt, cheese, tofu, tempeh, lentils, nuts and seeds.

The recommended daily intake (RDI) for men is 0.84g/kg body weight and 0.75g/kg body weight for women. However, new research released by the CSIRO supports an increase in protein intake of 1.2-1.6g protein/kg bw, especially for overweight Australians who are seeking to lose weight.

In summary, the National Health and Medical Research Council recommends the following percentage energy balance to reduce chronic disease risk:

  • 40-65% from carbohydrate
  • 20-35% from fat
  • 15-25% from protein

So why do people want to change their macro intake?

The impression is that if you change the macro intake, for example, eat fewer carbs and more fat than recommended (like the keto diet) you’ll lose more weight than by reducing your total energy intake. However, the research doesn’t support this. In fact, numerous studies indicate no significant difference in weight loss between low fat and low carbohydrate diets. Other studies confirm that when people just eat less, weight loss occurs regardless of the macronutrient ratio.

The keto diet requires reducing carbohydrates to just 5-10% of overall intake, which cuts out significant food groups. Research indicates there’s no difference in weight loss between keto and energy-restricted diets (e.g., reducing the amount you eat in total) (O’Neill, 2018).

The macro breakdown of common foods

Most foods contain a mix of all the macronutrients, but the proportions will differ. For example, meat contains mainly fat but also some protein, water and other nutrients.

The macronutrient distribution of selected foods:

Food (per 100g)

C – Carbohydrates | F – Fat | P – Protein

  • Almonds: 16% C | 50% F | 20% P
  • Avocado: 8% C | 13% F | 1.6% P
  • Banana: 21% C | 0.3% F | 1.6% P
  • Beef (65g cooked): 0% C | 36% F | 10% P
  • Oats: 10% C | 2% F | 2% P
  • Watermelon: 8% C | 0% F | 0.6% P
  • Yoghurt (plain): 5% C | 3% F | 5% P

*Australian Food Composition Database.

Note: The remaining % of the food composition includes water and other nutritional components. Fruits and veggies typically have high water content.

How do you count macros?

Macros must be listed on food labels according to the Food Standards Code. So, you’ll see the values on the nutrient info panel on any packaged food. There are plenty of apps like myfitnesspal that help with counting macros and calories, and draw information from both government databases and user-generated data. You’d tally up all the macronutrients in the foods you eat in a day and then compare them to the ratios set.

Do you need to count macronutrients for weight loss?

No – counting macros and calories can be inaccurate for the following reasons:

  1. Calorie counts on labels and databases are averages, so the true calorie count of what you’re eating may be higher or lower.
  2. Not all of the calories (or macros) are absorbed. For example, only 85 percent of the kilojoules in almonds is actually absorbed by the body, the rest of the fat in almonds is bound up in fibre and passes straight through.
  3. Cooking increases the number of calories absorbed, and labels may not reflect this.
  4. Typically, we’re not good at estimating how much we eat. For example, was that one tablespoon of peanut butter or a heaped tablespoon?
  5. Everyone absorbs different amounts of macros and calories from foods according to their individual gut microbiome composition. The values on the labels and in the apps may not reflect the exact amount of energy you’ll get from the foods eaten.

If we eat a whole variety of foods from the five food groups, we’ll get sufficient amounts of each of the macronutrients without needing to count anything.

Counting calories can be an interesting exercise if you’re curious about whether you’re close to your energy requirements or way over.

Obsessing over numbers can result in losing touch with intuitive eating. It’s best to treat our food as a whole, rather than breaking it down into nutritional components. Plus, how do you even count the macros for that pizza you shared with your mates?

All in all, calorie counting can be imprecise, stressful, and is rarely necessary. The truth is that most people won’t count calories for more than a few weeks. Why? Because it’s boring, inaccurate, and let’s be honest – there are other things to be doing with our time than counting and tracking calories.

The message for the general population is increasingly clear – rather than fiddling around with macronutrient distribution in an aim to avoid weight gain, it’s more productive to focus on the overconsumption of energy-rich junk foods and soft drinks outside the food groups recommended in the Australian Dietary Guidelines (as well as moving more).

References

Food Standards Australia New Zealand (2019) Australian Food Composition Database

Gardner, C. et al (2018). Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight

Adults and the Association With Genotype Pattern or Insulin Secretion. JAMA, 319(7), 667. https://doi.org/10.1001/jama.2018.0245

Ketogenic diet, Fad or Future. Professional Development Seminar, Matt O’Neill APD.

NHMRC. (2006). Nutrient Reference Values | for Australia and New Zealand. Retrieved from https://www.nrv.gov.au/

Noakes, M. (2018). Protein Balance: New concepts for Protein in Weight Management.

Sacks, FM, et al 2009, ‘Comparison of Weight-Loss Diets with Different Compositions of Fat, Protein, and Carbohydrates’, New England Journal of Medicine, vol. 360, Massachusetts Medical Society, no. 9, pp. 859–873, <http://www.nejm.org/doi/10.1056/NEJMoa0804748>.

Tomiyama, A. J., Mann, T., Vinas, D., Hunger, J. M., Dejager, J., & Taylor, S. E. (2010). Low calorie dieting increases cortisol. Psychosomatic Medicine, 72(4), 357–364. https://doi.org/10.1097/PSY.0b013e3181d9523c

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