Your guide to portion size to help manage weight

23 October 2020 Sophie Scott
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It seems most people now know what foods are good for health, but why are they still not achieving their weight loss goals? Knowing your portion sizes and how to portion control is the key.

What is portion size?

There are three main factors that influence portion size and I’m going to share with you seven strategies to help control portion sizes.

Right now, most Australians are overweight or obese. Why? It’s a complex problem, but continual access to ultra-processed food, less physical activity and increased portion sizes are contributing factors.

Even if people are eating healthy food, by overdoing the portion sizes, they won’t reduce weight. Continually overloading the body with too much food means the body is unable to function at its best. That’s where portion control comes in.

Portion control is important as it allows you to consume the right amount of food that your body requires without overindulging and consuming unnecessary kilojoules.

Portion size and serving size are two terms that are often mixed up.

Serving size is used in two different ways. The first is recommended serving sizes as listed within the Australian Dietary Guidelines. For example, a serving size of broccoli is half a cup. The average Australian needs five to six servings of vegetables like this per day. A serve of oats is half a cup and the recommendations are four to six serves from the grains and cereals group per day.

The other way serving size is used is on food labels. In Australia, serving sizes are determined by the manufacturer, which makes it tricky for us when shopping, because serving sizes are often inconsistent between comparable products or even within the same brand. One cereal has 40 grams as a serve, another 50 grams. Food companies do have to list all the nutrients and energy content per 100 grams as well as per serving size, so the 100 grams column is the one we should be using to compare products. Studies indicate people serve themselves much more than the recommended size on the packet.

Portion size is different to serving size. It is the amount you actually eat. So, one portion of cereal may in fact be two to three servings.

Portion sizes are increasing – both in the home, and when eating out and it’s obvious that larger sizes results in more kilojoules. When people are presented with larger portion sizes, people will eat more, not just stop when full.

The three main factors that influence how much food is eaten, or portion size are:

The actual amount of food presented

The amount of food presented or served has a big impact on the portions people eat. Not surprisingly, studies show that people eat more when they are confronted with larger portion sizes. In the US in the 1950s, McDonald’s offered just one size of soft drink, 210ml, which is just under a cup. Now, there are options of up to 950ml, which is nearly a litre of soft drink, adding up to about 25 teaspoons of sugar. This is well over the World Health Organisation’s recommendation of a maximum of 6-12 teaspoons per day. French fries and hamburgers are now two to five times larger than those originally served. Some restaurants serve up a main meal that is really a meal for two, rather than one.

Plate and glass size

In the home, the sizes of our bowls and glasses have steadily increased, and the surface area of the average dinner plate has increased 36% since 1960.

One study showed that by increasing the size of the dinner plate from a 25 to 30 centimetre plate, people ate 22 percent more food. People pour into short wide glasses, than tall narrow glasses. Also, larger utensils mean people eat more – try eating cereal and meals with a teaspoon.


Larger packages encourage more eating. Often larger packages contain more than one serving, which makes it really hard for people to follow the recommended servings. For example, a large bag of chips may contain 7-12 serves of chips, but most people don’t stop at one serve, they’ll eat the whole bag.

Unlike other animals, if humans overeat one day, they don’t adjust the next, which leads to a continual pattern of overeating.

My top seven strategies to help control portion sizes

  1. Eat from smaller plates and bowls and use small spoons for serving and eating. Try using a dinner plate which is the span of your hand.
  2. Make your home a “portion-friendly zone”.

Pre-portion foods. Don’t eat directly from a box, bag or container that contains multiple servings of a food such as a family size bag of chips or a tub of ice cream. It’s hard to keep track of how much you’re eating, making it easy to overeat. Put the amount of food you want into a small bowl. Seal up the bag or close the lid and put it away.

  1. Serve portions on individual plates in the kitchen, instead of putting all the serving dishes with massive amounts of food on the dining table. This means that it’s less likely for people to go for seconds.
  2. When eating out, share a main meal and entrée with your companion, rather than two main meals – that way you get to taste two different meals and will be eating less that a whole main meal. Under, rather than over order.
  3. Choose the smallest container or cup on offer when ordering takeaway because they usually contain more than enough food and are high in kilojoules.
  4. Don’t be tempted by value meals or supersized/king-sized portions. They may be good value for money, but they will have more kilojoules.
  5. Wait 20 minutes until serving more food. It takes 20 minutes for the stomach to tell the brain it’s full. Chances are, after 20 minutes, you’ll feel full and less likely to go for seconds.


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National Heart, Lung and Blood Institute (2015) Portion Distortion Available at

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Young, L  and Nestle, M, (2002) The Contribution of Expanding Portion Sizes to the US Obesity Epidemic  Am J Public Health. February; 92(2): 246–249.

Sophie Scott

Senior Trainer/Assessor – Nutrition and Dietetics

Sophie is passionate about nutrition, fitness and behaviour change coaching. As a Registered Nutritionist, Sophie takes a wholistic approach to nutrition, focusing on people’s relationship with food, driving a shift to a healthier approach to eating.

Sophie has worked as Personal Trainer and Group Ex Instructor for many years. She has taught a range of group fitness classes from yoga and pilates to Zumba™ and bootcamp. She started teaching at a gym in Vanuatu, then moved to Wellington, New Zealand to launch her own business, fitandfed, focusing on women’s health and fitness, before moving back home to Australia.

Now the Head Trainer - Nutrition at FIAFitnation, Sophie inspires the next wave of fitness professionals and nutrition coaches.

She has extensive experience in the education field, initially working in the area of environmental education, assisting people green up their lives, before moving into the health and fitness industry. Sophie has also presented and written scripts for a number of media outlets including the Eco Reno series on Channel 7’s Sunrise program.

Career in Fitness


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