Episode 20 – Tracking Changes in Body Composition

Key Topics Covered

The benefits and limitations of utilising different measurement tools to assess body composition changes. Tools included:

  • Bodyweight scales
  • Waist circumference
  • DEXA scans, BodyPod and Under water weighing
  • Skin folds
  • BIA machines/ scales

Tracking Changes with Bodyweight

Easily accessible and an affordable way to measure. Useful for those to measure if weight change is a goal.

Things to be mindful of:

  • Daily fluctuations – change depending on the quantity of food intake, carbohydrate intake, salt intake, fluids, etc.
  • Mindset – Weight fluctuations occur, try not to lose motivation when this happens (especially when weighing yourself often). Eg. If you buy an investment property you don’t see the price fluctuations, they may go up by $1000 then down the next. But if you buy stocks, you see this fluctuation. Overall, it doesn’t matter until you sell it.
  • Underlying work – The calorie deficit! If you average a 500-1000 calorie deficit/day, you should average between 0.5kg-1kg weight loss/week. Your weight can still fluctuate based on the above factors, so it’s a matter of trusting that process.


  • Measure your weight daily, at the same time each day, then average out for the week. This can be useful when doing a slow bulk, this consistently measures the success of that bulk.
  • Or less frequently (once per month).
  • A useful app to measure this is the Happy Scales app. It shows your fluctuations and overall trend.

Waist Circumference

Very easily accessible way of measuring change.

Things to be mindful of:

  • If you’re bulking and waist circumference is increasing significantly, you are likely gaining body fat body fat.
  • If you’re trying to lose weight and the scales aren’t moving, but your waist circumference and reducing significantly, you’re probably gaining muscle and losing fat.
  • Females waist circumference is likely to increase around/during their menstrual cycle. Therefore, fluctuations can occur and using averages can be useful to overcome these.

DEXA Scans, BodPod and Under Water Weighing

Gold standard: DEXA Scan – Measures body fat, muscle mass and bone mineral density. This tool can be utilised every 3, 6 or 12 months to see overall changes in body composition.

The DEXA scan is especially useful to track the progress/ effectiveness of a bulking phase. It will allow athletes and coaches to see how much fat and muscle they have gained during a certain period of time. This information is beneficial to inform how future bulks/cuts may take place. Ie. A slowed bulk to gain more muscle and less fat.


Skinfolds are one of the most accurate ways to measure fat mass with a good practitioner. They are a much more affordable and accessible option, which allows them to be done more frequently.

  • Fluid shifts in the body minimally affect the accuracy of the measure.
  • However, it’s not as accurate when trying to calculate body fat percentage. The formulas practitioners try to use often under-represent body fat percentage.
  • Skin folds become less accurate with individuals who have a large amount of fat, as it’s more difficult for the caliper to grab.

For a practitioner to be good at skin folds, they must consistently be within 2% of their own measure and 10% of the gold standard. This is hard to do. If you’re measuring fat by skin folds always use the same practitioner, different practitioners will measure differently.

BIA Machines/Scales

It’s a scale with handles that sends an electrical current through the body to read body composition. These are very inaccurate. They have not been validated to show an accurate representation of body composition nor tracking changes over time. For the most accurate reading, individuals must have the same preparation prior to each scan, including:

  • Room temperature
  • Time of day
  • Hydration status
  • Food intake
  • Menstruation cycle
  • The machine itself

This is not very realistic to do on a frequent basis.

  • The scale appears to measure fluid, where individuals who are more hydrated show a higher amount of lean mass and thus a lower body fat percentage.
  • We’ve seen fluctuations anywhere between 5-20% body changes over the course of a week. This can be upsetting and confusing to many clients.

Relevant Links/ Resources

Studies mentioned

Successful, substantial long-term weight-loss maintenance

Useful Resources

Happy Scales application

Blog Posts

3 things to focus on to help you lose weight and maintain that loss