Weighing Up Exercise

Wednesday, 19 December 2018

Exercise has been likened to medicine, that if taken in the right dose, it can help not only prolong life, but make it a quality one. From heart health, to mental health, gut health to joint health, exercise has the ability to improve nearly everything! Exercise can help with managing blood glucose levels and can even reduce the risk of some cancers. Evidence backed up by the Oncology Association of Australia suggests that exercise during cancer treatment leads to better health outcomes, with the best results seen in those who were able to exercise on treatment days!

Ok so exercise really is what it’s cracked up to be – but what about weight?

Weight loss is a very common goal when it comes to exercise. We know that exercise contributes to weight loss or helps with weight management. However it is a well known fact that the biggest impact of weight loss comes from a combined approach with food. So is weight the best measure of success from exercise? What about all the other benefits you get?

Well the first issue lies in the tool of measurement. The scales that define our success are so variable. For consistency reasons, this measurement needs to be taken first thing before breakfast. Secondly, all it tells you is a number – what is that number made up of?

Well, it’s made up of our fat free mass:

  • Bones
  • Muscles
  • Water
  • Tissues

It’s also made up of our fat mass:

  • Subcutaneous fat which lies beneath skin
  • Visceral fat that accumulates around organs

Fat mass can pose a risk on our health and stop our body functioning properly. Visceral fat is often called ‘high risk’ fat as it can affect metabolic processes and lead to insulin resistance. The key to good health is to reduce both types of fat!

Therefore Body Mass Index (BMI) which is calculated from weight and height does not show the complete picture. The current issue is that while there are other means of measurement, they are not widely available due to costs. Visceral fat reductions can only directly be seen from a CT scan, however it will indirectly be shown with improvements in blood test results.  Overall body fat reductions can be shown from DEXA scans, InBody scans, as well as skin calliper tests. There are some scales (Bioelectrical Impedance Analysis) that can measure this, however they are the least accurate. These scales can be unreliable as hydration, previous exercise temperature, recent food intake and time of day can all impact the measurement. Ideally these are used in controlled conditions e.g. same time of day, not after strenuous activity, hydrated. For those seeking a more cost effective solution, grab a tape measure and measure your waist. You can either pick the belly button as your point of measurement or take the middle between the bottom rib bone and top of the hip bone.  Waist circumference has less variability than weight! The recommendations for health are for women to be under 80cm and men to be under 94cm (these may be lower depending on your ethnicity).

The good news is that exercise, particularly aerobic exercise, is effective in achieving both subcutaneous and visceral fat loss. While available evidence is still variable, moderate to high intensity aerobic exercise indicates a greater effect.

Ultimately if your goal is weight loss, start using the term ’fat loss’ and this will help create more positive outcome focused on body composition, rather than just a number. Ditch the scales and measure your waist!

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