There is an important distinction between weight loss and fat loss.
While scale weight is one important measure of progress, it can only tell us how much we have lost, not where we have lost this weight from.
Weight loss means losing not just fat, but also water, glycogen and muscle tissue too – whereas fat loss is just that losing fat (while retaining all-important lean muscle tissue.)
When losing weight, if we don’t ensure we are resistance training (which signals to the body to preserve muscle tissue) and eating adequate protein, then we risk losing muscle.
So why do we want to focus purely on fat loss and preserving muscle tissue?
The answer lies in what is referred to as ‘lean body mass’, which is everything in your body that is not fat (muscle, organs, connective tissues, bones, etc).
There are several important reasons why we want to retain as much lean body mass as possible, especially during a diet:

  • Fewer metabolic adaptations as a result of dieting, e.g., reduced number of calories burned at rest.
  • Improved insulin sensitivity (which can positively impact disease states such as type II diabetes, polycystic ovary syndrome, etc).
  • Reduced systemic inflammation. We are increasingly discovering the role of systemic inflammation in many disease states and comorbidities.
  • Improved body aesthetic – think “toned” rather than “skinny fat”.
  • Improved strength and proprioception, reducing the risk of conditions such as sarcopenia and osteoporosis in later life.

When we focus on fat loss, rather than pure weight loss, we use tools to maintain and increase lean body mass, while decreasing body fat levels.