Fat Loss vs Weight Loss

Body fat measurements and the measuring tape are recognised as  superior methods for measuring “weight loss”.  When one declares that they want to “lose weight”, what they often mean is that they want to “lose fat”.

Getting your body fat percentage measured, and seeing what the number really means is important for your goals.

Body fat percentage is simply the percentage of fat your body contains.  If you are 75Kg and 10% fat, it  means that your body consists of 7,5Kg fat and 67,5Kg lean body mass (bone, muscle, organ tissue, blood and everything else).

A certain amount of fat is essential to bodily functions.  Fat regulates body temperature, cushions and insulates organs and tissues and is the main form of the body’s energy storage.

Body Fat % Categories


Essential fat 10-12%
Athletes 14-20%
Fitness 21-24%
Average 25-31%
Obese 32%+


Essential Fat 2-4%
Athletes 6-13%
Fitness 14-17%
Average 18-25%
Obese 25%+

Knowing your body fat percentage can also help you determine if your weight loss goals are realistic.  Remember, weight loss doesn’t always mean fat loss.


Let’s say you’re a 60Kg woman with 23% body fat, and you goal is to “lose 10Kg”:

Initial body fat: 60kg x 0.23 fat = 13,8Kg body fat

Lean body mass: 60Kg total – 13,8 fat = 46,2Kg lean body mass (bones, organs and all else)

Goal: 60Kg – 10Kg = 50Kg

As you can see, the goal of losing 10Kg is not realistic or healthy.   At 50Kg this woman still requires 46,2Kg of lean body mass (bones, organs, etc.), but would only be carrying 3,8Kg, or only 7,6%  body fat.   From the chart above, you can see that this is a dangerously low percentage, below the essential fat.

A better goal might be for the woman to reduce her body fat from 23% to 18%.  In this case:

60Kg (current weight) x 0.18(target body fat%)= 10,8Kg (target body fat weight)

46,2Kg lean body mass + 10,8Kg (target body fat weight) = 57Kg goal weight

So, for this individual to achieve a lean, but healthy 18% fat, she would need to lose only 3Kg of fat, reducing her weight from her current 60Kg  to 57Kg. 

Losing more than 6kg may mean losing lean body mass (usually  metabolically-active muscle tissue), which is clearly not desirable.

So before you decide that you need to “lose weight”, remember to consider that “weight” consists of both lean body mass and body fat.   Try to keep your weight loss goals realistic, and remember, keep the calorie-burning muscle, and lose only the fat.

On many occasions one will gain muscle during the exercise programme and that will also tip the scales a bit. The best thing is to keep track of the body composition in a 4-6 week interval

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