Measurement of body fat gives you a more accurate picture of your body health than only measuring your body weight. Whenever you are targeting weight loss you should essentially only target body fat loss. In order to do so it is wise to know where you are starting from and where you want to end up.
Your body shape and tone is determined by the body fat you carry and your muscle mass. To give you an example, in the image below, both have a body fat level of 6-8% but the difference in their physique is that the person on the left has more muscle mass:
Example of how physiques vary based on different body fat levels:
(Images for reference only)
Body fat can be measured using x-ray absorptiometry, bodpods (use air displacement; other technology uses water displacement, etc), callipers or digital body fat weighing machines.
X-Rays Absorptiometry or Bodpod method have the least error in accuracy but neither is it readily available nor is it cheap (over $50-100 per measurement!).
Callipers: I have used callipers a couple of times in the past and personally found it to be intrusive. In this method, folds of skin /fat are pinched off from various points on your body and held between the callipers to estimate how much body fat you have. Various readings on the calliper are entered in a formula to calculate the final body fat percentage. A lot of professional body builders and other serious athletes rely on this method because of its accuracy.
Digital body fat measuring machines are more expensive than the callipers but are also the most convenient. You must have seen these around your local gyms where they are used extensively (atleast in India).
How these machines work is you enter your height and age into the machine and step on the plate. The plate sends a tiny electric current (don’t worry you won’t even feel a tickle) through your body and based on the differing impedance it receives, it estimates your body fat, muscle mass, visceral fat, etc. It also tells your weight (read the devices features to know all the information it can provide you as some only measure body fat).
The main problem with the digital body fat measuring devices is that they can be inaccurate depending on your hydration levels. The best way to use them is to measure at the same time of day preferably in the morning before you have your breakfast. If you have had alcohol the night before it is best to wait for the next day when your hydration levels out. Although even after you do all this, the readings might be all over the place which is why you have to choose your manufacturer very carefully.
I trust the Omron brand and highly recommend it. My brother owns a fitness centre and has been using it for the last 4 years and also whoever I have recommended it to has had no complaints so far. The model that I use is Omron HBF-212 Body Fat Analyzer
and I bought it sometime last year from Amazon:
It can accept and store 3 people’s profile so that you don’t have to enter your age and height every time you use it. It has a guest profile also which you can use for people who will not use the machine frequently (you have to enter age, height, etc for the guest profile before every reading).
The measurements it provides is: Weight, Body Fat percentage, Visceral Fat percentage, Skeletal Muscle percentage, Body Age, Resting Metabolic Rate and Body Mass Index (BMI). This is more than the information you need to track your progress. I have received consistent readings over the last few months and highly recommend it to track your weight loss (no, fat loss!) journey.