What was the trigger that convinced you that it was time to get back into shape, lose the extra weight and improve your body composition? For some people it was putting on clothes that are now too small, for others it was the number on the scale.

While this number may have been what motivated you to lose weight in the first place, it shouldn’t be your marker of success. There are different methods for determining if your body composition should be improved. The weight you see on the scale should not be the only marker considered. In this article, I will talk about your weight, BMI, waist circumference and fat percentage. You will also have access to the standards so that you can see what changes you could make to your body composition.

Weight on the scale:

The weight represents the total mass of our body including fat, but also our bones, muscles, water, vital organs, and more. Most people who want to lose weight want to lose fat, not muscle, bone or water.

At the beginning of your weight loss process, you probably had a number in mind that you wanted to reach when you looked at the scales. Unfortunately, the number you’ll get is a reflection of your entire body. You will not get an accurate measurement of your fat loss. You may increase your muscle mass during your weight loss and not see a difference on the scale. However, this does not mean that your body composition is not improving.

Body Mass Index (BMI):

Let’s look at another measure that has been used for many years to measure weight: BMI. Body Mass Index (BMI) is a ratio of a person’s weight, or body mass to height.

Take two individuals weighing the same weight, 180 lbs. One person is 160 cm tall and the other is 190 cm tall. These two individuals will look totally different. Here are the different formulas you would need :

1kg=2,2 lb.

1m= 100 cm

BMI= body weight (kg)/height (m)2.

Thus, for the first individual the calculation of his BMI is as follows:

BMI= (180lbs/2.2lb)kg/(1.60m x 1.60m) = 81.8kg/2.56m2 = 32 kg/m2

For the second individual, it will be

BMI= (180lbs/2.2lb)kg/(1.9m x 1.9m) = 81.8kg/3.61m2 = 22.7 kg/m2

The body composition of these two individuals is therefore likely to be quite different. Now let’s see what these numbers mean. These body mass ratios can be placed on a continuum to assess obesity and health benefits.


Less than 18.5: indicates unhealthy leanness. This can lead to many psychological disorders and physical injuries. An increase in caloric intake may be necessary.

Between 18.5 and 24.9: indicates a body mass within the norm. You can avoid many weight-related illnesses by staying in this category.

Between 25 and 29.9: indicates the overweight category. You are at higher risk of developing weight-related diseases. You could therefore, through diet and physical activity, try to move down one category to get the health benefits of a healthy weight.

Between 30 and 34.9: indicates the obesity category class 1. Your chances of suffering from diseases related to your weight are increased. You could start changing your lifestyle habits in order to reduce your weight and avoid various chronic diseases.

Between 35 and 39.9: this is the category of severe obesity or class 2. No need to tell you that the risk of disease at this stage is high. In recent years, new categories for classifying obesity has appeared for people with a BMI of over 40.


If we look back at our previous example, in which category would our two individuals fall? The first person would be in the obesity category while the second would be in good health. This is how we can tell the difference between two people of the same weight with a BMI.

One problem with the Body Mass Index is that it only takes into account the weight of the person. It, therefore, does not consider what makes up the weight just like the scale. A person with 90 lbs of fat is comparable to someone with 90 lbs of muscle for this model. Thus, a person with a more developed musculature may be in the overweight and obesity categories even though he or she is in very good health.

Waist circumference:

This is where the waist circumference comes into play. Numerous studies based on the waist circumference have been used to target health standards. Thus, we can predict a person’s risk of developing a chronic disease by comparing their BMI to their waist circumference. However, these standards are different for men and women.

For men, a waist circumference (WC) of:

Less than 94 cm is associated with a low risk of weight-related disease.

More than 102 cm is associated with a high risk of weight-related disease.

For women, a waist circumference (WC) of:

Less than 80 cm is associated with a low risk of weight-related disease.

More than 88 cm is associated with a high risk of weight-related disease.

Waist circumference measurement

What happens between 94 cm and 102 cm for men or 80 and 88 cm for women? From 94 cm, the risk of developing weight-related diseases increases to 102 cm. Therefore, as the waist circumference increases, so does the risk. The same principle also applies to women.

A person with a BMI in the obesity category having a waist circumference in the norm would therefore not be considered obese.

This is why you need several measurements to analyze your body composition. Using these, you can compare your different measurements to see which categories you are in.

In addition, many other circumferences can be taken to measure your progress. Hip, thighs, biceps and calf circumference are other measurements that can help you see an overall progression in the different muscle masses.

Fat percentage

Since your primary goal was weight loss and most likely fat loss, there are other tools that can help you measure your progress such as fat percentage. Fat percentage can be measured in a variety of ways such as using an adipometer or a skinfold clip. Using the accumulation of subcutaneous fat, it is possible to calculate the percentage of fat.

Unfortunately, this method also has some limitations, as it does not allow for the calculation of abdominal fat. Another way to measure body composition is using a bio-impedance scale. These scales send an electrical current through the body and allow you to determine different values such as the percentage of fat, the amount of muscle mass, the degree of hydration and several other variables depending on the resistance the body puts up to the current. Although this measure of body composition gives us a lot of information, it also has some limitations.


Many scales do not accurately measure your percentage of fat, but measure certain segments of your body such as your legs or arms and then use equations to estimate your data for the rest of your body. Some more accurate scales, however, can measure each segment of your body separately: arms, legs and abdomen.

This is why you should not compare your results between two different scales, but always use the same instrument to see your improvements. These scales can be a great help in comparing your progress toward your goals. And so the changes measured on the scale during your weight loss process can be considered reliable. For example, if your scale indicates that you have lost 5% fat or gained 5 pounds of muscle mass, you can rely on that result.


To help you analyze your fat percentage, here is a table that contains body composition standards for men and women according to their age. However, it is generally recommended not to have less than 3% body fat for men and 10-13% for women. In general, a man with 10-22% body fat and a woman with 20-32% body fat would be considered healthy.

Men :

Very lean4,2-6,47,3-10,39,5-12,911-14,811,9-16,213,6-15,5
Needs Improvement19,7-23,322,4-25,124,2-26,625,6-28,126,4-28,825,8-28,4

Women :

Very lean11,4-1411,2-13,912,1-15,213,9-16,913,9-17,711,7-16,4
Needs improvement24,2-28,225,8-29,628,4-31,930,8-33,931,5-34,431-34

Based on the fat percentage you get from your scale, you can now compare it to these standards and see which category you fall into.

As you can see, in order to do a good body composition analysis you need to be able to analyze several data to get an overall picture and see if it is improving or not. Therefore, it is recommended that you use different measures such as weight, BMI, waist circumference and percentage of fat to get an overall picture of your body composition and your progress.

Sometimes, good before and after pictures can also help you stay motivated when trying to achieve your goal.

Sandrine Lavoie-Filion, Sandrine Santé Active

  1. Physical Fitness Assessments and Norms for Adults and Law Enforcement. The Cooper Institute, Dallas, Texas, 2009.
  2. American College of Sports Medicine: Guidelines for Exercise Testing and Prescription: Ninth Edition, 2013.