Weight Loss vs. Fat Loss: Is The Weight You're Losing Really Coming From Fat?

Wednesday, September 27, 2006 - 7:21am

By Michele Silence, MA

Measuring weight loss is essential in determining if the weight you’re losing is really coming from fat. High levels of body fat are closely tied to many of the diseases affecting people today. And, size is not always the best measure. A large athlete weighs much more than the average person and throws off various tests dependent upon weight. On the other hand, it’s possible to drop weight without affecting fat stores very much. The result is sagging skin, no muscle tone, and a level of body fat that leads to a number of health risks. What the body looks like on the outside can be very misleading when looking at muscle to fat ratios. Compare these five common assessment tools to see what they do (and do not) tell you about what’s happening inside your body.

1.   What do weighing scales tell you?

Step on. Step off. Step on again. The scale usually displays a number you don’t want to see. A scale can only tell you how much you weigh in total, but it never gives you any indication if the weight you’ve gained or lost is from water, muscle, or fat. The scale is good as a warning sign, giving you a heads-up when you’re gradually gaining weight before things get out of control. But, if you’re interested in seeing how much fat you’re really losing, avoid the scale. Or, use weighing scales only occasionally.

2.   What does the Body Mass Index (BMI) tell you?

Body Mass Index is an expression of height-to-weight and closely relates to body fatness. High BMI numbers are linked to hypertension, high blood cholesterol and heart disease. Use the following formula to convert your height and weight into meters and kilograms, and then calculate your BMI:

  • Height in inches x 2.54 divided by 100 and squared (multiply number by itself)
  • Weight in lbs. divided by 2.2
  • Weight (determined above) divided by height (determined above)

Or, simply use the Body Mass Index Calculator provided by The Diet Channel.

A desirable range is 20-25.

  • 25-29 is considered obese.
  • 30-40 severely obese.
  • 40 is morbidly obese.

3.   What is the waist-to-hip ratio (WHR) and what does it mean?

Waist to hip ratio is a way to look at regional fat distribution to see whether or not you’re more prone to heart disease and diabetes. Apple shaped individuals store fat in their abdominal region whereas pear shaped people store more fat in the thighs and hips. WHR’s above .95 for men and over .85 for women suggest an increase risk for heart disease.

As you get in better shape, your WHR will go down. Find out your WHR by using the following formula:

  • Measure against the skin or with minimal clothing
  • Use the most narrow part of the waist and the largest circumference for the hips
  • Keep the measuring tape taut, but do not stretch it

4.  Taking your measurements to record weight loss

Using a tape measure you can record the circumference of different areas of the body. This allows you to see at an instant when you’re losing weight, gaining, or staying the same. Tape measurements are good when you’re just starting out because you’ll see a definite improvement within the first six weeks. Clothes will fit better and you’ll see the numbers gradually get smaller and smaller.

Over time though, measurements will not tell you what changes are happening internally. Someone who is a size 12 can remain a size 12 while totally boosting the amount of muscle inside their body so that they actually weigh more on the scale. Another person who is also a size 12 can do no strength training, remain at the same weight, and be quite over fat in terms of how much fat is inside. Looking at measurements alone can be very misleading, especially if you’re concerned about health risks.

It’s also possible to estimate body fat by measuring the upper arm, wrist, and hip. Measurements are then recorded and inserted into a formula to estimate body fat percentage. For those who are over- or under-weight, this method is usually not very reliable.

5.   Body fat testing

Body fat testing helps you see what percentage of fat your body is carrying in comparison to muscle and water (including all the blood, intracellular fluids, and other moisture components). The lower the body fat, the more muscular your body will appear. For men, body fat levels should read from 12-20%. For women, 18-25%.

Body fat can be tested in a number of ways. One technique is by underwater weighing. The premise is that fat displaces water at a different rate than muscle. To do this test, you are dunked under water, you release air from your lungs, and then your body is weighed instantly. The amount of buoyancy corresponds to how much fat your body is holding.

Skinfold calipers use a “pinch” of skin to measure how much fat is on three different areas of the body. The numbers are added together and used to calculate an average percentage of body fat. Be sure to have someone skilled in this technique do the test though, accuracy of this measure is highly dependent on it.

Bioelectrical impedance sends a weak electrical current (you don’t feel it at all) through your body. Fat and muscle resist this current at different rates. The result is a body fat percentage number that shows how many pounds of your current body weight is muscle, and how much is fat. This is the number you want to focus on and watch. If your fitness and nutrition program is working, body fat should decrease and muscle mass increase. These changes may or may not change along with the actual size of your body, especially if you are not very heavy.


Which method is best for measuring weight loss and fat loss?

For best results and to know what’s really happening with your body inside and out, use several of the above measures. Health is more important than size. Aim for lower body fat levels and a more even distribution of body weight. The best way to achieve both is through a balanced aerobic exercise and resistance training program.