How is weight loss measured?

Ruth Frechman
Nutrition & Dietetics
If you are "scale-phobic," you can access weight loss by how your clothes feel. If you need a belt to keep your pants on, good job! You have definitely lost weight.  

Although there are a number of ways to measure 'weight loss', it is more beneficial to focus on fat loss. Weight loss can simply be measured by getting on a scale. But scales can be deceiving because they can deviate drastically given your level of hydration, sodium levels, whether or not you just ate, etc. A much better way to gauge progress would be to measure fat loss by figuring out your body composition. The most common method to do this is skin fold testing using a set of calipers. This test will give you body fat percentage that you can then use to figure out how much of your weight is fat mass and how much is lean mass. When it comes to weight loss, you want to focus on losing fat mass, not water weight (which will fluctuate daily). Lastly, people tend to become fixated on the numbers on the scale. They become obsessed with every little change. This can cause them to become depressed and unmotivated. Long-term weight loss will result in a net decline of body weight, but rarely does it occur in a linear fashion. So instead, focus the process of losing weight, not just the end result! 

There are many ways to measure weight loss. Some methods only measure weight and not actual fat loss. Both can be important since often individuals who are changing their body composition will be reducing body fat and putting on muscle, but not seeing much difference in the number on the scale. Some methods to measure weight loss and fat loss include a scale, hydrostatic weighing, bioelectrical impedance, skin caliper measurement, and body mass index (BMI). The scale is one of the easiest methods to use to track weight loss, but a scale does not measure overall fitness. It is impossible for the scale to differentiate between muscle and fat. Body fat measurements provide a much better indication of positive results. A weight loss program which incorporates resistance training can often increase muscle mass while reducing body fat. As discussed earlier, the scale can sometimes be discouraging if the pounds do not decrease as fast as one may expect. Hydrostatic weighing is the most scientific and accurate means of obtaining body fat measurement, but it is also difficult to incorporate. During hydrostatic weighing, an individual is submerged into a tank of water and weighed. They are then weighed on dry land and a difference in the measurements is calculated. In the water, fat floats and everything else sinks. So the difference in “dry” weight versus “wet” weight is the pounds of fat one has on their body. Bioelectrical impedance is the process of sending a low-level electrical current through the body. Muscle is composed primarily of water and water is a conductor of electricity. The more water in the body the quicker the current will travel through. Skin caliper measurement involves using a device to measure body fat by pinching the skin at various sites on the body. You can measure the fat on the bicep, tricep, under the shoulder blade, and on the top of the hip and figure the sum of these measurements into an equation to come up with a number in just a few minutes. To increase accuracy, an individual should strive to have the same personal trainer do the measurement each time. Body mass index (BMI) is a measurement taken by calculating a ratio of the individual’s height by their weight. The result of this calculation can show an individual's prevalence towards obesity related diseases. BMI has its limitations; much like a scale, it is impossible for this method to differentiate between muscle and fat.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.