Fat Loss vs. Weight Loss: What’s the Difference?

Although the terms are often used interchangeably, fat loss and weight loss are not the same things. Weight loss refers to a decrease in your overall body weight from muscle, bone, water, and fat, while fat loss refers to weight loss strictly from fat. Here’s a detailed breakdown of the difference between fat loss vs. weight loss.

What’s the difference between fat loss vs. weight loss?

An individual’s weight is a measurement of their gravitational pull. This measurement accounts for fat-free body mass (bone, organs, muscle, water) and fat mass (essential and non-essential). (1) Weight loss is a reduction in total body mass from all of these factors, meaning, a reduction in weight can be influenced by a loss of bone mass, muscle mass, fat mass, and/or water. And the opposite is true for weight gain.

Fat mass is specific to the amount of fat on a person’s frame, which is a component of weight. Fat loss is a reduction in body fat, which contributes to weight loss. However, given there are multiple factors that influence weight, a loss of fat does not guarantee that a decrease in weight will be immediately reflected on the scale.

Since the components of weight are in a constant state of flux, namely water, glycogen, and gastrointestinal contents, an individual can experience fat loss without seeing a noticeable change in weight as the other components may have increased while fat was decreasing. Changes in fat (loss or gain) will influence weight (loss or gain), while changes in weight (loss or gain), especially day-to-day, are not necessarily influenced by fat. For example, you can create weight loss by dehydrating yourself or passing a bowel movement, but you haven’t lost any fat. You can also increase weight by drinking more water or eating a meal, but you haven’t necessarily gained any fat.

Weight can easily be influenced and manipulated by changes in water, salt, and carbohydrate intake. Not only will drinking more water increase weight alone but salt and carbohydrates cause the body to retain more water; for each gram of carbohydrate stored in the body as glycogen, the body also stores three grams of water. (2) Therefore, increased consumption of water, salt and carbohydrates will cause weight to increase, while a decreased consumption of water, salt, and carbohydrates will cause weight to decrease, however, neither scenario is necessarily a representation of changes in fat mass. Not to mention, a women’s menstrual cycle can cause weight fluctuations for a variety of different reasons, none of which are necessarily a representation of changes in body fat. (3)

It is completely normal to see small fluctuations in weight from one day to the next, however, it is important to understand that these are not a direct reflection of increases in fat tissue. In fact, studies have shown that short chronic periods of overfeeding can contribute to weight gain, however, only a small portion of the increase in weight is related to actual increases in body fat or changes in body composition, especially when protein intake is controlled for. (4)(5)

Why You Should Focus on Fat Loss and Not Weight loss

Although weight loss is often used as a health goal, what most people are actually looking for is fat loss or changes in body composition. Body composition describes the amount of fat mass and fat-free mass (organs, bones, water, and muscle) in the body. It’s important to note that there are different types of fat in the body; essential and non-essential body fat. Essential fat is fat that our body needs to perform essential functions, protect our organs, store energy, and support our hormones. Non-essential fat is any fat above the essential range, which is excess stored energy, and the form of fat targeted for a goal of fat loss. A women’s essential fat range is naturally greater than a male’s due to deposits in breasts, uterus, and sex-specific sites. (6)

Generally speaking, changes in body composition and fat loss are more healthful goals than weight loss alone, and increasing overall muscle mass is arguably the best way to support this. (7) Although both one pound of muscle and one pound of fat weigh the same, muscle tissue is much denser than fat tissue and, therefore, takes up less physical space. Increasing muscle mass, while decreasing fat mass, will cause changes in body composition by reducing inches in measurement on a person’s frame, and, in some cases, weight may even remain the same. For example, if an individual loses 5 pounds of fat but gains 5 pounds of muscle, the number on the scale will remain the same but their body composition and body shape will look completely different.

With that said, a person’s weight will arguably decrease over time as fat loss progresses, however, you are looking for trends that happen over weeks and months, not what happens from one day to the next. It is completely natural to see several pound weight fluctuations from one day to the next – these are not a representation of fat gain or loss. (8)

A graphic representation of fat loss vs. weight loss.

How to Tell if You’re Losing Fat

Unfortunately, most scales don’t differentiate weight loss from fat loss and most people don’t have the machinery required to test body fat levels at home. Fortunately, you can use the scale in conjunction with other metrics to help identify trends to determine whether or not you are losing body fat.

Body measurements are a great way to monitor and track changes in body composition, fat loss, and muscle gain. Taking the time to measure the circumference of your hips, chest/bust, waist, arms, and thighs can help you monitor changes in body size, which is a great way of analyzing fat loss. Along with measurements, visual assessments in the form of pictures can help you review progress and identify changes in body shape. By taking photos of yourself at regular increments in your journey you can create a visual representation of changes in body composition and fat loss.

Nevertheless, if you are going to use the scale as a metric, it is imperative that you weigh yourself regularly, ideally daily or at least several times per week, to ensure that you have multiple data points. The less frequently you weigh yourself the fewer data points you have and, therefore, the less data you have to interpret whether changes in weight are changes in fat loss or simply day to day weight fluctuations. The more often you weigh yourself the more data points you will have and the easier it will be to identify trends and ignore natural weight fluctuations.

Alternatively, if you are interested in more accurate body fat measurements, you can look for caliper testing, hydrostatic weighing, DEXA scan, and bioelectrical impedance analysis (BIA) testing. Many of which are easily found at local gyms or health clubs.

Ways to Assess Progress Beyond the Scale

With all of this being said, please keep in mind that weight loss and fat loss are only two of the many, many ways you can measure progress and improve your health. If fat loss happens to be your goal, that’s fine, but be mindful of all of the other positive changes, such as increased energy, increased vitality, improved confidence, reduced cravings, increased strength, better sleep or improved performance, that you may be experiencing instead of remaining solely focused on the scale, measurements, and body composition.

The Bottom Line

Although the terms are used interchangeably, weight loss and fat loss are different. Weight loss refers to a total reduction in body mass, while fat loss refers to a reduction in weight specifically from fat mass, which contributes to weight loss. Generally speaking, fat loss is a more healthful goal than weight loss and can be measured through body measurements and/or specific body fat testing and scans. Fat loss is best supported through of combination of diet and resistance training.