Fat Loss VS. Weight Loss: Dietitian Explains

If you’ve been fixated on the number on your scale, it’s time to shift your perspective and truly understand what that number signifies.

Fat loss refers to the reduction in adipose tissue (fat tissue). On the other hand, weight loss is a broader term encompassing the reduction of overall body weight. This includes body fat, bone and muscle mass, water weight, and even glycogen stores.

Stay with us as we delve deeper into these concepts and guide us toward a more informed and effective fitness regimen.

What is the difference between fat loss and weight loss?

When we talk about fat loss, we’re specifically referring to reducing adipose tissue or the fat in your body. This is the surplus of calories stored in our bodies, serving as a reserve of energy that our body uses in times of need. 

On the contrary, weight loss is a broader term encompassing the reduction of various components in your body, not limited to fat loss alone. Weight loss could also involve the loss of muscle and bone mass, a decrease in water weight, and even the reduction of glycogen stores. 

This is why your body weight tends to fluctuate throughout the day, being at its lightest in the morning and heavier later in the day due to food intake, hydration, and physical activity.

Understanding this key difference is fundamental in setting realistic fitness goals, measuring progress accurately, and maintaining a strong metabolism. 

What is body composition?

According to the Medical Dictionary for the Health Professions and Nursing, body composition is defined as: 

An estimate of the proportions of major components of a living body, as water, nitrogen, sodium; more specifically, the proportion of lean body mass to fat.

A straightforward method of assessing body composition is to consider your overall lean mass, which encompasses the weight of all your bodily tissues except for fat.

Fat loss

Body fat stores excess energy or calories as adipose tissue for later use. However, excessive fat accumulation can lead to weight gain and negatively affect our health.

To address this issue, modifying our diet and physical activity is crucial. By reducing daily calorie intake, you create a calorie deficit. This means consuming fewer calories than you burn, prompting your body to use fat stores for energy and resulting in visible changes in body composition.

Besides adjusting your diet, increasing physical activity, specifically through resistance training, can greatly aid fat loss. Resistance training not only boosts your energy expenditure but also promotes muscle growth. This is particularly advantageous as muscle burns more calories than fat, helping establish and sustain a calorie deficit.

Understanding and focusing on fat loss, rather than just weight loss, allows for a more targeted and effective approach to achieving your body composition goals.

Weight loss 

By reducing food intake and increasing energy expenditure through exercise and activity (creating a caloric deficit), your body is compelled to compensate for the energy shortfall by breaking down body tissues, such as body fat and muscle. This combination effectively promotes weight loss.

When reducing your caloric intake, it is crucial to find the right balance. You want to avoid a severe calorie deficit as it may lead to excessive loss of lean mass, which can significantly impact your metabolism. Therefore, finding the minimum effective dose that allows for weight loss while preserving muscle mass and maintaining a healthy metabolism is important.

Should you focus on fat loss or weight loss? 

Weight loss is often the primary health goal for many individuals. As obesity rates continue to soar, it’s understandable why so many people prioritize shedding pounds. However, despite its prevalence, numerous individuals face challenges in achieving and maintaining weight loss success.

The obsession with weight loss has led many to follow fad diets and extreme workouts, resulting in weight loss. However, this can include losing metabolically demanding tissue like muscle. After significant weight loss, individuals may experience a slower metabolism.

The missing link lies in prioritizing fat loss and enhancing body composition. Rather than fixating on weight loss, which can potentially compromise lean body mass and muscle, leading to a sluggish metabolism, focusing on fat loss encourages mindfulness of your lean body tissue and its impact on nutrition and exercise.

What are the benefits of fat loss?

Weight loss benefits stem from improving one’s nutrition and physical activity. The benefits can have a massive impact on one’s health and include: 

  • Improved blood sugar regulation
  • Improved self-image 
  • Improved lipids (LDL, HDL, Cholesterol) 
  • Decreased risk of developing heart disease, diabetes, and cognitive decline in the future.

Losing fat offers numerous health benefits, particularly regarding weight management. By prioritizing fat loss, you can preserve lean body mass and muscle, allowing you to enjoy the advantages of weight loss without experiencing a subsequent metabolic decline. This approach not only enhances your overall health but also ensures sustainable results.

How to measure your fat loss progress.

Measuring your weight is simple, step on a scale and see if it went up, down, or stayed the same. When measuring fat loss, things get more complicated. Here are a few ways that you can measure your fat loss progress. 

Bioelectrical impedance analysis – Many scales now include a Bioelectrical impedance analysis BIA. This is where an electrical signal is sent through the body, measuring fat-free mass and body fat percentage.

Skinfold calipers – Skinfold calipers are a tool used to measure the thickness of your skinfolds. This helps you determine body fat percentage. 

Physical Measurements –  Taking measurements with a measuring tape. This method can provide you with your waist size, hip circumference, and other measurements to help you track body composition changes. 

Progress pictures –  Tracking progress by taking pictures of yourself in the same positions, with the same lighting and clothes, is a great way to document your journey. 

Hydrostatic weighing – Underwater weighing involves sitting on a chair suspended in water, measuring how much water has been displaced when you sit, and accurately measuring your body composition. 

Bod Pod –  A Bod Pod is a device that uses air displacement to measure body composition. It’s considered one of the most accurate methods for measuring body fat. 

The best way to measure fat loss progress is what works for you. You must choose something easy to do regularly that gives you accurate results. For more information, read How To Take Body Measurements For Weight Loss.

How weight loss can affect your metabolism

Weight loss can significantly affect your metabolism in multiple ways. Firstly, it influences your hunger hormones, causing a decrease in leptin and an increase in ghrelin. This hormonal shift can increase feelings of hunger, even after consuming a meal. 

Secondly, weight loss often involves a reduction in muscle mass. Muscles are energy-demanding organs contributing significantly to your resting metabolic rate (RMR). Therefore, losing muscle mass can decrease your body’s ability to burn calories at rest. 

Lastly, a calorie deficit often used to lose weight may lead to decreased physical activity. This subconscious reduction in movement, a phenomenon referred to as non-exercise activity thermogenesis (NEAT), further contributes to the slowdown of your metabolism.

How to lose body fat and maintain muscle? 

Losing body fat and maintaining muscle involves three foundational principles, resistance training and eating the appropriate amount of calories and protein. Let’s look at each in more detail. 


It’s important to consume enough calories to support your daily functions. This is known as your total daily energy expenditure. For most people, maintaining energy balance or slightly reducing calorie intake below this threshold can promote fat loss. learn more about calorie deficit diets.


Protein is a vital macronutrient for both fat loss and muscle maintenance. It keeps you feeling fuller for longer and supplies the essential amino acids necessary for building and repairing muscle tissue. Learn more about Macros For Building Muscle.

Resistance Training

You’re essentially stressing muscle tissue and triggering an adaptive response when performing resistance training. This response causes muscles to become stronger, grow in size, and, more importantly, become more metabolically demanding. As a result, your resting metabolism increases as your body works to sustain new muscle tissue. 

How do you prevent weight gain? 

Losing body fat and weight can be challenging, as it requires significant lifestyle changes. However, maintaining these habits beyond the diet phase can present an even greater challenge.

If you want to prevent weight gain, here are a few tips: 

  • Monitor your hunger and satiety hormones. Eating when you’re hungry and stopping when you’re full can help keep your appetite in check. 
  • Keep moving. Regularly participating in physical activity will help maintain energy balance by increasing total daily energy expenditure. 
  • Get enough sleep. Short sleep duration has been linked to an increased risk for weight gain and obesity.
  • Track your progress. Tracking your weight and food intake can help you make lifestyle changes that are more sustainable in the long run. 
  • Lift weights. Resistance training is a great way to build muscle and maintain your metabolism. 
  • Join a support group.  Research has shown that having a support group can significantly increase weight loss success. 
  • Stay mindful of what you eat. Being mindful of your eating habits will help identify why you are making poor food choices and will help you correct the source of the problem. 
  • Eat more fiber and protein. Eating high-fiber and protein foods can help keep you feeling fuller for longer, which in turn helps with appetite control. 

Frequently asked questions 

Can you lose fat and not lose weight?

You can lose fat without losing weight by consuming enough calories, getting adequate protein, and doing regular resistance training. This promotes muscle growth while reducing body fat. So, even if you’re losing fat and gaining muscle, your weight may stay the same due to the added muscle weight.

How do you know if your body is burning fat?

Determining whether your body is burning fat or storing it can be challenging. However, by maintaining a calorie deficit and closely monitoring your weight and body fat, you can leverage this data to assess your body’s fat-burning progress. A positive sign of fat burning is observing a consistent downward trend in both weight and body fat percentage.

Why am I losing weight but not fat?

If you are experiencing weight loss without a corresponding loss of fat, you are likely shedding water weight, muscle mass and depleting glycogen stores. This phenomenon is often attributed to following extremely low-calorie diets and engaging in rigorous exercise programs, typically occurring within the initial weeks of a weight loss journey.

How long does it take to notice fat loss?

It takes time and consistency to notice changes in body fat. However, the timeline depends on diet, exercise, health status, lifestyle habits, and genetics. From what I have seen, it can take up to 4-6 weeks for initial results and 8-12 weeks for noticeable progress to appear. 

Where does the fat go when you lose weight?

The body’s excess energy is broken down, repackaged, and stored in cells. Eventually, it gets released into the bloodstream as fatty acids and is converted into energy by other organs. Once the fatty acids have been used, what remains are carbon dioxide and water, which are then exhaled. This process is called lipolysis and cellular respiration.

Final thoughts

Fat loss is a journey that requires patience, consistency, and commitment to achieve lasting progress. Understanding what factors can influence fat loss and how it differs from weight loss can help you create habits that promote muscle growth, preserving lean body tissue. 

It is important to remember that fat loss progress should be monitored regarding body composition rather than weight. Regularly measuring your body fat percentage can help you understand how much fat you are losing and prevent you from becoming discouraged when not seeing results on the scale. 


Remember: this post is for informational purposes only and may not be the best fit for you and your personal situation. It shall not be construed as medical advice. The information and education provided here is not intended or implied to supplement or replace professional medical treatment, advice, and/or diagnosis. Always check with your own physician or medical professional before trying or implementing any information read here.

Noah Quezada is a Registered Dietitian Nutritionist located in Denver, Colorado. Over the course of more than a decade, he has gained extensive experience in helping clients manage their weight through in-person sessions. Noah is also the 2023 President of the Colorado Academy of Nutrition and Dietetics.