Fat loss vs weight loss: Why the difference matters more than you think

There is so much discussion around fat loss and weight loss that it can be an extremely confusing topic to navigate. In part, due to the terms being used interchangeably when they actually refer to different things. 

As women, we've got lots to consider, including hormone fluctuations when it comes to muscle mass and weight loss.

The good news? There are a few fairly simple changes you can make to improve your lifestyle.

But first, there are a couple of things you need to know, including the difference between weight loss vs fat loss. Let's dive into it.

What's the difference between weight loss and fat loss?

Put simply, weight loss refers to an overall decrease in weight, whereas fat loss refers solely to the body fat percentage lost. These are often used interchangeably, but they aren’t the same. 

We often use weight loss as a catch-all term when we’re actually referring to losing body fat.

Is one better than the other?

Our body mass is made up of 2 components: fat and lean body mass (also referred to as muscle mass), which includes muscle, bone, water, and our organs. 

Lean body mass is important for a variety of reasons. It helps protect bone density, which is important as you get older, to avoid osteoporosis and frail bones. This is particularly important through perimenopause and menopause, as the change in hormones accelerates bone loss substantially during this time [1].

It can impact your metabolism and basal metabolic rate since muscles require more energy (calories) at resting levels than fat. Too much fat accumulation can cause health problems like diabetes and cardiovascular disease (not always, so it’s important to take things case by case). 

If you become ill, having optimal lean body mass can help aid recovery, and a study looking into ICU patients found that those with low lean muscle mass or poor skeletal muscle quality may have more specific nutritional needs [2].

For these reasons, lean body mass is far more useful to our bodies than fat. 

When you step on the scales to see you’ve lost weight, all you see is your overall body mass loss, without any knowledge of whether that loss is fat or muscle. Since we want to maintain our lean body mass, especially as we age, that makes fat loss better than weight loss.

That’s because we know we’re losing fat, of which one doesn’t want surplus to avoid health conditions, rather than losing lean body mass through overall weight loss. 

Can you lose fat without losing weight?

Yes, you can absolutely lose fat without losing weight. You can gain muscle and lose fat without seeing any changes when you step on the scale because muscle is denser than fat. 

In fact, you can actually lose fat, increase muscle and gain weight but still be considered “healthier” than before.

How to tell if you're losing fat, muscle or water

This is where things can get a little tricky — it’s not like your scales can tell you exactly where you’re losing weight and how! Unfortunately, it’s not that simple. 

Let’s start with water. Water is crucial to our bodies, we can only survive 2-4 days without it, and it makes up approximately 45–75% of our body weight [3]. Water retention (medically known as edema) is anything beyond that range. 

Water weight commonly refers to a build-up of fluid that causes bloating and puffiness, often in your ankles, feet, and legs, with stomach bloating. As water weight isn’t real weight gain in the way that muscle and fat are, you might find that your weight fluctuates a lot. If you’re finding you’re often bloated and your weight can go up and down, water retention could be to blame. 

This retention can also be worsened by not moving enough (this can be as simple as gentle walking throughout the day) and large amounts of salt. Making sure you're varying your sodium intake can help.

If you’re finding your water retention is severe and impacting your day-to-day, be sure to get in touch with your doctor because, in some cases, it can indicate conditions like kidney disease and heart problems [4]. 

Next up is fat. Losing inches, especially around your middle, can be a sign of fat loss. You may also notice that with losing fat, you generally feel better and more healthy in yourself. It’s less about what the scales are saying and more about how you’re feeling and whether you achieve inch loss.

If you're really serious, you can get a body fat scale, which, unlike weight loss in total, looks into excess fat and lean mass to give you a better picture of your ideal body fat percentage.

Finally, muscle loss. The first sign of muscle loss is rapid weight loss. The next is feeling overly tired and sluggish during exercise. Muscle loss becomes more prevalent as we age (which is called sarcopenia), so it is something to be particularly cognisant of [5]. 

How to lose fat whilst maintaining or gaining muscle

In the past, when it came to losing weight, programmes were focused more on the scales and overall body mass decreased. Now, we understand more about body composition and that to safely and effectively lose weight, gaining and maintaining muscle is incredibly important. 

The main way to maintain muscle whilst losing fat is through regular exercise. It’s said that a combination of cardio and weight training can help minimise muscle loss whilst ensuring you primarily lose fat.

Do weight loss medications help with fat loss or contribute to muscle loss?

Prescription weight loss medications like Wegovy (semaglutide) and Mounjaro (tirzepatide) work by mimicking natural hormones that regulate appetite, slow digestion, and improve blood sugar control. They're designed to help reduce body weight by curbing appetite and lowering calorie intake — but what about body composition?

Clinical research suggests that most of the weight lost on GLP-1 medications comes from fat, particularly visceral fat, which is linked to long-term health risks [10]. However, some muscle loss can still occur, especially if the person isn't consuming enough protein or engaging in resistance training during treatment.

That's why it's so important to pair these medications with a nutrition plan focused on preserving lean muscle mass and an exercise routine that includes strength training. Mounjaro and Wegovy can be effective tools for targeting fat loss — but achieving a healthier body composition depends on more than the medication alone.

Ways to sustainably lose fat

It’s important that if you’d like to go on a fat loss journey, you do so sustainably and sensibly. This is to make sure you don’t compromise your health whatsoever. 

The aim of any programme to lose weight is to maintain your muscle mass, especially if you’re going through menopause. 

Exercise

Finding an exercise that you like and do regularly is the key here. Little and often is better than not at all. 

There are certain exercises that are particularly good for increasing muscle, including resistance training (which we mentioned earlier) and aerobic exercise combined [6]. These exercises can be particularly great for women going through perimenopause and menopause [7]. 

No restrictive calories or diets

When it comes to diets, it’s often more helpful to think about what you could add to your meals than what you can take away.

For instance, instead of thinking about cutting back on fries with your meals, consider adding a portion of leafy greens. If you're trying to build muscle mass, think about having a protein-rich diet to help with muscle growth.

It can even be as simple as throwing some extra nuts in with your breakfast or swapping out a fizzy energy drink for a black coffee or hot lemon water.  

Over time, these changes will become more ingrained in meal prep, and you won’t necessarily always want to have larger portions or less-healthy aspects of a meal. That way, you won’t feel restricted and are more likely to implement changes. 

Water intake

As we mentioned earlier, our bodies are composed of 45-75% water, which is essential to our functioning. That’s why it’s essential to stay hydrated. A 2016 study notes that keeping on top of water intake can help with weight loss [8].

Sleep more

OK, this one isn’t directly related to fat loss, but it is incredibly important to overall well-being, reducing many health risks and supporting metabolism [9].

Get help when you need it

The truth is, there’s no quick fix when it comes to healthy fat loss and muscle gain, and sometimes you might need some support along the way.

That's where Juniper’s Weight Reset Programme comes in. Designed specifically for women with science-led and pharmacist-prescribed breakthrough medication, dietitian support, and coaching to encourage healthy weight loss, this is a medical pathway for long-term weight loss.

With medication that suppresses your appetite and improves metabolic function as well as health tracking and lifestyle and habit changes, our UK clinicians, dietitians, and health coaches are here to help you find your confidence again.