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

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

The thrill of stepping on our bathroom scales and seeing a lower number than the last time we weighed ourselves is something many of us are familiar with. Weight, after all, is an emotive issue. If yours is what you consider ideal it can make you feel on top of the world. But if you weigh more than you think you should, it can knock your self-esteem.

Looking good and feeling great are strongly linked with body weight. We see our weight as the gold standard measurement of how healthy, fit and even attractive we are. But do we really mean weight?

Whether you’re trying to drop a few pounds to be healthier or to look slimmer – or both – it’s likely that what you’re really trying to achieve is fat loss rather than weight loss. Having excess body fat is the real reason you struggle to squeeze into your favourite skinny jeans or look good lounging by the pool. Or to put it another way, your ideal body type owes more to how much fat you’re carrying than that number on your bathroom scales. And if you have too much of it, it doesn’t just make you feel uncomfortable, it can affect your health and your internal organs too.

The difference between weight loss and fat loss can, however, be confusing. Because of the way we’re conditioned to think about body weight it may not be easy to accept that you can look slimmer without shedding a single pound. The concept that you could be slimmer yet at the same time several pounds heavier is even harder to swallow.

However, this is exactly what can happen when you lose fat and gain lean muscle. Why? Because muscle is much denser than fat, so pound for pound it takes up less space in the body (this is why it’s often said that muscle weighs more than fat).

Body weight measurement

It’s possible that we talk about achieving an ideal body composition in terms of losing weight because keeping track of our weight is relatively simple. Weighing scales are found in most modern bathrooms, and anyone can easily weigh themselves at their GP’s surgery or a local gym or pharmacy. 

However as anyone who steps on their scales frequently knows, body weight can fluctuate – not just from day to day, but from hour to hour (and perhaps also minute to minute in certain circumstances). That’s because when you weigh yourself you’re weighing every part of you, including your muscles, your fat stores, your bones, your blood, your organs, how much water you’re retaining and even the weight of any food you’ve eaten that hasn’t been digested and waste matter that hasn’t been excreted.

This means your weight can increase slightly if you’ve just had a big drink of water or eaten a big meal, or if you had too much salt that day (since sodium in salt makes your body retain water). Similarly, when you lose water through sweating or urination, your weight can drop almost instantly.

Muscle and fat burning

Weight is also an ideal measurement if you’re on an extreme diet because losing weight rapidly can give your motivation a major boost. But the faster you lose weight, it’s very likely that the higher the percentage of that weight will come from muscle. And that’s probably not a good thing, since muscle is what gives you that lean, toned look you may be aiming for.

Losing muscle is also not a good idea because the more muscle you have, the more calories you’ll burn, since muscles burn more calories at rest than fat and some other tissues (i). If you’re losing muscle you may also find you’re running low on energy, which means you may find it harder than usual to work out and take part in your normal everyday activities.

This is why preserving your muscle mass – or better still, gaining muscle – while losing fat is the ideal way to improve your body composition, as opposed to simply losing weight. Losing fat means reducing your body fat percentage, which represents the amount of fat your body is carrying. And having less body fat doesn’t just make you look better, it can make you healthier too, since having too much of it can lead to heart disease and diabetes, among other health conditions.

Body fat measurement

The problem with body fat, however, is that it’s much more difficult to track than weight. There are several methods you can use, including:

  • Skin fold measurement – this is a technique used by personal trainers and other health professionals that involves using callipers to pinch certain points of your body.

  • Professional scans such as DEXA and 3D body scans may be more accurate than other methods of measuring body fat, but they’re far from widely available yet (some gyms may have them, or you can have your body composition measured at a private scanning facility for a price).

  • Home body composition monitors that look like high-tech bathroom scales are widely available, but it’s unlikely they’re particularly accurate (though they can give you a rough idea of your body fat percentage and how much body fat you may be gaining or losing).

You can also use low-tech methods such as taking body measurements (measure your waist, hips and neck at the same time each week, for instance). Alternatively forget about numbers and go by the way you look and feel. Try taking a full-body selfie once a month wearing the same clothes and in the same lighting and compare. How your clothes fit can also be a good indication of whether or not you’re losing body fat.

How low should you go?

So how much body fat should you have if you want to look slim and stay healthy? The American Council on Exercise suggests the ideal body fat percentage for a non-athlete woman is 25 – 31 per cent, and 18 – 24 per cent for non-athlete men (women need a higher body fat percentage than men to support their reproductive health). Athletic and very fit people, on the other hand, tend to have a lower level of body fat – 14 – 20 per cent is ideal for a female athlete, while male athletes can go as low as six per cent (ii). 

However, fit you are, while it may be tempting to cut your body fat as much as possible there are disadvantages of having too little. Our bodies need fat for lots of reasons, including hormone production and nutrient absorption. If your body fat percentage is too low you may feel tired and irritable, and if you’re a woman you may experience problems with your menstrual cycle. Other things that can happen when your body fat percentage is far less than ideal include:

  • Mood swings

  • Low blood pressure

  • Hair loss

  • Dry skin and nails

  • Oral health problems

  • Muscle cramps.

The American Heart Association also suggests we need fat in our diets for energy, to support cell growth, to protect our organs and to help keep our bodies warm (iii).

Fat-loss strategies

Talking about losing body fat is easy. But achieving it can be complicated and often frustrating. Unlike losing weight, losing body fat can be a slow process. According to the American Council on Exercise, most experts agree that losing just one per cent of your body fat a month is safe and achievable (ii). In other words, you may need to be patient. 

There are also some considerations to bear in mind if you want to try to lose fat without letting go of too much – or preferably any – muscle:

Working out

Exercise is important for fat loss, but which type should you do? Cardiovascular exercise burns fat effectively, but resistance training helps build muscle. And building muscle is important for fat loss because more muscle means you’ll burn more calories at rest. Indeed, according to the American College of Sports Medicine, while resistance training may not be helpful for weight loss it may increase muscle mass while at the same time increasing loss of fat mass (iv).

Weight training has other calorie-burning benefits too, with studies suggesting you may burn more calories during the hours following a weights session than a cardio session (v). Another study has found that the calorie-burning effect of a weight training session may last for up to 38 hours (vi). 

However, many experts believe a combination of cardio and resistance training may be the ideal solution if you’re trying to lose fat and gain muscle. Experts writing in the Journal of Applied Physiology found that people who did both cardio and weight training over a period of eight months achieved better body composition changes, losing weight and fat while at the same time gaining muscle, than others who did just cardio or just weight training for the same amount of time (vii).

Eating healthily

Since losing weight quickly isn’t your aim, you may want to have more calories than you would if you were following a weight-loss diet to make sure you don’t sacrifice any muscle. Try to work out the maximum number of calories you can eat while still losing some weight – as little as 1lb a week, for instance – and most of that weight should come from body fat.

Try to make sure you get plenty of protein in your diet by eating lean meat and dairy products as well as plant protein in beans, pulses, nuts, seeds, tofu, Quorn, seitan and tempeh. Fat is important for building muscle too, plus foods that contain fat can help you feel fuller for longer by slowing down your rate of digestion (try to include some ‘good’ fats in your diet, such as oily fish, nuts, seeds, avocados and extra virgin olive oil).

Meanwhile it’s a good idea not to avoid carbs because they’re your body’s primary source of energy – and if you’re working out you’re going to need plenty of energy. Also, if you’re not eating enough good-quality carbs – whole grains, for instance – your body will convert protein into energy instead, which means all that protein you’re eating won’t be used for building muscle.

Supplementary benefits

There are a few supplements that may help you achieve your ideal body composition, including the following:

Branched-chain amino acids (BCAAs)

Consisting of the amino acids isoleucine, leucine and valine, BCAAs may be helpful if you want to maintain muscle mass while losing weight. Indeed, there is some evidence that suggests taking a BCCA supplement may help you maintain lean muscle and lose fat while doing weight training, even if you’re following a low-calorie diet (viii). BCCAs are also found in many protein sources, notably animal foods such as meat, dairy products, eggs and fish.

Protein products

Eating more protein isn’t always easy to achieve, but you can boost your protein intake by using products such as protein shakes and protein bars – these are particularly convenient if you want some protein while you’re training or after exercise to help build muscle. Vegetarians and vegans may want to try a plant protein product, such as pea protein powder.


This amino acid is used by the body to turn the fat in your cells into energy, so it may be helpful if you want to burn more fat without losing muscle. It’s produced naturally in the body, with food sources including red meat and dairy foods. Look for a supplement in tartrate form, as this is thought to have a high absorption rate.

Green tea extract

Often associated with increased fat burning, many athletes and slimmers take green tea supplements to support weight loss. One study also suggests it may help you burn more fat when you exercise (ix), while another found substances in tea called catechins may increase fat burning both during exercise and while you’re resting (x).


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  5. , et al. American College of Sports Medicine Position Stand. Appropriate physical activity intervention strategies for weight loss and prevention of weight regain for adults. Med Sci Sports Exerc. 41(2):459-71. Available online:

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  7. , , Effect of an acute period of resistance exercise on excess post-exercise oxygen consumption: implications for body mass management. European Journal of Applied Physiology. Volume 86, Issue 5, pp 411–417. Available online:

  8. , et al. Effects of aerobic and/or resistance training on body mass and fat mass in overweight or obese adults. J Appl Physiol. 113(12):1831-7. Available online:

  9. , , In a single-blind, matched group design: branched-chain amino acid supplementation and resistance training maintains lean body mass during a caloric restricted diet. Int Soc Sports Nutr. 13:1. Available online:

  10. , et al. Green tea extract ingestion, fat oxidation, and glucose tolerance in healthy humans. Am J Clin Nutr. 87(3):778-84. Available online:

  11. , et al. Effects of Combination of Regular Exercise and Tea Catechins intake on Energy Expenditure in Humans. J of Health Sci. 51(2) 233-23. Available online:

Our Author - Christine Morgan


Christine Morgan has been a freelance health and wellbeing journalist for almost 20 years, having written for numerous publications including the Daily Mirror, S Magazine, Top Sante, Healthy, Woman & Home, Zest, Allergy, Healthy Times and Pregnancy & Birth; she has also edited several titles such as Women’ Health, Shine’s Real Health & Beauty and All About Health.

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