Losing weight vs losing fat: what’s the difference?

At FFF we frequently get requests to help clients lose X amount of weight – often in an ambitious time frame to say the least.

Losing weight vs losing fat: what’s the difference?

Weight loss is not necessarily the same as fat loss and not all weight loss is a good thing.

“We need some degree of body fat (women more than men), to stay healthy.”

We sometimes get carried away with the number on the scale and go to extremes to get the number down as quickly as possible. However, the number says less than you think and aiming for quick fat loss can often do more harm than good in the long run.

Let’s look at what a healthy body composition is and how much (non)sense it makes to measure this with a scale.

What is a healthy body composition?

We have a lot of fancy terms for it, getting “shredded”, “hench”, “lean” or “toned” but when it comes to body recomposition we can only really impact 2 factors: muscle mass and fat mass.

“A healthy body fat percentage is up to 25% for men and up to 30% for women.”

Muscle mass is not the same as lean mass, as lean mass also comprises bone mass, water and organ weight. Aside from the practical benefits of having muscle mass such as being able to perform physical daily tasks easily, having muscle mass makes you burn more calories which means you can eat more without gaining fat and it keeps your bones strong.

Losing muscle is one of the main factors that causes the negative effects of aging. Age-related sarcopenia is the loss of muscle mass due to age. This occurs from as early as 25 (3) and reduces your skeletal muscle mass gradually to about 70% by the time you’re 80. It can’t be avoided, but the process can be slowed down by doing resistance training and an adequate protein intake (4).

We need some degree of body fat (women more than men), to stay healthy. Dietary fat is important for many bodily functions:

  • Energy Storage
  • Production of hormones
  • Protection of organs and capillaries
  • Supports a healthy immune function

As a rough measure a healthy body fat percentage is up to 25% for men and up to 30% for women but varies widely between individuals (5).

What does the number on the scale mean then?

The problem with taking your weight as your only measure of progress is that it cannot tell you what the weight is made of. Some factors, such as water weight can fluctuate on a day to day basis depending on how long it has been since you last trained, how stressed and how hydrated you are. For women, the time of the month can affect how much water you are holding on to (1). For example, if you are holding on to water because you are very stressed, this can mask fat loss and make you think you are not on the right track, when you are actually doing really well, which can be very demotivating.

Conversely, if you go on a very low carbohydrate diet you will initially lose a lot of weight simply because you lose a lot of water. This is because water is needed to store carbohydrates. This may falsely be perceived as fat loss while actually, you are not in a calorie deficit at all and you need to revise your diet.

However, these are relatively short term changes. Eventually fat loss will catch up with the water retention and water loss can only account for weight loss to some extent.

When is weight loss not a good thing?

If your focus is losing weight, rather than losing fat you might embark on methods such as very aggressive and unsustainable calorie deficits, that waste a lot of muscle in the process. If half of the weight you have lost is muscle tissue this can be negative in the long run, especially if the weight loss is then followed by weight regain, which is the case for most dieters (2,6).

“By ‘yo-yo-ing’, you can develop what is called sarcopenic obesity: when you have low muscle mass combined with a high body fat percentage”

Even if you end up back at your old weight after your crash diet, your body composition has changed towards a higher fat and lower muscle mass. As muscle burns more calories than fat, this means you need to eat less calories than before to avoid gaining more weight. If this is taken to extremes by losing and gaining weight, in other words, by yo-yo-ing, you can develop what is called sarcopenic obesity: when you have low muscle mass combined with a high body fat percentage (4). This phenomena is more popularly referred to as being “skinny fat” and it is possible to have a healthy weight with this condition.

A focus on weight loss rather than fat loss can also mask positive results in the long run. For example if an adequate calorie deficit, combined with resistance training leads to muscle gain and fat loss at the same time. Muscle weighs more per volume than fat so it is possible to gain muscle and lose fat at the same time while your weight stays the same. Your body composition has shifted to a lower fat percentage but because you only see your weight hasn’t shifted you think you haven’t made progress, and this is not the case!

How should I track my progress then?

I’m not saying keeping track of your weight is completely useless because for most people overall it tends to be a good indicator of how well you match your calorie intake to your expenditure. Measuring your weight can be a good tool to see trends over a long period of time, but don’t use it as the only measure of progress. When you have a fat loss goal, use other measures too, such as:

  • Hip to waist ratio
  • Progress Pictures
  • Assess how well your clothes fit
  • Girth Measures
  • Bioelectrical Impedance Machine

But don’t get too caught up in numbers all together – what matters most for achieving and more importantly, maintaining fat loss is building healthy habits.

  • Maintain a healthy diet
  • Exercise Regularly
  • Prioritise your sleep
  • Manage your sleep

As long as you are moving in the right direction, success will only be a matter of time.

If you are currently on our Fat Loss plan and are not seeing the results you would like to, book a call with our Nutrition Team, to discuss your progress so far.


  1. Bunt, J.C, Lohman, T.G. and Boileau, R.A. (1989). Impact of total body water fluctuations on estimation of body fat from body density. Medicine and Science in Sport and Exercise, 21(1), 96-100.
  1. Curioni, C.C. and Lourenco, P.M., 2005. Long-term weight loss after diet and exercise: a systematic review. International journal of obesity, 29(10), p.1168.
  1. Lexell, J., Taylor, C.C., Sjöström, M. (1988). What is the cause of the ageing atrophy? Total number, size and proportion of different fiber types studied in whole vastus lateralis muscle from 15- to 83-year-old men. Journal of Neurological Science, 84(2-3), 275-294.
  1. Lee, D. C., Shook, R. P., Drenowatz, C., & Blair, S. N. (2016). Physical activity and sarcopenic obesity: definition, assessment, prevalence and mechanism. Future science OA, 2(3), FSO127.
  1. Sun, G., French, C.R., Martin, G.R., Younghusband, B., Green, R.C., Xie, Y., Matthews, M., Barron, J.R., Fitzpatrick, D.G., Gulliver, W., Zhang, H. (2005). Comparison of multifrequency bioelectrical impedance analysis with dual-energy X-ray absorptiometry for assessment of percentage body fat in a large, healthy population, The American Journal of Clinical Nutrition, 81(1), 74–78.

6. Wing, R.R. and Phelan, S., (2005). Long-term weight loss maintenance, The American Journal of Clinical Nutrition, Volume 82, Issue 1, July 2005, Pages 222S–225S

Fresh Fitness Food provides personalised meals plans delivered straight to your door, ensuring not only that you have the nutrients you need to manage your stress levels, but also that you have the time usually spent shopping, cooking and washing up, to engage in your favourite stress reducing activity. To discuss which nutrition plan is right for you, book a call with our in-house nutrition team here.

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Meghan Foulsham

Published by Meghan Foulsham

Meghan's fascination with metabolism and the effect of diet on the body covered in her BSc Biochemistry, paired with being a passionate mental health advocate, led her to a Master's degree in Eating Disorders and Clinical Nutrition. Using this, Meghan works with clients to help them reach their goals in the most sustainable way, without sacrificing or risking their mental health.

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