But muscle is heavier than fat, right?

This isn’t a trick question but we do require a little more detail and an explanation in order to answer it.

I am addressing this as I hear it so frequently among gym members in relation to their body composition, either due to them wanting to gain size or trying to lose weight but fighting against the scales. I would like to provide some rationale behind this and possibly even encourage a life without any weighing scales at all!

So how can we compare muscle with fat? I am not going to suggest that the question of whether muscle weighs more than fat is the same as asking whether bricks weigh more than feathers, 1 Kg of bricks of course weighs the same as 1 Kg of feathers — you are comparing the same unit of weight (1kg) just in two different materials. That is a sort of trick question. Comparing weight to weight in this context is pretty pointless, but the key idea here is that it is much more useful to compare weights of different materials per unit of the same volume i.e. a bucket of muscle with a bucket of the same size, filled with fat.

Now to put this into the context of our muscle verses fat discussion and shed some light on why it can seem impossible to move the scales. Losing weight can be a long, slow and non-linear process and naturally people are eager for the number on the scale to reduce as each week (or day!) passes. Despite the consistent exercise routine and careful moderation of diet, the rate of weight loss is remarkably slow and some weeks may not be at all. But what actually is the goal here? Specifically, the aim really is to lose fat mass (weight) rather than overall body mass and most scales do not detail such information. In the majority of cases, the scales only provide the total weight of the body — bones, fat, muscle and all of the trimmings that make up the composition of our body. I will refer to fat loss from now on. So perhaps the value of overall body weight is useful when those are restricting their energy intake without any change in the amount of energy being used i.e. when diet is controlled in the absence of increasing activity levels or exercising. However, physical activity and regular exercise are strongly encouraged to maximise the rate of fat loss due by enhancing the amount of energy expended each day. If calorie, or energy, intake is also limited, the result will be a negative energy balance and overall loss of energy stores (i.e. fat). Resistance exercises that will stimulate muscle growth and lead to overall muscle gain will increase the daily amount of energy used. In fact, those with a great percentage of muscle on their bodies (named skeletal muscle), generally burn more calories than someone of the same body size with less muscle, even when they are sleeping or at the pub. This is why weight-based exercises that build lean tissue (muscle) are an extremely efficient way to lose fat compared to solely relying on cardiovascular dominant exercises (jogging, rowing, Zumba) for overall fat loss.

Building muscle through exercise, particular strength or weight- based exercise, can cause disappointment however, as the rate of weight loss may be slow or seemingly non-existent. But they are changing (and significantly improving) their body composition; fat cells are shrinking as stores are being used for energy and their muscles are developing in strength and mass. I am not talking about bulking up or gaining huge size (unless that is your goal), in fact, the often people also comment that their clothes are too big or they have gone down two dress sizes but haven’t lost any weight.

So why does replacing fat with muscle seem to create a smaller overall body size? The principal factor responsible lies in both tissues structure; muscle is much more compact than fat, muscle is about 15% denser than fat. Or to change it around, fat cells takes up much more space per weight than muscle. In fact, the density of our skeletal muscle is around 1.06 kg/litre whereas fat tissue is just 0.92 kg/ litre. This is why measuring BMI (body mass index) alone is not always an accurate indicator of health or weight management as values are solely calculated from weight and height. Some body builders can be categorised as severely obese, despite having a fat percentage of around 5%!

To get an accurate assessment of progress would be to measure your body’s composition every 2- 4 weeks, which will provide the breakdown fat and muscle. In the Lifestyle’s fitness suits, we have such equipment: a Tanita body analyser, a set of scales which has been validated to accurately provide as assessment of your composition.

But muscle is heavier than fat, right?

Yes if you are comparing the same volume.

So should we focus on building more muscle rather than just weight loss?

Yes for a leaner, stronger and healthier body regardless of body weight. After all, strong seems to be the new skinny right?

So should we just ditch the weighing scales altogether? ….