My Saturday weigh-in was, on the surface, a little disappointing. My weight had fluctuated up this week, with Tuesday’s weigh-in showing a completely unexpected 3.1 lbs / 1.4 kg increase!

While I did cut my Monday 36-hour fast short, I had two 36hr fasts the previous week, and stuck to strict keto principles – as well as increasing my swimming, running, and introducing cycling and more mobility and strength work! So, a weight gain was not something I had factored in at all! But maybe I should have.

As we’ve discussed before, the body is not a simple machine of inputs and outputs – it’s a complex metabolic maze – a puzzle at times. While on paper I am maintaining a calorie deficit, I’m also increasing exercise, which requires muscle repair, which in turn requires water.

Think of it like building a wall. 🧱

You need bricks (essential proteins), sand, and cement (the hormonal signals and micronutrients that bind it all together), and also water to get the right consistency. So the body retains extra water to build the muscle.

It takes energy to put up the brickwork, and likewise, it takes energy to build muscle. But how is that possible if I’m fasting and therefore at a calorie deficit? There’s a common misconception that you have to be in a calorie surplus / excess in order to build muscle, but that’s simply not the case. As long as you have fuel and the right building blocks you can build muscle.

We use fat to fuel everyday bodily functions during ketosis, and we use the same fat to build the wall, which increases the deficit.

Only once the muscle is built is any excess water released. But since we’re tearing down the walls and building new ones (more exercise, resulting in stronger, more efficient muscles) every week, the body is never too eager to let go of its building materials.

“Muscle is heavier than fat”…isn’t it?

We often hear that ‘muscle weighs more than fat,’ but of course that’s nonsense – a pound of feathers weighs the same as a pound of iron!🪶⚖️

But it is true that muscle is denser than fat. Almost 20% denser, so muscle on your body takes up 20% more space than your body fat did. That is why my jeans are falling off me even though the scale is holding steady at 99.6kg!

Plus, there’s a massive metabolic cheat code here: muscle is active tissue. Every pound of muscle I build burns about three times more calories at rest than fat does. By trading fat for muscle, I’m building a bigger, hungrier engine that burns calories even while I sleep.

The mirror, tape, and scale

When we exercise while also maintaining a calorie deficit, it’s therefore important that we relegate the scale to more of a general guideline.

The mirror and the measuring tape are more reliable sources of data than our body weight. As we’ve seen in the past, my weight fluctuates a lot, even over a day or two, far more than is possible due to fat gain and loss. I “gained” 3.1 lbs / 1.4 kg in just 3 days, then “lost” 2.3 lbs / 1 kg in four days. Neither fat nor muscle are gained or lost that rapidly.

What we’re doing when we exercise is not about weight loss, it’s about body recomposition. We are literally converting body fat into muscle, and that requires water, which CAN fluctuate hugely over the course of a few hours let alone days.

So over time, there will definitely be a net loss in weight, as we lose fat and turn it into muscle, which in turn burns more energy – but while we’re rebuilding, the scales might tell us otherwise.

What I’ve really noticed this week is how much better I look in the mirror. I can see my abs and oblique muscles starting to show, and a lot more size as well as definition in my legs.

So, the net result of this week’s recomposition effort is that I’m back down to 15st 9.5lbs (219.5lb/99.6kg). So I’m still under that 100kg mark, but also a much more svelte-looking version!

Anyway, I’m going to worry less about the scales, and more about my recomposition efforts – plenty of high-quality protein, lots of exercise, intermittent fasting, and plenty of rest. The rest will take care of itself.