Mert

One small correction to "no energy expenditure": there is a little, because holding your legs in contact with moving pedals involves some low-level muscular activity, and you are not perfectly passive.

It is a rounding error compared with actual activity, though. If the question is whether it contributes to a calorie balance, treat the answer as no.

One measurement worth doing, since it turns this from an estimate into your own number: set up in a push-up position with your hands on a bathroom scale and read it.

That gives you the actual load your arms carry, for your body, at your hand position. Repeat with your feet on a chair and read it again. It takes two minutes and it makes the whole progression concrete rather than theoretical.

You breathe it out. That is the entire answer and it is one of the most consistently surprising facts in physiology.

Fat is mostly carbon, hydrogen and oxygen. Metabolising it combines those with oxygen you inhale, and the products are carbon dioxide and water. The carbon dioxide leaves through your lungs and the water leaves as sweat, urine and water vapour in your breath.

When the proportions are worked out for a typical fat molecule, the great majority of the mass — roughly four fifths — leaves as carbon dioxide through the lungs. The remainder leaves as water.

So the lungs are the primary excretory organ for body fat. Losing weight is, quite literally, exhaling it.

Which also explains the thing that seems paradoxical about your ride: you were breathing enormously hard for twenty hours, and that heavy breathing was not merely a symptom of the effort. It was the mass leaving.

Worth adding what does not show up in the visible outcome: injury rates in intensive basic training programmes are not low, and overuse injuries are a well-documented cost.

You see the recruits who finished. The ones who developed stress fractures or tendon problems are not in the photograph, and their absence is exactly what makes the method look more effective than it is.

That survivorship effect is worth remembering whenever a demanding programme is offered as evidence that recovery is optional.

The difference is that a living body is not a fixed object being used up — it is continuously being rebuilt, and the rebuilding is what responds to demand.

Your tissues are replaced constantly. Bone is dissolved and rebuilt, muscle proteins are broken down and resynthesised, blood vessels are remodelled. The relevant question for a living structure is not how much use it has had, but what instructions the rebuilding process is receiving.

And the instructions come from load. A bone under repeated stress is rebuilt denser along the lines of stress. A muscle repeatedly asked for force is rebuilt with more contractile protein. A heart repeatedly asked for output gets better at producing it.

A shoe has no such process. It is manufactured once and then only degrades. If shoes continuously replaced their own material in response to use, they would get thicker where you walk hardest, and the analogy would run the other way.

One thing worth being honest about: three days a week is not a law, and plenty of people train four or five days as beginners and do fine.

What is close to a law is that each muscle group benefits from being trained more than once a week, and that early progress comes from repeating a small number of movements often enough to get good at them. Any schedule satisfying those two is reasonable.

So take the advice as being about structure rather than about the number, and if you want a fourth day, add one — as an upper/lower split rather than as a body-part split.

For the resistance part, the minimum effective version is smaller than people assume: two sessions a week, twenty to thirty minutes, covering a squat pattern, a push, a pull and something for the hips.

That can be done at home with no equipment initially and it addresses the gap almost entirely. Given you have already built a daily habit that has lasted months, adding two short sessions is a far easier proposition for you than it is for most people starting from nothing.