Rewilding: putting the system back in conditions it recognizes

They are not a route back to a lower defended weight; none of the six has been shown to move it.C-III-12 The rest of Part III makes the case that appetite defends the range forcefully, that the defense is asymmetric, and that even a year spent at a much lower weight did not install a new setting. None of that is undone by sleeping better.

It is more useful to take them for what they are: the conditions in which the regulatory system runs. The distinction matters. Getting them right does not reset anything. Getting them wrong makes everything else harder, and several of them are the difference between losing weight and losing muscle.

This is the strongest of the six. During calorie restriction, a substantial share of what comes off is lean tissue, and exercise training, resistance work in particular, is what holds on to it.C-III-13e The wording matters: in an energy deficit, resistance training preserves lean mass rather than building it. It is also the lever that matters most if you are taking a GLP-1.C-IV-08

Most of the physical activity that shows up in daily energy expenditure is not formal training but walking, standing, and fidgeting, the accumulated cost of not sitting still.C-III-13c

This is not a rounding error. Non-exercise movement accounts for a meaningful share of what the body spends in a day, and it is the part of expenditure most easily engineered out of a modern life.C-III-13c

In most studies, shortened sleep is associated with increased appetite and energy intake. The classic experiment found that curtailing sleep lowered leptin, raised ghrelin, and increased hunger, which is to say the same two hormones moving in the same two directions as they do after weight loss. In other words, short sleep reproduces part of the hormonal picture that follows a diet.C-III-13a

Importantly, the effect is not uniform. At least one controlled study found that severe restriction suppressed appetite rather than raising it, so the direction of the effect appears to depend on how much sleep is lost.C-III-13a

Higher-fiber eating is associated with greater satiety and with modest effects on body weight, where modest means modest, and the effect varies substantially by type of fiber.C-III-13d Given that appetite has been estimated to rise by roughly 100 calories a day for every kilogram lost, that is a small offset.

Diet changes the gut microbiome quickly and measurably. In one randomized trial, a diet high in fermented foods increased microbiota diversity and lowered markers of inflammation.C-III-13g

What this shows is that diet changes the microbiome. It does not show that changing the microbiome causes weight loss.

This is where the popular version and the evidence have come apart, which is why it is last on the list. Time-restricted eating does produce weight loss; meta-analyses put it broadly comparable to continuous calorie restriction. What has not been established is that the timing itself does the work, independently of the reduced intake that a shorter eating window tends to produce.C-III-13b

In practical terms, if a narrower eating window helps you eat less, it is a useful tool. If the hope is that the clock has a metabolic effect of its own on top of that, the evidence is not there yet.

Taken together, the six are not a route back to a lower defended weight. They change the conditions in which the regulatory system operates, they determine how much of a given loss comes out of muscle rather than fat, and in the cohorts that have been observed, sustained activity is what maintenance looks like in practice.

That leaves the question Part III has been building toward: if effort within these conditions still loses to the defense over time, what acts on the system itself. That is the subject of Part IV.