It's not. Human body can't create energy out of nothing, but it can vary the consumption of energy in a wide range which is very similar in terms of externally observable effects.
It's a common story when people start to eat 20% less, continue the same lifestyle and lose exactly zero weight as the result. Their body didn't create 20% of energy out of nothing but it just started to waste less energy as body heat.
They have literally done studies showing that this is a naive take. You might lose weight, but the literal moment you consume more calories your body stores every stray calorie it can and it battles you about loses weight every moment. Your body will save calories to the point of discomfort and ill health. The impacts of extreme calorie deficits last for extremely long times and bias your body towards weight gain.
The body is more like a thermostat system. Environmental effects can convince your body to move the temperature/weight up or down, but for both weight gain and weight loss is a battle. Your body tries to maintain it's understood ideal weight. Your body if given a chance and you haven't convinced it to change the thermostat setting, will immediately do all it can to gain/loose weight. This is why crash diets never work. It takes sustained effort to convince your body that it's wrong about your initial weight.
How are you measuring energy out, such that it can directly influence decisions on how much energy you should be deciding to take in? I promise you: Your methodology is inaccurate.
Very bad take. What if our bodies adjusts the burn rate based on when we eat when we exercise? if that is true you can potentially eat more and lose more weight.