There is ONE way to lean.
Calorie defecit.
This is a topic I love.
The problem with the whole calorie deficit way of thinking is that the human body doesn't use calories for metabolic purposes.
I'll explain.
So a calorie is a measure of heat energy released when burning food in a bomb calorimeter.
Great.
Except for the fact that the human body cannot run on heat energy.
Now when I say this on Threads I always get some guy saying "thermodynamics thoughhhhhh."
It happens pretty much every time lol.
And their point would be right...
If the human body was a CLOSED thermodynamic system.
It is not.
We regularly exchange mass in the environment.
Plus how do you even track calories when the government allows food companies to be +/-20% out from the actual amount of heat energy?
What about the thermogenic effect of food as well?
The reality is you can't.
It's just an awful thing to even attempt.
So if we can't use calories then what do we do instead?
The simple answer is the human body has extremely potent hunger signals IF not poisoned by dietary carbohydrates.
The long answer is.
We have two essential types:
Fat and protein.
Carbohydrates are not required as your body is perfectly capable of making the required glucose from gluconeogenesis.
If you do not eat carbohydrates your body will release ghrelin when you're hungry and leptin when you're full.
All this boils down to eat when you are hungry and stop when you are full.
It really is that simple.
Throw in a 24-72 water fast every now and then for stem cell release and autophagy.
Carbs mess that signalling system up big time so that's why you can eat a pack of Doritos and feel hungry in 2~ hours.
Your body will over time reset to your genetic baseline of body fat%.
There is really no need to track anything.
Some body fat is needed for insulation and hormone production.
This doesn't even talk about systemic inflammation caused by constant randle cycle activation but I'm trying to keep this simple.
Btw the only exercise humans are designed for is high intensity exercise.
HIT has the added benefit of cardio as well so there is zero reason to do cardio itself for health/fitness purposes.
Long endurance stuff tends to hypertrophy the heart overtime but that's a discussion for another day.
TLDR: Fat + protein = genetic baseline of body fat %. HIT for muscle hypertrophy purposes and health. Calorie tracking is not needed.
PS: Avoid seed oils like the plague.