How does a slow metabolism break the laws of physics and thermodynamics, then? If you don't consume massive amounts of calories, where exactly is your body creating excess fat and energy stores from?
Energy cannot be created or destroyed. If you think a human body can magically create fat from nothing you need to go back to high school physics class.
Respectfully, you only know half of what you are talking about. Of course you can’t violate the basic laws of thermodynamics. And fat is stored energy, that is a fact. So energy in equals energy out. But we can’t easily measure all of the energy out part of the equation. Nor can we totally accurate at the energy in part for each individual.
Now what we are referring to as “metabolism” here at least, is the energy required to do the things our body needs to do to stay alive. Some bodies are very good at conserving that energy “ie lower metabolic rate”. Others are not, so more energy is “wasted” doing the same breathing/ heart beating, digesting, thinking etc. This energy expenditure is quite variable. An extreme example might be in people with major metabolic issues, like low thyroid levels, who will gain more weight than normal, even
With the same energy intake. Which is also the case for how much energy we attribute to certain activities, we arbitrarily say that for a given body weight, running a mile burns x number of calories, while there is a lot of variability on how many calories individuals of the same weight will actually burn. Furthermore some foods (Eg amino acids from protein) can be used as energy OR to build tissue in our bodies. Differences in these pathways could potentially lead to differences in fat storage. Furthermore, we know certain food have X number of calories. But that number is basically derived from how much energy would be released if you actually burned that food
. How much energy that is absorbed, not only depends on how much is eaten, but how much is actually digested and absorbed. And how much energy digestion and absorption uses up! So yes energy in = energy out, but be only have a crude estimate of either.
Differences in energy intake (ie eating) and expenditure due to physical activity cannot alone account for differences in body weight / fat stores in individuals. In fact calorie deprivation can actually lead to slowing of metabolism, to preserve energy stores. There is a whole hormonal system in the body just to manage energy storage in fat. Overeating with time can change the brain’s signals that manage energy intake (ie hunger and fullness). And just like every physiological system in the body, there is tremendous variation between individuals in how it works.
Like a car, if you drive at a certain optimal speed, (Eg 90-100 km)you will get good gas mileage. But the same car will burn way more gas if it is driven at an inefficient speed. The car is travelling the same distance, but burning more gas? Why? It’s the same amount of work (going from A to B) no? It’s because at certain conditions, more energy is consumed (ie wasted as heat) than in the optimal conditions.