Who cares if you have the slowest or fastest metabolism in the world. If you consistently eat a caloric surplus/deficit the end result is the same. People sometimes blame metabolism for being skinny or fat and I just don’t understand its relevance.
Edit: for those who don’t know CICO is Calories In. Calories out. Just means you calculate your BMR and TDEE and then adjust your caloric intake to match your goals.
In: Biology
The “CO” / “calories out” is tied to how much energy you have. People with a hyper-active thyroid constantly bounce off the walls through the whole day.
There’s more health concerns if your thyroid is fucked up though. So you really kinda want that one to be normal. Talk to your doctor if you’re always out of energy or if you just can’t ever seem to sleep. Most people who blame “their metabolism” are just looking for an excuse though.
The “calories out” portion of equation that is in your control isn’t much. Most of the calories you consume are spent keeping you alive and not spent in your muscles.
If you have weight issues, it’s almost entirely a matter of not eating so damn much.
The variance between maximum and minimum calories burned per day for the a human is massive. It changes based on metabolic rate, weight, and other genetic factors.
After testing, for example, I burned 1800 calories per day at rest, and my brother burned 1650 calories at rest, while weighing the same amount. We’re interested in weird data, so we paid to have the test done when we weighed 210 pounds just out of curiosity.
150 calories might not seem like much, but it is absolutely the difference between a caloric deficit and a caloric surplus. He would gain weight while eating the exact same diet that I was losing weight on.
Don’t get me wrong; running a caloric deficit is going to make you lose weight, period, end of story. But if you don’t know your basal metabolic rate, you can’t know for certain that you’re eating a caloric deficit.That means if you don’t pay real goddamn money to figure out your basal metabolic rate, you don’t actually know what it is, because it’s different for everybody. You can **guess**, but you can’t be certain.
Metabolism is the main contributor to the “CO” portion of “CICO”. The faster your metabolism, the more you can eat without gaining weight. In a world where we’re inundated with huge portion sizes and high-calorie foods, having a fast metabolism can make it much easier, psychologically-speaking, to lose weight.
Metabolism affects CICO.
If you’re a young, mid 20s male, you have a higher metabolism than a 50 year old post-menopausal female. So the CICO calculation is different for each.
If you have PCOS, your metabolism and therefore your CICO calculation will be different from a woman of the same age who doesn’t have PCOS.
CICO depends on your CO differential which is entirely dependent on your metabolism.
calories were originally calculated by burning the material in an isolated chamber to measure its energy output as heat. a raw piece of meat would have the same calories as the same piece of meat prepared as a steak, but the energy in the cooked version is more available for our bodies to absorb.
some people have higher/lower metabolisms, as well as different digestive efficiencies. my friend can eat a truckload of fast food and lose weight, since he has a super high metabolism as well as a poor digestive system, as he would pretty much shit all the food he ate out whole within a couple of hours and have 3+ bowel movements a day.
there are also cultures who eat 1000+ calories a day of coconut oil (their main cooking oil) but have generally low rates of obesity, so CICO is not as straightforward as it seems
example of extremes: metabolic rate of zero means every calorie is surplus
alternate extreme: a “miracle weight loss” drug in the 1930’s or so called dinitrophenol would increase the metabolic rate so that your body would basically act like it was in a state of exercise as a baseline, and you would send calories out at an excessive rate without physical exercise. heat is the product.
super interesting read, i left out a lot of detail that i think people would want to expand on
Because everyone’s body burns different amounts of kcals at rest.
If you have 2 people eating 2000kcals a day one can be in a calorie surplus while the other can be in a calorie deficit. Resulting in one person gaining weight and the other one loosing weight.
If you have a fast metabolism you burn more kcals at rest. If you burn more kcals over the day you can obviously also eat more kcals over the day.
So for someone with a slow metabolism CICO is still true, it’s just that they need to eat *even less* because they don’t burn that many kcals at rest over the day
TLDR: you need to know what your baseline is ie. your metabolism to calculate what a calorie deficit actually is
Stuff like BMI are just estimations, they aren’t super accurate
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