[jghn]

Not just out, both directions can be tricky to measure. It is hard to say for certain how many potential kcal you're consuming are actually absorbed by the body. If you see whole corn kernels in the toilet, those kcal didn't count :)

But yes. CICO is and always has been absolutely true. People are just overly reductive in how they measure both sides, and then claim that CICO is garbage.

[nahkoots]

Often, the whole kernels you see in the toilet aren't actually filled with corn.

[swat535]

In my experience, the most reliable way to understand your body's calorie needs is through consistent measurement:

1. Log everything you eat each day.

2. Weigh yourself first thing the next morning, before eating.

3. Track the trend (did you gain, lose, or maintain?)

Over time, clear patterns emerge. You start to see exactly how your intake maps to weight changes, and you can fine-tune accordingly. It’s not guesswork, it’s feedback.

What surprised me most was how little food I actually needed. Even with regular strength training, a modest surplus was enough to support muscle growth.

[themaninthedark]

From the fine article: >"People often lose muscle and gain body fat as they age—even when their body weight remains the same,"

[mariusor]

Aren't calorie numbers on foods just made up numbers anyway? I'm no expert but I'm pretty sure that a body's method of metabolizing food is not the same as oxygen burning it. They might offer a standardized number, and a basis for comparison, but other than that it's not reflective of anybody's reality.

[dzhiurgis]

You need to get orders of magnitude right at first. I find keeping a punned tab with any AI works pretty well. Drop 5 words with every meal or snack and thats it.

[ses1984]

My brother: those kernels are filled with poop.

It’s ok to assume that you absorb 100% of what you eat, unless you see evidence to the contrary, and no corn kernel poop doesn’t count. Frequent diarrhea, weight loss, skin rash, and basically any symptom of vitamin or mineral deficiency.

[DebtDeflation]

>It’s ok to assume that you absorb 100% of what you eat

That's not really true. If you've ever done the keto diet, you know that your body expels unburned ketones through your breath, sweat, and urine. Protein can be used to repair structures rather than burned or stored for energy.

There's also something called the "thermic effect of feeding". Your body requires more energy to process protein (20-30% of calories consumed) than it does carbs (5-10%) than it does fats (0-3%).

[codingdave]

> you know that your body expels unburned ketones

In other words, "calories out".

[anonymars]

Great, but parent is responding to

> It’s ok to assume that you absorb 100% of what you eat

[ses1984]

It didn’t get converted to ketones and expelled in your poop.

Your gut absorbed it. That is literally what digestive absorption is about. Expelling ketones is not digestive malabsorption.

[anonymars]

There are many ways for food to not be 100% absorbed, which I think can most easily be demonstrated by eating a bag of nuts and waiting a day or two

I don't think it's unreasonable to think that different bodies absorb food in different ways (or proportions), particularly given what we've seen about the gut microbiome

Apparently even just changing the time of food intake can affect obesity (in rats) if this study is to be believed: https://pubmed.ncbi.nlm.nih.gov/22608008/

In response to, "but those are rats", I think it's a lot easier to cast doubt on "100% of food is always absorbed" vs "I don't think that always holds true"

I mean, heck: if there are no residual calories in human waste, how can it burn?

[alecst]

Here's evidence to the contrary:

https://www.latimes.com/science/story/2020-02-04/calorie-cou...

[ses1984]

It’s not like almonds have x calories for a certain group and y calories for another.

Being wrong about the number of calories in almonds doesn’t count as evidence that skinny people are skinny because they poop out undigested calories.

Also, I’m not saying digestive malabsorption is impossible, just that you shouldn’t assume it unless you have strong evidence to the contrary that doesn’t have another simpler explanation.