The NYTimes just ran an article about nutrition myths. One of them was about calories in - calories out.

“ Ultraprocessed foods — such as refined starchy snacks, cereals, crackers, energy bars, baked goods, sodas and sweets — can be particularly harmful for weight gain, as they are rapidly digested and flood the bloodstream with glucose, fructose and amino acids, which are converted to fat by the liver.”

Your body will only store surplus fat long-term if you consume enough calories to maintain the surplus. Otherwise your body makes fat from the sugary sweets, but then later converts it back and burns it when you need energy.

The real “myth” of calories in = calories out is that it’s possible to do it by feel. It takes a lot of work and math, like spreadsheet-level, to actually track calories in and out. So even though it is physically true as a concept, it’s not a good weight management strategy for most people.

Sugary snacks don’t make you feel very full for their caloric content. So unless you’re literally writing down the caloric information on the wrapper and comparing it to your total daily activity, it’s easy to overeat.

> The real “myth” of calories in = calories out is that it’s possible to do it by feel. It takes a lot of work and math, like spreadsheet-level, to actually track calories in and out. So even though it is physically true as a concept, it’s not a good weight management strategy for most people.

The real myth is that you can track calories in and calories out.

How do you measure how many calories your body absorbs from the food you eat?

How do you measure your calories out, particularly your resting metabolic rate?

Here's a hint -- the body changes its resting metabolic rate in response to calories in! Probably! Unless you eat junk food, and then maybe it doesn't!

You don't need to know these rates, you just need to have a point of reference from which you can change according to your weight loss goals. Not losing enough weight for the given caloric intake? Then just dial it back and reassess.

You track calories in by making all your food and weighing everything you eat.

In practise you don't need to track the out because it doesn't change much per day. It's not easy to burn 200 calories but it's easy to consume them. That's why it's common to hear that weight loss happens in the kitchen.

It is absolutely possible to do it. Thousands of athletes and artists who depend on their weight professionally do it. Here’s one example:

https://youtu.be/5356zt0JiDY

It does require work to understand your particular body, and discipline to do it consistently. Which is again, why it is not a good technique for most people. Most people don’t have the time, motivation, or really the need to do what this woman (in the video) is doing.

Tracking actually makes this super simple to account for.

Apps like Macrofactor do it for you. You just track what you eat and your weight.

It’s really common for the argument against CICO to be that it’s not perfect, measuring input and measuring output seem hard, and metabolism is elastic, and people are different. Those things are all true, but using CICO in practice to lose weight actually works, and it’s quite effective for most people, as long as you actually do it. CICO is how bodybuilding and modeling works. ;) The hardest part isn’t the measuring. The hardest part is making it a habit.

One secret about using CICO is that you do not need to know the gut absorption rate! You just need to track the calories before absorption, the numbers printed on the box. Easy these days with a smartphone app. The measurement does not need to be perfect at all. It only has to be decent on average. You can have variable accuracy of 25% on any given food and still get well under 10% on average for a week. It doesn’t matter if there’s a bias either, if you track your weight. The reason absorption and bias don’t matter is because you’re doing science with a black-box (your body). Measure the known input, monitor the output. Do it for a long time and you’ll find the maintenance input. Track input above that and verify mass gain, track below and verify loss. The maintenance value you come up with will “absorb” and bias, and gut calorie conversion rate, and other inaccuracies.

Measuring output is easy with a heart rate monitor. Changing metabolism we already discussed, but important to know that the range of elasticity is like around 15%, and in practice for any give person may be lower. It’s not some massive factor you can’t predict, it’s within a narrow enough range for the majority of people, statistically, that you don’t need to worry too much. And it will be accounted for if you track calories and weight over a long enough time frame.

Smartwatch can give a reasonable approximation of calories out

Here's a Harvard fluff piece making the same "myth" claim: https://www.health.harvard.edu/staying-healthy/stop-counting....

And here is a recent peer-reviewed article that summarizes the debate: Ludwig, D. S., Apovian, C. M., Aronne, L. J., Astrup, A., Cantley, L. C., Ebbeling, C. B., ... & Friedman, M. I. (2022). Competing paradigms of obesity pathogenesis: energy balance versus carbohydrate-insulin models. European journal of clinical nutrition, 76(9), 1209-1221.

I guarantee the skinny long distance runners and pro cyclists you see all pound far more ultra processed pure sugar than anyone fat you know. It's literally the only way to take in calories fast enough to keep exercising at an intense level for hours.

Regardless of diet you will lose weight if you eat fewer calories than your body is burning. It will be harder if you eat junk food, but quite possible.

if your weight didn't change, most likely you were eating at maintenance. The fact that you have a surplus every now and then won't change your body composition. Consistency matters a lot with regards to human weight.

To add to what someone else said, you probably ate below your threshold to be able to maintain your weight. You can't guess this, the only way to get an accurate ESTIMATE on how much you actually ate in calories is to measure. Even pros over/under estimate what they eat in terms of calories

> I’ve never believed this — only because my weight is so consistent and my eating is not.

That's only one side of the equation.

It is a basically proven fact (and largely implied by physics) that `calorie intake - expenditure = net weight change`. That is pretty much beyond dispute.

It is also true that some things affect expenditure, and it seems likely that most people have a "set point" that your body attempts to return to. This is also almost certainly changeable, as people have managed to change it in the past. (And this is less surely true than other things known.)

So yes, it's entirely possible to eat "inconsistently" and not have net weight change, your body is probably subconciously causing you to eat less after you eat large meals, and vice versa. Or possibly causing you to expend more energy after large meals.

How easily one can lose weight seems to be more than calories in and calories out. Women with PCOS struggle mightily with weight. Having said that, I'm sure if you put a person in a box for 21 days without food you will observe a net weight change, but I'm sure the speed at which weightloss occurs or is observed will include other factors beyond calories in and out.

The Alone show is pretty interesting as an example of what could happen being in a box with no food. Men and women of all shapes and sizes go into that show and they all just slough off weight, like over a pound a day sometimes, and struggle bringing in enough food for their body to not starve. Many are medically discharged from the show if they lose too much weight too fast where it puts their internal organs at risk.

There's a psychological component to sticking to a diet for sure, but no, a calorie deficit of the same amount will result in the same weight loss rate.

People locked in a box will not be able to cheat and will demonstrate this.

Could also be that the incredibly complex digestive system isn't just a food mulcher but is capable of moderating caloric intake based on any number of parameters.

Eat a high-fat meal or a can of Pringles with Orlistat, then you'll have an idea of what happens if your digestive system fails to extract calories from what you eat. Trust me, you'll know.

No, our digestive tracts are extremely good at extracting any and all usable calories from our food.

100% of the time, when someone makes this claim, they are mis-estimating either their intake or expenditure, or not tracking for a long enough time period to escape the error bars inherent in daily hydration variance.

Best I can do is 95%.

It's pretty easy to come up with ways the body wouldn't take up calories. I and everyone here has had diarrhea for example. I've eaten 5k calories on a sedentary day with no impact on weight as well tho it's hard to account for water without a strict accounting.

What's harder to refute is the loss of weight due to calorie restriction which is mostly physics. This is what the gp is talking about.

FWIW, I thought the same thing about my body for a long time, most of my life. I have usually been slightly overweight, a bit chubby, but pretty active in terms of sports and outdoor activities and exercise. Then I tried counting calories, and it totally worked, and I realized I’d forever been mentally resisting the idea of budgeting my food. My theory is that my regulating system isn’t gut absorption, it’s just how full I feel, and the threshold where I choose to stop eating, on average. My threshold is slightly higher than what I need to be skinny, and counting calories taught me what it feels like to eat the correct amount for me, which leaves me just a tiny bit hungry. I’m not currently counting calories, and I’m gaining weight little by little. Hard to say what happens when you have a one-off over-eating meal that’s insanely high calorie. You probably don’t absorb all the calories of an abnormally high-calorie meal, but that may change if you always eat a high calorie meal. Under-eating on occasion might have a different effect than over-eating. But yeah, it is easy to measure, if you can bring yourself to do it. I developed mental tricks so that it was easier to count calories and be fine being a little hungry, I feel like it’s important to avoid framing it as a self-control problem, or as overcoming hunger, and find ways to actually want to stick to the budget.

I'm not sure what to tell you besides it's true. I did crossfit for years without monitoring my diet and was always disappointed with how little I felt my body changed. I monitored my caloric intake for two months and was shocked to see how much of a difference it made.

Also, weight gain/loss should be measured on a weekly scale rather than daily. You might feel like your eating isn't consistent but it could be on a weekly-basis. For example, you might barely eat one day but eat 3500 calories the next. That seems like inconsistent dieting but in actuality, they average each other out.

Yeah, day by day it's not important - how full your bowels and bladder or how much water you're retaining are going to effect you more than your 24 hours of weight loss. It's a waste to sample that often and can be discouraging for no reason. It's really week by week and using that data to calculate a trend.

Availability of the calories varies substantially, and day-to-day water retained varies on the order of a few lbs easily.

Just consider how much flatulence varies meal-to-meal, that's largely produced by calories guests living in your gut "burned" instead of you.

The trouble is it's a complex ecosystem hosting many lives, controlled by hormonal knobs affecting behavior/activity-level and energy storage, and the makeup of the food hugely affects how much is absorbed and at what rate.

Everyone knows first-hand when over-eating a massive meal of hard to digest foods there's a substantial amount of energy deposited in the toilet... And wild pigs / pet dogs don't get excited about eating human feces for lack of caloric value.

It's just an upper bound, nothing more.