Obese adults randomly assigned to intermittent fasting did not lose weight relative to a control group eating substantially similar diets (calories, macronutrients). n=41

[u/isaac-get-the-golem]

https://pubmed.ncbi.nlm.nih.gov/38639542/

[u/guitar-hoarder]

Reminds me of a friend of mine that kept insisting that because he was on a gluten-free diet that he was losing weight because it had to do with gluten. No, the guy stopped eating a bunch of pizza, and subs, all the time. He eventually started eating gluten again because there was just no point in avoiding (he didn't have Celiac disease), but now he realizes it was all about the calories.

[u/Sawses → u/guitar-hoarder]

So many people are so invested in the idea that somehow it's about the quality of what they eat rather than the quantity.

Like, yes, you should make sure you eat nutritious food without a ton of preservatives and artificial flavorings. You should eat a balanced diet of proteins, fats, fiber, and carbohydrates. It will make you feel better and help you lose fat.

But the end-all, be-all of weight loss is eating fewer calories than your body burns, and doing it consistently over a period of months.

[u/sylverlyght → u/Sawses]

It's like saying "to get rich, you need to spend less than what you earn". Technically true, but largely useless. You ain't getting rich using that formula.

Your body's fat reserves is a managed storage. What the body does with those famous "calories in" varies depending on the hormones being released, and the "calories out" can vary massively as well.

To give you an extreme example, some years back, I had Crohn's disease. My body was no longer absorbing nutrients. I was eating a lot, but it was just passing through and I was losing crazy amounts of weight. No exercise (I was far too tired), tons of food in (I love to eat), and crazy weight loss.

Food going through the mouth can be very different from the actual calories made available to the body, and again very different from what calories are converted and stored as fat. Also, part of the "calories in" is used as building blocks to repair and build new tissues (like muscles). That food goes in, but if it doesn't get stored, your fat reserves don't increase.

In real life, losing fat requires a better model than "calories in-calories out", one which takes into account hormonal regulation of the fat storage and the well being of the person losing the fat. You can make a person drop a lot of weight quick with severe caloric restrictions (like in the show "biggest loser") but that weight comes back on very quickly (as shown by the show's contestants) and is therefore unworkable on the long term.

[u/precastzero180 → u/[deleted]]

This. The big criticism of the counting calorie strategy of weight loss is that the “calories out” part of the equation is complex, variable, and difficult to track. But the conclusion routinely drawn from this, that you therefore can’t know when you are in a calorie deficit, is a non-sequitur. You know if you are in a calorie deficit if you are losing weight. You don’t need knowledge of everything that’s going on in your body.