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[dupe] Ultra-Processed Diets Cause Excess Calorie Intakeand Weight Gain: Randomized [pdf] (cell.com)
34 points by nabla9 32 days ago | hide | past | web | favorite | 16 comments

"[Dupe]" doesn't seem appropriate when so much time has elapsed that we can't even comment.

On HN the turnover is about a year: https://news.ycombinator.com/newsfaq.html. If it were as short as two weeks, which is the commenting window, the same few hot stories would get rediscussed over and over.

I think it's more likely that this conclusion is true than that it's false.

However, the fine article says: "We admitted 10 male and 10 female weight-stable adults".

That is a ridiculously small population to start with. Yes, yes, I know it's expensive to have many participants, but part of the broader problem in today's science is that too many experiments are accepted broadly even though they are based on tiny sample sizes. This is an excellent justification for conducting a larger study, not a conclusion in itself.

From Table 3 Fasting Blood Measurement Baseline:

> PYY (pg/mL) 25.1 ± 1.9 34.3 ± 1.9

PYY is a hormone which regulates feeding in humans. From another study:

> Several lines of evidence suggest that low circulating PYY concentrations predispose towards the development and or maintenance of obesity. [0]

A highly processed diet reduces the levels of PYY in the blood by around 30-40%. That's pretty damning evidence.

[0] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2670018/

> Our study was not designed to identify the cause of the observed differences in energy intake.

Would be great to see a factor breakdown (obviously hard). I can see several reasons why processed food leads to this result: chemically better tasting (optimal flavor blast + salt/falt), mentally better tasting (i.e. comfort food), or some deeper gut reasons?

because this then sets the agenda for how we fix this problem.

another thing could be that it's just calorically dense if ad libitum is encouraging people to eat until they're tastes are satiated

"While we attempted to match several nutritional parameters between the diets, the ultra-processed versus unprocessed meals differed substantially in the proportion of added to total sugar (54% versus 1%, respectively)."

It's an interesting study, but I would still like to see more strict calorie for calorie, and macro for macro match.

By allowing the participants to eat freely and by having so much more sugar in the processed diet, all this really shows is that processed diet was leaving participants more hungry so they ate more.

They appear to have matched sugar for sugar between the diets, with the difference being that the processed diet had much more added sugar.

Letting the participants eat ad libitum was a deliberate part of the study design, which was intended to develop information about whether an ultra-processed diet encourages eating more in terms of food energy than an unprocessed diet does. I'd be curious to know how you would modify the study design to achieve that end while also eliminating ad libitum intake.

>> "all this really shows is that processed diet was leaving participants more hungry so they ate more. "

This is 99.9% of the reason why people are overweight.

Every biological being eats until they're full(the body stops sending hunger signals). this is true for human, as it is ducks, monkeys, dogs or pretty much any other animal. For many, eating junk food/processed foods, breaks this satiety mechanism (and not just in the short run, there may be long term effects that prevent people from going back to normal).

Not being hungry, having satiety is the holy grail of weight management. Unfortunately, we don't have the means to produce satiety without calories. Yes, fiber/protein/micronutrients densities do help a little, but it does not help enough.

And there hasn't been enough studies on it. Other than the Holtz studies I haven't found much done on this subject.

There are a number of prescription weight loss medications that increase the feeling of satiety. Maybe you meant that we haven't found a way to do it without side effects?


> processed diet was leaving participants more hungry so they ate more.

That sounds compatible with the "Ultra-Processed Diets Cause Excess Calorie Intake and Weight Gain" conclusion in my opinion.

I wasn't saying the conclusion was wrong, just perhaps too obvious.

Eating whole foods is healthier than eating packaged foods is pretty intuitive at this point.

In a study that did not allow free eating, we could have gone further to find out if a 100% controlled ultra processed diet, was still worse for you the subject that a calorie matched diet based on whole foods.

[Sugar is already a known cause of obesity](https://youtu.be/dBnniua6-oM). The food being processed is irrelevant other than the important observation that processed foods tend to have lots of added sugar.

> The food being processed is irrelevant

It's absolutely relevant, considering the conclusion of the study was that people feel less satiated after eating a diet high in processed food, thus continue to eat and consume more calories.

My point is that the conclusion is specious.

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