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Low UPF diet - to think the experts weren’t lying?

382 replies

AusBoundDD · 06/05/2025 21:03

Nearly 6 months ago I made it my New Year’s resolution to start eating a low UPF diet in hopes of losing some weight for a once in a lifetime trip, alongside just being healthier in general. Honestly it has been life changing! I’ve lost nearly 10kg without really having to think about it - no restricting or anything like that and in general I just feel so much better. UPFs like crisps, ready meals, even basic supermarket bread don’t feel like ‘real’ food anymore and no longer appeal. On the occasion that I do choose to eat something UPF (which for me is no big deal, im not strict!) it just isn’t as enjoyable as it used to be. I’d choose some sourdough over a loaf of Hovis any day when previously I used to hate it! I feel much fuller + satisfied for longer and rarely get the urge to snack.

Obviously it has its downsides - much less convenience food so cooking takes longer (PITA when doing lunch/dinner prep after a long day at work!), ingredients are more expensive so my shopping bill has gone up but all in all it’s a decision I don’t regret. Honestly I think that this way of eating should be the future.

Anyone else feel this way?

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NattyTurtle59 · 08/05/2025 22:30

Jacarandill · 08/05/2025 15:09

So it didn’t work long term then…

Anyone see a pattern emerging?

I wasn't actually eating like that to lose weight, it was a pleasant side effect. Once my emotional issues were sorted out then I returned to normal eating, but still didn't return to my previous weight.

The point I was making is that it isn't eating UPFs which makes people gain weight, portion sizes have increased greatly and it doesn't actually matter what you are eating, it is the amount that you eat. I eat a fair number of UPFs, alongside lots of proper food, and my weight rarely increases - if it does I just eat a bit less and off it goes again. I never "diet", I eat whatever I want.

People overthink this stuff. Obviously we should be eating healthy food, but this insistence that UPFs are the sole cause of weight gain is simply a very convenient excuse!

Fizbosshoes · 08/05/2025 21:09

DancefloorAcrobatics · 08/05/2025 19:25

Let me explain it in layman's terms with a simple example:
100g of almonds have around 50g of fat . 100g of whole almonds = 575 calories.

100g of ground almonds = 610 calories.

Simply by processing/ grinding the almonds, you add calories.

Now, this is because because of the cell structure of almonds. In whole almonds, our bodies can not digest all the fat / calories that are associated with almonds, only about 90% of it.
If you grind (process) the almonds, you are breaking down the cell structure of the whole almonds. Making the fats more accessible to our bodies through digesting. Suddenly,99% of the fat can be absorbed by the body.

A little side effect is, that the undigestable part of the almonds are adding bulk/ fibre to our diet. Your body will work hard and burn some calories trying to digest all of the almonds without success.

On a small scale, it's irrelevant and has little effect. But if this happens meal after meal with a fraction of every food you eat, it will add up and lead to some weight loss.

I'm annoyed with myself for getting invested with this but.....
I usually have berries with nuts and Greek yoghurt for breakfast.
I recently bought chopped Brazil nuts thinking they would sprinkle further IYSWIM, and I would have less weight of nuts that way. (I don't want to get into the habit of weighing food again, unless for a recipe)
....but is chopping them considered processed, by your example? Will they have more cals per 100g in that form?

SnakesAndArrows · 08/05/2025 19:46

DancefloorAcrobatics · 08/05/2025 19:25

Let me explain it in layman's terms with a simple example:
100g of almonds have around 50g of fat . 100g of whole almonds = 575 calories.

100g of ground almonds = 610 calories.

Simply by processing/ grinding the almonds, you add calories.

Now, this is because because of the cell structure of almonds. In whole almonds, our bodies can not digest all the fat / calories that are associated with almonds, only about 90% of it.
If you grind (process) the almonds, you are breaking down the cell structure of the whole almonds. Making the fats more accessible to our bodies through digesting. Suddenly,99% of the fat can be absorbed by the body.

A little side effect is, that the undigestable part of the almonds are adding bulk/ fibre to our diet. Your body will work hard and burn some calories trying to digest all of the almonds without success.

On a small scale, it's irrelevant and has little effect. But if this happens meal after meal with a fraction of every food you eat, it will add up and lead to some weight loss.

How patronising you are. Yes, there is a food matrix effect that affects availability of calories for absorption to a small extent. A diet that encourages a fast gut transit time will also have an effect on absorption.

You cannot be suggesting, though, that a piece of sourdough bread that contains 100 calories is somehow less calorific than a piece of supermarket bread that contains 100 calories. A piece of fish that contains 100 calories is somehow less calorific than a piece of fake meat that contains 100 calories?

However, I know which I’d prefer to eat, and I know which is more nutritious. I just think there’s no need to wrap healthy eating messages up in pseudoscience.

Eat less, mostly plants, and move more.

DancefloorAcrobatics · 08/05/2025 19:25

SnakesAndArrows · 08/05/2025 16:22

I don’t know. I can’t find any evidence to support the idea that swapping UPF for non-UPF but still eating the same number of calories will result in weight loss, or vice versa.

Yes, junk food is junk and makes you crave and eat more junk, and emulsifiers and other artificial additives aren’t good for you at all, but calories are just calories, unless anyone can provide evidence to the contrary.

Let me explain it in layman's terms with a simple example:
100g of almonds have around 50g of fat . 100g of whole almonds = 575 calories.

100g of ground almonds = 610 calories.

Simply by processing/ grinding the almonds, you add calories.

Now, this is because because of the cell structure of almonds. In whole almonds, our bodies can not digest all the fat / calories that are associated with almonds, only about 90% of it.
If you grind (process) the almonds, you are breaking down the cell structure of the whole almonds. Making the fats more accessible to our bodies through digesting. Suddenly,99% of the fat can be absorbed by the body.

A little side effect is, that the undigestable part of the almonds are adding bulk/ fibre to our diet. Your body will work hard and burn some calories trying to digest all of the almonds without success.

On a small scale, it's irrelevant and has little effect. But if this happens meal after meal with a fraction of every food you eat, it will add up and lead to some weight loss.

BitOutOfPractice · 08/05/2025 19:04

OliveBranchesOut · 08/05/2025 16:03

You can buy tinned soup that has 300mls.

TBH tinned soup has zero nutrition compared to fresh soup or homemade.

Occasionally I buy cartons of fresh soup and they last for at least 2 servings.

I know that. I was just using it as an example of skewed portion sizes.

OddBoots · 08/05/2025 18:57

SnakesAndArrows · 08/05/2025 16:22

I don’t know. I can’t find any evidence to support the idea that swapping UPF for non-UPF but still eating the same number of calories will result in weight loss, or vice versa.

Yes, junk food is junk and makes you crave and eat more junk, and emulsifiers and other artificial additives aren’t good for you at all, but calories are just calories, unless anyone can provide evidence to the contrary.

I think you are right - it's just it is easier to not eat more calories than you need if you eat whole foods. There is something about the processing that makes many people want to eat much more.

mummytoonetryingfortwo · 08/05/2025 16:22

Of course they weren’t. We need to fuel our bodies.

SnakesAndArrows · 08/05/2025 16:22

OliveBranchesOut · 08/05/2025 16:05

Isn't the research the one that Chris Van Tulkeken looked into?

And he followed up the effects of UPF on the brain with researchers at UCH London.

Edited

I don’t know. I can’t find any evidence to support the idea that swapping UPF for non-UPF but still eating the same number of calories will result in weight loss, or vice versa.

Yes, junk food is junk and makes you crave and eat more junk, and emulsifiers and other artificial additives aren’t good for you at all, but calories are just calories, unless anyone can provide evidence to the contrary.

Comedycook · 08/05/2025 16:19

I don't doubt that upfs are bad for our health....but health and weight whilst being closely linked don't always match up. I've known several very thin people who have absolutely appalling diets... mainly upfs...they just don't eat much.

ChillyPanda · 08/05/2025 16:09

biochemist here who worked in a large international food company. RE UPFS there is peer reviewed published evidence that emulsifiers disrupt the gut bacteria and affect risks of bowel cancer and immunity /allergies

linked in here

https://www.healthline.com/health/food-nutrition/what-are-emulsifiers#uses

What Are Emulsifiers? And Are They Safe?

While there are many FDA-approved emulsifiers, European associations have marked them as being of possible concern. Let's look deeper:

https://www.healthline.com/health/food-nutrition/what-are-emulsifiers#uses

OliveBranchesOut · 08/05/2025 16:05

SnakesAndArrows · 08/05/2025 15:51

I don’t think you’re approaching this logically.

Your position is that eating UPF food will result in more weight gain than eating exactly the same number of calories of non-UPF food, I think? And therefore that switching from UPF to non-UPF whilst ingesting exactly the same number of calories will result in weight loss?

Assuming I have that right, then the previous posters’ anecdotes of weight loss by calorie reduction undermine your argument.

The fact that they may be to-yo dieting is irrelevant to your (apparent, thus far unsubstantiated) claim that UPF calories are somehow different in calorific value to non-UPF calories.

I’m not defending junk food, I’m not suggesting yo-yo dieting is good, I am certainly not denying that junk food is “addictive” and easier to over-eat.

I’d still quite like to see a study that backs up your claim, because I haven’t been able to find one.

Isn't the research the one that Chris Van Tulkeken looked into?

And he followed up the effects of UPF on the brain with researchers at UCH London.

OliveBranchesOut · 08/05/2025 16:03

BitOutOfPractice · 08/05/2025 12:57

Yes I think it’s your portions that are out, not the 70s video. I know, it’s a shock when you actually look at what portions are supposed to be. Like a tin of soup - the calories are always for half a tin. I mean, who eats half a tin of soup?!

Its only when I focus and really weigh and measure everything that I realise just how much my “normal portion” size has crept up!

You can buy tinned soup that has 300mls.

TBH tinned soup has zero nutrition compared to fresh soup or homemade.

Occasionally I buy cartons of fresh soup and they last for at least 2 servings.

SnakesAndArrows · 08/05/2025 15:51

Jacarandill · 08/05/2025 15:09

So it didn’t work long term then…

Anyone see a pattern emerging?

I don’t think you’re approaching this logically.

Your position is that eating UPF food will result in more weight gain than eating exactly the same number of calories of non-UPF food, I think? And therefore that switching from UPF to non-UPF whilst ingesting exactly the same number of calories will result in weight loss?

Assuming I have that right, then the previous posters’ anecdotes of weight loss by calorie reduction undermine your argument.

The fact that they may be to-yo dieting is irrelevant to your (apparent, thus far unsubstantiated) claim that UPF calories are somehow different in calorific value to non-UPF calories.

I’m not defending junk food, I’m not suggesting yo-yo dieting is good, I am certainly not denying that junk food is “addictive” and easier to over-eat.

I’d still quite like to see a study that backs up your claim, because I haven’t been able to find one.

Jacarandill · 08/05/2025 15:09

NattyTurtle59 · 08/05/2025 09:09

Same. I once lost quite a lot of weight and I was eating only UPFs, but mostly only at lunchtime with no breakfast or evening meal. I wouldn't do it again, but it certainly worked at the time.

So it didn’t work long term then…

Anyone see a pattern emerging?

Jacarandill · 08/05/2025 15:08

Pickingmyselfup · 08/05/2025 08:59

I've lost weight purely by calorie counting whilst still eating all kinds of stuff (bread, chocolate, ready meals) and drinking alcohol and diet coke.

I set myself a target based on my activity levels and stuck to it. In 2019 I went from being 65kg to 52kg and kept it off until 2020 when the world stopped. I ate too much, drank too much and didn't really exercise so I went back up to 60kg.

2022 I knuckled down, dropped the calories, upped the exercise and I'm down to 54/55kg. I go up when I don't track my calories because I simply eat too much. When I need to lose I retrack and I start to lose.

I'm not sure I'll ever be 50kg again like I was early 2020 but I'm choosing to eat more now because I need the calories for long distance running. I can no longer survive on 1300 calories anymore which is how I ended up getting to 50kg.

I'm not saying we shouldn't all make better choices, I'm just saying it isn't just UPF that makes people (me) fat.

So yo-yo dieting then…

CaveMum · 08/05/2025 14:47

PriOn1 · 08/05/2025 12:47

Many people who go low fat end up losing their gall bladder. It’s a recognised problem.

And the people who demonized fat were scientists paid by the sugar manufacturers. It’s been well documented.

So yes, science is skewed by money and politics. We’re currently living in an era when people are being mutilated and put on hormones for a lifetime because they are suffering from mental health problems. The man who popularized lobotomy was a doctor who won the Nobel Prize. Science does not exist in a vacuum which is why US medicine looks very different to what we get on the NHS in the UK.

To back this up, this is well worth reading. It's 9 years old but is about the same guy (Robert Lustig) that is in the podcast I linked to earlier.

The sugar conspiracy | Sugar | The Guardian

The sugar conspiracy | Ian Leslie

The Long Read: In 1972, a British scientist sounded the alarm that sugar – and not fat – was the greatest danger to our health. But his findings were ridiculed and his reputation ruined. How did the world’s top nutrition scientists get it so wrong for...

https://www.theguardian.com/society/2016/apr/07/the-sugar-conspiracy-robert-lustig-john-yudkin#:~:text=A%2090%2Dminute%20talk%20he,culpable%20for%20America%27s%20obesity%20epidemic.

BitOutOfPractice · 08/05/2025 12:57

Comedycook · 08/05/2025 11:41

Yes as a light lunch I might have something like that..but a main meal for my DH and ds, it would not go down well! To be honest perhaps that is how much we should be eating. When you look at what portion sizes are meant to be, it always surprises me how small they are. I sometimes buy those sachets of microwave rice for DH and ds....each sachet is apparently two portions but they eat one each....ds sometimes has two!

Yes I think it’s your portions that are out, not the 70s video. I know, it’s a shock when you actually look at what portions are supposed to be. Like a tin of soup - the calories are always for half a tin. I mean, who eats half a tin of soup?!

Its only when I focus and really weigh and measure everything that I realise just how much my “normal portion” size has crept up!

PriOn1 · 08/05/2025 12:47

TokyoKyoto · 08/05/2025 12:20

OK our experiences are different. I am of the same generation, but it was always obvious that high sugar wasn't a good diet. There was also a ton of emphasis at the time on high fibre and whole foods. Low fat is good.

And it wasn't necessarily experts saying sugar was fine. It was diet book writers - a very different demographic. But anyone who went, 'I can't have a fry up but these five bars of chocolate won't harm me' needed their head read.

Many people who go low fat end up losing their gall bladder. It’s a recognised problem.

And the people who demonized fat were scientists paid by the sugar manufacturers. It’s been well documented.

So yes, science is skewed by money and politics. We’re currently living in an era when people are being mutilated and put on hormones for a lifetime because they are suffering from mental health problems. The man who popularized lobotomy was a doctor who won the Nobel Prize. Science does not exist in a vacuum which is why US medicine looks very different to what we get on the NHS in the UK.

TokyoKyoto · 08/05/2025 12:25

The idea that experts never lie is problematic.

No, it isn't. They take what is the best evidence at any given time and work from that. I didn't mean they are always 100% correct.

It's so unproblematic that we hardly have any examples of experts lying. Experts being qualified, employed by the right institutions or bodies, etc, not YouTubers or that guy who left academia because they wouldn't take him seriously. Andrew Wakefield lied like a flatfish and that's been a massive, massive problem. I'm sure there are a handful of others. But by and large experts lose their reputations if they lie, which keep them employed.

TokyoKyoto · 08/05/2025 12:20

PriOn1 · 08/05/2025 12:14

They were. I am of the generation who followed the “experts” who sold the lie that fat was the enemy and sugar was fine.

I was marginally overweight when young. My mother suggested I cut down on carbs as that was what they’d always recommended when she was young.

I read up on the topic, which said it was all about counting calories and cutting out fat was best as that had the most calories. It’s still a very prevalent attitude. Most supermarkets are still full of low fat foods, often filled with sugar to make them more palatable.

All I ended up with was excess weight and gall bladder problems as I failed on diet after diet.

The idea that experts never lie is problematic. It’s very difficult as I’d still rather trust science to help me, but finding out which science is good and which is created with an agenda driven by money and not genuinely to find out facts to help people is very difficult.

OK our experiences are different. I am of the same generation, but it was always obvious that high sugar wasn't a good diet. There was also a ton of emphasis at the time on high fibre and whole foods. Low fat is good.

And it wasn't necessarily experts saying sugar was fine. It was diet book writers - a very different demographic. But anyone who went, 'I can't have a fry up but these five bars of chocolate won't harm me' needed their head read.

PriOn1 · 08/05/2025 12:14

TokyoKyoto · 07/05/2025 12:43

It worries me that you think the experts were lying. About basic nutrition 😲In general experts don't lie, they have checks and balances that prevent them from doing that. There's been a brilliant shift in rhetoric to cast doubt on experts, from people whose interests are served by the population being credulous about everything except what's told to us by experts. That's how we're politically in the state we're in.

Anyway YANBU of course food is better than semi-food or non-food.

They were. I am of the generation who followed the “experts” who sold the lie that fat was the enemy and sugar was fine.

I was marginally overweight when young. My mother suggested I cut down on carbs as that was what they’d always recommended when she was young.

I read up on the topic, which said it was all about counting calories and cutting out fat was best as that had the most calories. It’s still a very prevalent attitude. Most supermarkets are still full of low fat foods, often filled with sugar to make them more palatable.

All I ended up with was excess weight and gall bladder problems as I failed on diet after diet.

The idea that experts never lie is problematic. It’s very difficult as I’d still rather trust science to help me, but finding out which science is good and which is created with an agenda driven by money and not genuinely to find out facts to help people is very difficult.

LittleArithmetics · 08/05/2025 11:54

Comedycook · 08/05/2025 11:41

Yes as a light lunch I might have something like that..but a main meal for my DH and ds, it would not go down well! To be honest perhaps that is how much we should be eating. When you look at what portion sizes are meant to be, it always surprises me how small they are. I sometimes buy those sachets of microwave rice for DH and ds....each sachet is apparently two portions but they eat one each....ds sometimes has two!

We'd have the frittata for dinner with slightly more substantial veg on the side. Admittedly a lighter dinner than some, but it works. We also split the rice pouches between 2 of us (with a good amount of curry/whatever the main is).

Comedycook · 08/05/2025 11:41

LittleArithmetics · 08/05/2025 11:30

The phrasing 'a quarter of an omelette' sounds very mean, but I make a frittata using 7 eggs typically, and cut it into quarters. Maybe not wildly different, depending on what's in the omelette.

Yes as a light lunch I might have something like that..but a main meal for my DH and ds, it would not go down well! To be honest perhaps that is how much we should be eating. When you look at what portion sizes are meant to be, it always surprises me how small they are. I sometimes buy those sachets of microwave rice for DH and ds....each sachet is apparently two portions but they eat one each....ds sometimes has two!

LittleArithmetics · 08/05/2025 11:30

Comedycook · 08/05/2025 07:57

In terms of weight I think portion size is the main factor. I watched on YouTube recently a cooking video from the 1970s. They made an omelette and used six eggs and said how should cut it into quarters and everyone gets a quarter with some salad. If I served up a quarter of an omelette to my DH and DC, they'd be up in arms!

The phrasing 'a quarter of an omelette' sounds very mean, but I make a frittata using 7 eggs typically, and cut it into quarters. Maybe not wildly different, depending on what's in the omelette.

NattyTurtle59 · 08/05/2025 09:09

Pickingmyselfup · 08/05/2025 08:59

I've lost weight purely by calorie counting whilst still eating all kinds of stuff (bread, chocolate, ready meals) and drinking alcohol and diet coke.

I set myself a target based on my activity levels and stuck to it. In 2019 I went from being 65kg to 52kg and kept it off until 2020 when the world stopped. I ate too much, drank too much and didn't really exercise so I went back up to 60kg.

2022 I knuckled down, dropped the calories, upped the exercise and I'm down to 54/55kg. I go up when I don't track my calories because I simply eat too much. When I need to lose I retrack and I start to lose.

I'm not sure I'll ever be 50kg again like I was early 2020 but I'm choosing to eat more now because I need the calories for long distance running. I can no longer survive on 1300 calories anymore which is how I ended up getting to 50kg.

I'm not saying we shouldn't all make better choices, I'm just saying it isn't just UPF that makes people (me) fat.

Same. I once lost quite a lot of weight and I was eating only UPFs, but mostly only at lunchtime with no breakfast or evening meal. I wouldn't do it again, but it certainly worked at the time.

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