This is a really great video and definitely something anyone should watch and understand if they’re considering trying keto or sugar fasting.

In the video, Nick Norwitz explains that both high-carb, low-protein (sugar fasting) and high-fat, low-protein (keto) diets elevate FGF21, which is the hormone responsible for increasing fat metabolism by raising energy expenditure. He also notes that genetic variants in FGF21 are extremely common—present in about 44% of people. If you have one of these variants, your FGF21 levels may not increase as expected on either diet, which means you might not experience the same rise in energy expenditure—and could even gain weight.

So why does he only offer caution about the sugar diet? That seems incredibly biased. I believe the same level of caution should be applied to keto as well, especially since, by his own explanation, the mechanism behind weight loss and increased energy expenditure is the same—FGF21. He also mentions that obesity is a state in which FGF21 resistance is likely. So, if you're obese and part of the 44% with a genetic variant, it’s very possible that neither of these diets will work as intended. Based on his interpretation of the study, the warning he gives about the sugar diet should absolutely apply to keto too.

13 hours ago, Nick Heaz said:

the warning he gives about the sugar diet should absolutely apply to keto too.

I disagree because a keto diet is proven to be a healthy way of eating that is sustainable for a lifetime. A sugar diet is not.

20 hours ago, Nick Heaz said:

This is a really great video and definitely something anyone should watch and understand if they’re considering trying keto or sugar fasting.

In the video, Nick Norwitz explains that both high-carb, low-protein (sugar fasting) and high-fat, low-protein (keto) diets elevate FGF21, which is the hormone responsible for increasing fat metabolism by raising energy expenditure. He also notes that genetic variants in FGF21 are extremely common—present in about 44% of people. If you have one of these variants, your FGF21 levels may not increase as expected on either diet, which means you might not experience the same rise in energy expenditure—and could even gain weight.

So why does he only offer caution about the sugar diet? That seems incredibly biased. I believe the same level of caution should be applied to keto as well, especially since, by his own explanation, the mechanism behind weight loss and increased energy expenditure is the same—FGF21. He also mentions that obesity is a state in which FGF21 resistance is likely. So, if you're obese and part of the 44% with a genetic variant, it’s very possible that neither of these diets will work as intended. Based on his interpretation of the study, the warning he gives about the sugar diet should absolutely apply to keto too.

Because the sugar diet will cost you your liver/pancreas. It comes with a cost more severe than just weight gain or loss. The risk of a sugar diet is thus, much higher. Other reasons could be severe glycation damage, dopamine/addictive response to sugar, constant elevated insulin levels, teeth decay (ask a vegan). None of these are an issue with high fat. That said, don't go low protein, ever.

Protein and fat are essential, carbs however, are not. Ever.

Losing weight means nothing, if it comes with a cost. Losing muscle will absolutely lead to problems.

7 hours ago, Geezy said:

I disagree because a keto diet is proven to be a healthy way of eating that is sustainable for a lifetime. A sugar diet is not.

The sugar diet is what we saw in the nineties, but it was called low fat. It's when fatty liver disease doubled in the population and no longer just happened to alcoholics.

8 hours ago, Geezy said:

I disagree because a keto diet is proven to be a healthy way of eating that is sustainable for a lifetime. A sugar diet is not.

Sugar diet is not designed to be sustained for a lifetime. Nobody is recommending anyone become vegan. The difference that I see is many people on carnivore and keto diets deal with extreme disordered eating in their past like sugar addiction or they suffer from abnormal food intolerances and cannot consume other foods. Most people on the sugar diet that I'm aware of are just wanting to be less fat.... and it's working 😎

Edited June 8Jun 8 by Nick Heaz

1 hour ago, Orweller said:

The sugar diet is what we saw in the nineties, but it was called low fat. It's when fatty liver disease doubled in the population and no longer just happened to alcoholics.

We all know this was due to the huge increase in ultra-processed and hyperpalatable foods that pair carbs with fat. No one wants to talk about the huge excess amounts of fats the SAD diet includes. Sugar is blamed 24/7 but the next time you're at the grocery store take a look at the ingredients on the processed food. I think you'll be surprised by the amount of fat in there. Sugar diet leans you out primarily because it doesn't drastically cuts that amount of fat intake.

Edited June 8Jun 8 by Nick Heaz

1 hour ago, Nick Heaz said:

We all know this was due to the huge increase in ultra-processed and hyperpalatable foods that pair carbs with fat. No one wants to talk about the huge excess amounts of fats the SAD diet includes. Sugar is blamed 24/7 but the next time you're at the grocery store take a look at the ingredients on the processed food. I think you'll be surprised by the amount of fat in there. Sugar diet leans you out primarily because it doesn't drastically cuts that amount of fat intake.

I think you should try the sugar diet for a year and report back. You have an interesting thesis here.

I dunno man, So is there a plan when your sugar fast is over?

17 minutes ago, Orweller said:

I think you should try the sugar diet for a year and report back. You have an interesting thesis here.

If things continue at the rate they're going now, I'll likely need another 3 -4 months to achieve my weight loss goal. I started at 226lbs 1 month ago. Current weight is 215lbs. Goal is 175-180. I'm eating meat 2-3x / week right now. Usually a hanger or skirt steak for dinner.

My assumption is that short bouts of high carb (2-3 days straight) offset by a meat day will reduce any negative effects from glycation or fructosylation.

For the amount of weight I need to lose an entire year on the diet seems excessive. I'm not trying to turn into a malnourished soy boy lol

The plan is to achieve my weight loss goal followed up by a diet that resembles Paul Saladino's, though I likely won't require that many carbs at that time.

To distinguish myself and my goals from many on carnivore, I do not suffer from any autoimmune conditions, sugar addiction, and I have no food intolerance issues. I'm not on the same health journey as many that may be in this forum.

Maybe the difference is a person's end goal, maybe make a mission statement to kick the diet off to which ever path the person chooses.

"I want to step on the scale and see a lesser number over the next 90-120 days". "My goal is to lose X amount of pounds"

With these two statements probably 99% of all diets are effective. These statements will lead to the 'calories and calories out' conversation and before the definition of calories pops up, we can change it to 'total mass in and total mass out'. This approach makes all diets really close to 100% effective.

Next mission statement would be, "I would like to lose X number of pounds and improve my metabolic health at the same time". This wipes out a really large chunk of most diets. They are effective but the metabolic health, which is probably not up to snuff in the first place, will take a further hit as the weight goal is approached or attained'.

I can see this approach for someone really big who needs to drop X number of pounds to be able to go under a knee or hip replacement, or similar surgeries. Getting the weight down can be by any means necessary. The plan would be weight comes down, surgery takes place, mobility is returned and then a better meal plan can be coupled with mobility for a healthier life. I can see this being an option for a lot of people.

Then maybe the last mission statement would be "I want to improve my metabolic health, and in time drop some weight, and at the same time develop a sustainable long-term way of eating". This narrows the field. And if I added "without the required need of daily supplementation" we get down to the animal-based versions of carnivore and a minimal number of the keto versions with a carb/sugar level fairly low.

Over the past three to four months, I have both gained and lost weight on a strict carnivore diet purely based on the mass I am eating, the timing in which I eat even coupled with several 96-hour water fasts. Last week I laid off the eating to hit the protein target, pretty much ate when I was hungry (which turned into OMD, if that) and dropped from 219 to 212 in 7 days. As always, there is some daily fluctuation and four pretty good days in the gym. I also walked a couple days 3.5 miles with at least 100 pushups along the walk. The weeks before that with the same out-put, I crammed 200 grams of protein per day in via the same strict carnivore diet, and I gained 8-9 pounds.

I am the only control subject in my study (LOL) but my approach 'will both lose and gain weight dependent on food intake', it has been proven to improve my metabolic health (numerous blood tests from BP, to glucose, to lipid panel, to kidney function, to immunoglobulin/autoimmune response) and I have shown it is completely sustainable for me over time.

100% of all diets will work and 100% of all diets will fail. Diet success is pounds in the short-term, but that success is all too often short-lived. Diets that evolve into sustainable lifestyles is where the true successes land.

And with that said, I can see the need and the point of 'losing weight' by any means necessary.

Scott

On 6/7/2025 at 9:01 AM, Nick Heaz said:

So why does he only offer caution about the sugar diet? That seems incredibly biased. I believe the same level of caution should be applied to keto as well, especially since, by his own explanation, the mechanism behind weight loss and increased energy expenditure is the same—FGF21.

That would assume that FGF21 is the sole mechanism behind weight loss. I don't think this is the case nor what Nick was implying. That said, yes, Nick is going to be biased because he is pro-Keto. But for good reasons. Protein and fats are essential for human health. Carbs and sugars aren't. Plus, the excess consumption of carbs and sugars can be detrimental. Eating Carnivore or Keto resembles a natural human diet. Gorging on candy does not. Even fruit was available only for a limited time and in limited quantities in ancient times.

But with that said...

11 hours ago, Nick Heaz said:

Sugar diet is not designed to be sustained for a lifetime... Most people on the sugar diet that I'm aware of are just wanting to be less fat.... and it's working 😎

Modern technology does allow us to manipulate things. Without it you couldn't eat all this fruit or candy. Thanks to science and technology, people can actually be vegan and survive - with supplementation. None of this could have been done a short while ago. But this is why I say in my video that I would hope one returns to a normal, natural, sensible pattern of eating even if they decide to do the sugar diet.

9 hours ago, Nick Heaz said:

My assumption is that short bouts of high carb (2-3 days straight) offset by a meat day will reduce any negative effects from glycation or fructosylation.

Or not. However, the human body can probably tolerate and repair itself from the abuse if it goes on for a little while. But if sugar fasting or sugar dieting were practiced long term, the consequences could be real. But what "long term" means for one person will be different from another.

If your younger or healthier, you can probably pull this off.

I mean, I was 47 when I finally adopted a proper human diet. For those first 47 years, I damaged myself pretty hard. I've healed tremendously but still have some healing to go. And it may be that some of that damage from my previous [sugar-laden] diet might never fully heal.

But I understand the principle that sugar fasting could be a "tool" in one's toolbox.

9 hours ago, Nick Heaz said:

The plan is to achieve my weight loss goal followed up by a diet that resembles Paul Saladino's

That would be a good goal. I have a lot of respect for Paul, although his version of an "animal-based" diet might just be a sugar diet with all of the fruity carbs he recommends on the daily. I am not anti-fruit, but I think it should be enjoyed in much lesser quantities than he advises.

16 hours ago, Nick Heaz said:

No one wants to talk about the huge excess amounts of fats the SAD diet includes

Yes but that was all seed oils not animal fats.

16 hours ago, Nick Heaz said:

Sugar diet is not designed to be sustained for a lifetime. Nobody is recommending anyone become vegan. The difference that I see is many people on carnivore and keto diets deal with extreme disordered eating in their past like sugar addiction or they suffer from abnormal food intolerances and cannot consume other foods. Most people on the sugar diet that I'm aware of are just wanting to be less fat.... and it's working 😎

Oh I’m fully aware of that but there are going to be a lot of people out there that think this is going to give them cart-blanch to just eat all the sugar they want. In fact one of the influencers was pretty much just saying that today. I’m already staring to see fat people reporting in that they’ve been doing this and not achieving any weight loss. The only ones I’m seeing having any results are the skinny people who have high metabolisms.

It’s already been proven that I can lower my cholesterol (not that I’d want too) by just eating Oreos but that don’t make it healthy.

Edited Monday at 03:20 AM5 days by Geezy

On 6/8/2025 at 8:50 AM, Nick Heaz said:

My assumption is that short bouts of high carb (2-3 days straight) offset by a meat day will reduce any negative effects from glycation or fructosylation.

Glycation damage is permanent, remember this. Every time your blood sugar hits over a 100, you're redlining. That is my concern.

On 6/8/2025 at 8:50 AM, Nick Heaz said:

I'm not trying to turn into a malnourished soy boy lol

At least you're aware of the hormonal reaction of sugar, and the loss of muscle when on low protein. Yet another concern for me.

On 6/8/2025 at 8:50 AM, Nick Heaz said:

I'm not on the same health journey as many that may be in this forum.

Yup, at the end of the day we each have our own journey.

On 6/8/2025 at 8:32 AM, ketomonster said:

I dunno man, So is there a plan when your sugar fast is over?

The plan will be healing, is my guess. Organs WILL take a hit due to glycation, aging will occur as well during such a diet. We ALL agree it's a non sustainable diet for these reasons. And that is where carnivore and sugar diet are vastly different. Myself, I choose for a sustainable diet, but to each their own.

If someone tells me, hey you can do this, it's fine, but only for so and so time span.... then I am out. The poison is always in the dose, yes, but if you can avoid it, then why not? Both diets may lead to weight loss, but one will come with potential risks and a possible recovery from the damage done.

10 hours ago, Geezy said:

Yes but that was all seed oils not animal fats.

Not only that, it is also the amounts of fat COMBINED with even more sugar. The fat of course gets the blame for the crime of sugar. The mechanisms behind sugar intake are universally acknowledged, Randall cycle, glycation, etc.

You can't put diesel and regular gas in a car. That's the simple way to put it, as flawed as this analogy may seem.

In order for this sugar diet to work, you have to eliminate fat and protein, two essential components, and these components are replaced by a non essential component, void of nutrients that are found in the aforementioned macro nutrients. No wonder people lose weight, it's called wasting away.

It is not as such that we can't lose weight on carnivore, it just takes longer, and is more challenging.

On 6/8/2025 at 8:57 AM, Scott F. said:

Maybe the difference is a person's end goal, maybe make a mission statement to kick the diet off to which ever path the person chooses.

"I want to step on the scale and see a lesser number over the next 90-120 days". "My goal is to lose X amount of pounds"

With these two statements probably 99% of all diets are effective. These statements will lead to the 'calories and calories out' conversation and before the definition of calories pops up, we can change it to 'total mass in and total mass out'. This approach makes all diets really close to 100% effective.

Next mission statement would be, "I would like to lose X number of pounds and improve my metabolic health at the same time". This wipes out a really large chunk of most diets. They are effective but the metabolic health, which is probably not up to snuff in the first place, will take a further hit as the weight goal is approached or attained'.

I can see this approach for someone really big who needs to drop X number of pounds to be able to go under a knee or hip replacement, or similar surgeries. Getting the weight down can be by any means necessary. The plan would be weight comes down, surgery takes place, mobility is returned and then a better meal plan can be coupled with mobility for a healthier life. I can see this being an option for a lot of people.

Then maybe the last mission statement would be "I want to improve my metabolic health, and in time drop some weight, and at the same time develop a sustainable long-term way of eating". This narrows the field. And if I added "without the required need of daily supplementation" we get down to the animal-based versions of carnivore and a minimal number of the keto versions with a carb/sugar level fairly low.

Over the past three to four months, I have both gained and lost weight on a strict carnivore diet purely based on the mass I am eating, the timing in which I eat even coupled with several 96-hour water fasts. Last week I laid off the eating to hit the protein target, pretty much ate when I was hungry (which turned into OMD, if that) and dropped from 219 to 212 in 7 days. As always, there is some daily fluctuation and four pretty good days in the gym. I also walked a couple days 3.5 miles with at least 100 pushups along the walk. The weeks before that with the same out-put, I crammed 200 grams of protein per day in via the same strict carnivore diet, and I gained 8-9 pounds.

I am the only control subject in my study (LOL) but my approach 'will both lose and gain weight dependent on food intake', it has been proven to improve my metabolic health (numerous blood tests from BP, to glucose, to lipid panel, to kidney function, to immunoglobulin/autoimmune response) and I have shown it is completely sustainable for me over time.

100% of all diets will work and 100% of all diets will fail. Diet success is pounds in the short-term, but that success is all too often short-lived. Diets that evolve into sustainable lifestyles is where the true successes land.

And with that said, I can see the need and the point of 'losing weight' by any means necessary.

Scott

Really appreciate your responses.

1 hour ago, Orweller said:

Not only that, it is also the amounts of fat COMBINED with even more sugar. The fat of course gets the blame for the crime of sugar. The mechanisms behind sugar intake are universally acknowledged, Randall cycle, glycation, etc.

You can't put diesel and regular gas in a car. That's the simple way to put it, as flawed as this analogy may

11 hours ago, Geezy said:

Oh I’m fully aware of that but there are going to be a lot of people out there that think this is going to give them cart-blanch to just eat all the sugar they want. In fact one of the influencers was pretty much just saying that today. I’m already staring to see fat people reporting in that they’ve been doing this and not achieving any weight loss. The only ones I’m seeing having any results are the skinny people who have high metabolisms.

It’s already been proven that I can lower my cholesterol (not that I’d want too) by just eating Oreos but that don’t make it healthy.

seem.

In order for this sugar diet to work, you have to eliminate fat and protein, two essential components, and these components are replaced by a non essential component, void of nutrients that are found in the aforementioned macro nutrients. No wonder people lose weight, it's called wasting away.

It is not as such that we can't lose weight on carnivore, it just takes longer, and is more challenging.

1 hour ago, Orweller said:

Not only that, it is also the amounts of fat COMBINED with even more sugar. The fat of course gets the blame for the crime of sugar. The mechanisms behind sugar intake are universally acknowledged, Randall cycle, glycation, etc.

You can't put diesel and regular gas in a car. That's the simple way to put it, as flawed as this analogy may seem.

In order for this sugar diet to work, you have to eliminate fat and protein, two essential components, and these components are replaced by a non essential component, void of nutrients that are found in the aforementioned macro nutrients. No wonder people lose weight, it's called wasting away.

It is not as such that we can't lose weight on carnivore, it just takes longer, and is more challenging.

I also hold the opinion that it’s not a strategy that should be utilized long-term. As you mentioned, glycation is something to be factored in. I still hold the opinion that short bouts of the sugar diet does not lead to irreversible effects caused by glycation and this can easily be monitored by taking a look at HbA1c every 3 months. I surely don’t believe 2-3 days of sugar fasting followed by meat consumption is causing AGE accumulation.

12 hours ago, Geezy said:

Oh I’m fully aware of that but there are going to be a lot of people out there that think this is going to give them cart-blanch to just eat all the sugar they want. In fact one of the influencers was pretty much just saying that today. I’m already staring to see fat people reporting in that they’ve been doing this and not achieving any weight loss. The only ones I’m seeing having any results are the skinny people who have high metabolisms.

It’s already been proven that I can lower my cholesterol (not that I’d want too) by just eating Oreos but that don’t make it healthy.

12 hours ago, Geezy said:

Oh I’m fully aware of that but there are going to be a lot of people out there that think this is going to give them cart-blanch to just eat all the sugar they want. In fact one of the influencers was pretty much just saying that today. I’m already staring to see fat people reporting in that they’ve been doing this and not achieving any weight loss. The only ones I’m seeing having any results are the skinny people who have high metabolisms.

It’s already been proven that I can lower my cholesterol (not that I’d want too) by just eating Oreos but that don’t make it healthy.

Your mention of fat people failing the sugar diet is spoken about directly by Nick Norwitz in the video and he offers a potential reason why. I’m posing the question of why he didn’t offer the same caution to obese people trying keto considering he provides the same mechanism for fat loss while in ketosis, elevation of FGF21. Perhaps this is the same mechanism for people not having success in ketosis.

On 6/8/2025 at 6:04 AM, Nick Heaz said:

We all know this was due to the huge increase in ultra-processed and hyperpalatable foods that pair carbs with fat. No one wants to talk about the huge excess amounts of fats the SAD diet includes. Sugar is blamed 24/7 but the next time you're at the grocery store take a look at the ingredients on the processed food. I think you'll be surprised by the amount of fat in there. Sugar diet leans you out primarily because it doesn't drastically cuts that amount of fat intake.

Regardless of which regimen you decide on the lifestyle you mention above has been proven to make humans ill because we're not

adapted to consuming seed oils for long time.

UPF are made up of those said seed oils, but there are some that are made with ANIMAL fats then you have that fake color, flavor and sugar

added which defeats the "it's using HEALTHY fats" argument (moot point)

I'm smoking nicotine free cigs SMH <<< see how dumb that sounds?

We're open to fresh ideas, possiblilities of different foods helping our health but WHOLE FOODS

are the ONLY proven sustainable regimen humans can use for a healthy lifestyle.

Jack LaLanne was before his time. He went down a different path....

He ate vegetables, juiced (fruits/veg), and even ate fish but didnt eat other meats.

What works for him may or may not work for alot of people.

6 hours ago, Nick Heaz said:

I also hold the opinion that it’s not a strategy that should be utilized long-term. As you mentioned, glycation is something to be factored in. I still hold the opinion that short bouts of the sugar diet does not lead to irreversible effects caused by glycation and this can easily be monitored by taking a look at HbA1c every 3 months. I surely don’t believe 2-3 days of sugar fasting followed by meat consumption is causing AGE accumulation.

I think when you talking about mere days, now that is an entire different discussion. Eating different for a few days is not really a diet, nor it is fasting -because we eat. It's going off the rails but WITHOUT the fat and protein. And that may make that binge a lot safer. I can definitely see that.

The only thing that puzzles me, is the wording. Diet, and fasting is used, but neither is the case, which makes me consider it rhetoric, euphamisms, if you will. The best thing is to be honest and say -I am going to eat shit loads of sugar as safe as possible for a few days to perhaps, lose weight, or seek an insuline response. If someone would use those words, it'd be easier to understand. But the whole thing is veiled under words that "sound" healthy. While in fact it's a somewhat risky venture in order to lose weight real fast.

And if people want to try it out, I am okay with it. I keep an open mind. If sugar diet works, I'd be delighted! I'd make Little Debbie's rich!

But having seen a similar movement in the nineties, I see it's but a cotton candy colored dream.

So you'd agree that it's a really short term strategy, rather than a diet?