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Sustainability of Low Carb Nutrition

"What about the sustainability of low carb nutrition?" It’s the response from almost any registered dietician and many lay people when low carb comes up.


Among the most common objections that nutrition professionals raise about low carb nutrition is that it’s not sustainable.

“How can it be?” they cry, “You’re eliminating an entire macronutrient from your diet.”

In this article, I want to examine the “sustainability of low carb nutrition” by addressing some simple questions. As much as one can do studies to prove something works or doesn’t work, depending on your bias, there is plenty of evidence that low carb nutrition does, indeed, work and is sustainable for a significant number of people.

For many readers, this is your lived experience and very little that I write is new to you. Hopefully, this article will prove useful as a resource you can point people to when they challenge you about the sustainability of low carb nutrition.

1000’s of Anecdotes

Contrary to the popular misquote, the plural of anecdote IS data.

If 1000’s of people have a similar experience, then there has to be some real world validity to the claim that what they are doing works.

What’s more, why would these people lie? Unlike many of the researchers who vehemently deny the efficacy and sustainability of low carb nutrition, most have nothing to gain.

They’re not trying to sell a product or service.

They’re not trying to publicise the results of an academic study they conducted.

They have no sponsors to keep happy, no free product or endorsement cheques to lose.

Instead, they’ve had an experience. What they did worked for them, often after years of trying all the mainstream approaches and failing, predictably, every time.

Why would they not want to share something that worked for them with everybody they meet who is in a similar position to where they started?

Sometimes, the mechanism they explain might be wrong. But the mechanism doesn’t really matter, the results do.

If the researchers who complain about and vilify “low carb zealots” were anything other than disingenuous, they would recognise that something is happening that contradicts their view of the science, put their bias to one side and investigate the mechanism that underpins the results being achieved.

Sadly, they don’t do this. Instead, they pick apart people’s explanations of how they think this thing that has worked so well for them works. They insist that it’s no better than any other approach. Or they simply accuse people of lying.

They do this under the guise of wanting to protect the public, but all they really wish to protect is their egos.

For many, if not most, people who have found success with low carb nutrition this is not their first rodeo.

Anyone who has a significant long-term weight problem will have tried a multitude of approaches; counting calories, calculating macros, points, juicing, plant-based, meal replacements, low fat and the list goes on. Like 97% of people on any diet, they failed.

Low carb nutrition works for them because…

It’s not a diet, it’s a lifestyle in which they do not have to be hungry all the time in order to improve their body composition.

For those with type 2 diabetes (T2DM) and pre-diabetes, they’ve almost certainly followed the standard of care, with its advice to get the bulk of calories from carbohydrate-containing foods and to limit dietary saturated fat. They’ve accepted that T2DM is a progressive, incurable disease and have submitted to ever increasing doses of insulin to control their blood sugars. And they’ve suffered the consequence in their declining health.

Low carb nutrition works for them because…

It’s not a diet, it’s a lifestyle in which they can control their blood sugar and insulin without resorting to long-term, health-destroying medication.

Why would anyone believe that these folks are not the experts on the sustainability of low carb nutrition?

Common Objections

Here is a selection of common objections to the sustainability of low carb nutrition, that simply need to be squashed.

You’re Excluding a Whole Food Group/Macronutrient

Firstly, you’re not excluding carbohydrates, you’re minimising them.

In fact, a diet containing 15% of calories from carbs is considered by many low carb folks to be a low carb diet (in a 2000kcal diet, that’s 75g or less of carbs per day. A lot of people do well at this level.

A classic low carb diet calls for less than 50g of carbs per day.

Even a ketogenic diet is not a “no carb” diet. It’s just a very low carb diet at less than 20g of carbs per day.

So, you’re not excluding a whole macronutrient.

Of course, even if you were to miraculously get absolutely zero carbohydrates from your diet - the carnivores get closest but even muscle meat contains glycogen - you’d still be fine because there is no such thing as an essential carbohydrate. In other word, you don’t need to get it from your diet, your body can make what it needs.

As to excluding food groups, I’d say that it’s bit rich for a dietetics profession (and they’re the first to jump on the anti-low carb bandwagon) that touts vegan and vegetarian diets which absolutely BAN whole food groups to rabbit on about removing food groups.

As for a public that are being hoodwinked into believing that less meat is better for human health and the planet, they’re little better on the “removing a food group” front.

Yes, for the most part, you’re going to remove sugar, grains legumes, pulses and starchy vegetables from your diet, or at least reduce them a lot. But these are foods that contain poor levels of essential nutrients and high levels of plant chemicals that inhibit the absorption of any nutrients they do contain. What exactly are you missing out on when you don’t eat them?

As a low carber, once you're fat-adapted, you’re always free to have some higher carb days if those work for you. There’s no judgement here. In fact, this is exactly what people on a cyclical ketogenic diet (CKD) do every week. Some people find a CKD really effective, others don’t. Both are OK.

This flexibility is part of the sustainability of low carb nutrition.

The Weight Just Goes Back On When You Stop

All diets fail.

The statistic is that 97% of people who follow a diet fail and regain all the weight lost within 3 years. In fact, it’s usually within months, not years.

If you treat low carb nutrition as a diet, the failure rate isn’t likely to be much different. Once you stop eating a low carb diet and go back to the Standard American (Western) Diet, the weight is probably going to return.

I’m confident that if you lose weight using a calorie controlled diet, where you weigh and measure everything you eat, it would be possible to lose weight and keep it off forever, as long as you keep weighing and measuring everything forever.

It would be difficult to do and few if any succeed because you’d have to accept that you’d always be hungry. But that’s not the point. The point is that that you COULD do it IF you stayed on the diet indefinitely.

The best test of how sustainable this approach is, is bodybuilders working towards a competition. They do exactly this, they weigh and measure everything they eat. In fact, this is where the whole CICO thing really began as a mainstream approach. In the very early 2000’s, I bought a very thick ebook, written by a bodybuilder, that detailed exactly how the average person could do CICO well.

How many bodybuilders are contest lean all year round? None.

Not to mention that most bodybuilders and physique competitors in a cutting phase are hungry and miserable almost all the time. Afterwards, most of them simply get fat again.

The reasons why any diet will fail unless you stay on it indefinitely may be a little different, depending on the diet, or they may not. It doesn’t really matter. The result is what’s important.

It’s Just Water Weight

It’s true that when you initially start a low carb diet, you lose a lot of water.

That’s because in the early days, your body isn’t great at burning fat and so it uses your muscle glycogen to provide the glucose it’s looking for, before that also runs low. For every gram of glycogen you store, you also store 3-4g of water. Use the glycogen and the body sheds the water.

Once the glycogen runs low, many people suffer the “low carb flu” or “keto flu” before their bodies make the switch to using a majority of fat for fuel. This usually takes about 3 weeks to achieve for basic fat adaptation and quite a bit longer to gain more advanced athletic benefits, if that’s what you’re after.

Once you’re basically fat-adapted, your body restores those glycogen stores. It has to do this, because glycogen stores are a survival mechanism for use when fast energy is required. So, when you refill those glycogen stores, you also replace the water that was lost when they were depleted.

The result is simple. Within a few weeks of starting your low carb diet, your glycogen-associated water stores are close to or the same as they were before you began. Yet, most people will not see an increase in body mass as a result. Why? Probably because they are now using stored body fat for fuel and losing weight that way instead.

Just so that you know how much this initial weight loss could be, here are a few numbers…

The average person stores about 500g of glycogen in the liver and muscles (this varies by body mass, training status etc.). Complete depletion will never happen, but let’s just assume it does. If the person has 4g of water stored per gram of glycogen, depletion would cause them to lose 2.5kg (5.5lbs), of which 2kg (4.4lbs) is water.

There are probably other tissues that lose water in the early days of a low carb diet but, once again, if this is essential water, the body will restore it fairly quickly in order to regain homeostasis.

Even where this water loss is permanent and thus isn’t replaced, that means it's not essential water. Why would you want to be carrying around excess water any more than you want to be carrying excess fat?

It’s Expensive

How expensive your food ends up being depends almost entirely on how complicated you want to make the food that you cook. My usual main meal of the day is lunch (it’s also breakfast because it’s the first time I eat) which would cost less than £2.50 (just over $3) if I used the cheapest ingredients possible.

Of course, if you go from eating cheap ready meals to trying to cook gourmet low carb food with lots of ingredients, it will cost significantly more. My point is that it doesn’t have to.

Then, there’s the nutrition argument, which is covered more below, but it’s relevant here and I love this tweet from Bob...

Follow Bob on Twitter

This sums up the cost angle quite nicely. I’d then extrapolate it further and look at the bioavailable nutrients per £/$. If your health matters to you, there really is no contest.

Add in the fact that you won’t need to eat snacks every few hours and the grocery bill quickly becomes equivalent to what you probably spend now.

Many folks on a low carb diet only eat once or twice a day; that’s the cost of a whole meal saved every day.

Eating an animal-based low carb diet also means that you can do away with most, if not all, regular food supplements. It’s not a lot, but it’s another saving.

Finally, you have to ask yourself whether a small saving on the food budget today is worth the issues that might well arise down the line from metabolic disease like T2DM, which is strongly associated with the high carb Standard American Diet.

I Can’t Live Without Cake

This is where my sympathetic side vanishes.

Absolutely nobody NEEDS cake (or other confectionery). If the choice is health or something filled with sugar, the choice is very clear to me.

I would understand if there was something in cake that we needed to survive and thrive. There isn’t, so I have no sympathy for this argument.

But we’re all individuals and we all have the right to choose how we live. It’s just that choosing sugar over your health makes no sense to me.

We Need Fibre for Health

This is a huge subject and I can’t do it justice here. It’s also a very science-heavy one and I prefer to leave the explanations of research and biochemistry to people who are skilled in those fields.

I don’t believe fibre is necessary for human health. I manage perfectly fine without significant amounts of fibre in my diet and I know a lot of others who claim the same. If anything, I find my digestion is better without it.

Nobody is the “last word” on anything, but Dr Paul Mason is someone whose opinion I trust. Have a look at what he has to say, perhaps have a look at others and then make an informed decision.

That said, it’s perfectly possible to eat more fibre on a low carb nutrition plan if you include plenty of leafy and above-ground vegetables. Be aware that some people are more sensitive to plant phytochemicals than others and, if you find you’re not getting the results you hoped for, try removing the plants, starting with the leafy green ones.

Athletes and Lifters Can’t Perform on Low Carb

This one is just bro-science nonsense.

The belief that you need carbs to train or perform at anything other than the absolute highest levels of performance is perpetuated by sports nutrition companies and their tame sports scientists. Remember, these people all have something to sell you.

I wrote about the low carb athlete in a separate article.

In simple terms, your body makes and stores glucose as glycogen in your liver and muscles for later use. Above certain levels of exercise output, you begin to use your stored glycogen, but the required intensity levels are significantly increased for athletes on a habitual low carb diet.

The average person has enough stored glycogen to fuel ±90 minutes of exercise at an intensity many refer to as Functional Threshold. This is pretty hard, about the intensity you would expect to be able to sustain for an hour or so.

It’s easily possible for a low carb athlete to provide 10kcal per minute from fat stores. That’s theoretically enough fuel delivery to run a 4-hour 20 minute marathon on fat alone. Keep your pace under control and you’d be able to run faster by using some of that stored glycogen.

Some of the world’s best at using fat for fuel can get as much as 14kcal per minute from fat.

These guys ran 100 miles in 5 days on just water. How was their effort fuelled? Fat.

 The last thing to say on this is that you don’t have to use no carbs during high intensity exercise, you just won’t need as many if you’re properly fat-adapted.

Why is Low Carb Nutrition Sustainable?

Experts love to argue mechanisms. I’ve decided that on that basis, I don’t wish to be “an expert”.

I’m a coach, I’ve been a coach for a long time. In that time, I’ve often found “evidence-based practice”, by which I mean “arguing about mechanisms” to be an exercise in theoretical time-wasting.

I’m a practical guy. I find what works and apply it. I don’t much care why it works, I leave that to people who like to look down microscopes. I want the intervention that creates the real-world result.

That said, other than the answers to the objections above, here is how I answer when I’m asked about the sustainability of low carb nutrition.

Low Carb Foods Provide Satiation and Satiety

I always start here.

When it comes to having the body composition that a human being is meant to have, satiation and satiety are the key factors.

This is probably the main reason low carb nutrition works so well. It addresses both of these factors.

If you are hungry, you are going to want to eat and over time, that desire is going to become so strong that you’re going to give in. It’s a biological survival drive, unless you’re extraordinarily motivated, it will beat you.

It’s probably worth defining what I mean when I use these terms.

Satiation is the sensation, while you’re eating that you’re full. You’ve eaten enough at this meal, it’s time to stop.

Satiety is a more long-term effect. It’s the ability of the foods you’ve eaten to keep hunger at bay for extended periods.

Satiation is achieved partly through food volume, but also through the protein content of your meal. You can only eat so much protein before you can’t eat any more. It’s probably worth noting here that variety of foods is the enemy of satiation.

Satiety is the result of eating enough micronutrients and enough fat. This means your body has what it needs to thrive and doesn’t send you off on a food hunt half an hour after your meal.

Low carb nutrition achieves both and most people find that snacking becomes unnecessary. Many also find that they only need to eat once or twice a day.

The sustainability of low carb nutrition is, in no small part, due to these high levels of satiation and satiety.

Low Carb Foods Are Nutrient-Rich

As mentioned above, satiety relies on getting enough bioavailable nutrients in the food you eat.

Animal foods, which usually make up most of a well-formulated low carb nutrition plan are packed with the micronutrients required for optimal human function in a highly bioavailable (easily absorbable) form and without most of the anti-nutrients found in plants that hinder absorption of these nutrients.

This means that you do not have to eat enormous quantities of food in order to get what your body needs to thrive.

Without subscribing to the simple idea of “calories in, calories out”, one could still think of this as more nutrients per calorie, with the result that you don’t need to eat as many calories to get the nutrients you need.

Most people on plant-based diets or the Standard American Diet are always hungry. One reason is simply because their bodies are desperate for micronutrients and they’ll stay that way until they meet this need.

Much of the world is no longer calorie-deficient, they’re nutrient-deficient. Obesity is a symptom of malnutrition much the same way as starvation; people’s bodies are starving for nutrients. It’s just that the overfed are storing away the calories as fat and setting themselves up with metabolic disease in the process.

Low Carb Nutrition Helps to Control Insulin

This is the big one for diabetics and people with other metabolic disorders.

Low carb diets have been shown to put T2DM in remission.

Chronically elevated insulin is simply not good for your body and eventually, you become so resistant to it that your pancreas can no longer produce enough to keep your blood glucose in the correct range.

It’s not unreasonable to blame elevated insulin for many of the chronic diseases of modern life; Type 2 Diabetes, heart disease, high blood pressure, obesity, kidney disease and many others have been shown to have links to chronically high insulin levels.

Once you control insulin by removing the majority of carbs from your diet, many of the disease symptoms subside. In comparison with the downhill slide or what seems like a long, slow death, the energy and health that most people start to experience makes this a way of eating that just makes sense. Why would you go back to eating food that so obviously makes you sick?

Once again, it’s possible to put T2DM in remission by losing weight on a very low-calorie diet (around 850kcal versus the 2-2500kcal considered right for the average person. How on earth will anybody sustain weight loss or even live a halfway good quality life on that level of food intake. The answer is they won’t; they’ll be hungry, they’ll be miserable, and they’ll relapse. What type of life is that?

Beyond metabolic disease, better insulin control also adds a satiety benefit. When you’re not on the blood sugar rollercoaster, you have no need to snack constantly.

Just in case someone isn’t aware, here’s a super simplified version of the blood sugar rollercoaster.

When we eat carbs (and protein to a small degree), our blood sugar becomes elevated. Because the body needs to keep glucose in a tight range around 4g, the pancreas secretes insulin to tell the cells to remove glucose from the bloodstream.

Blood glucose then drops below the ±4g level, the body recognises the need to raise it and you get hungry again. You eat, and the whole cycle repeats.

In contrast, in someone who eats a low carb diet, the insulin response is smaller because blood glucose doesn’t rise nearly as much. It then doesn’t fall as precipitately, and you don’t suddenly find yourself ravenously hungry an hour or two after your last meal.


The sustainability of low carb nutrition might well be described as “in the eye of the beholder”.

More accurately, the only person who can assess the sustainability of low carb nutrition is someone who has given it a fair trial in their own life.

There are a lot of such people and they’re thriving on a diet of meat, eggs, dairy and seafood.

They show no signs of nutritional deficiency.

They’ve lost and kept off amounts of weight that make people question whether their claims can be true (until you see the photos).

They’ve come off medications that they expected to be on for life.

And they’ve done all this without being hungry and whilst eating all the foods that your doctor has told you, for years, will give you heart disease.

In the end, you have to do you.

The choices you make affect your health, not that of your doctor or dietician. And whatever advice they give you, they get paid whether you thrive or whether you get sick.

This is ultimately the answer to the sustainability of low carb nutrition: Does it work for you? Is it something you can sustain?

After over 6 years, I know that answer for me. What’s yours?

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Will Newton

In over twenty years of coaching, I have coached everyone from absolute beginners to world champions. My interest in getting the best results for people who train for health and fitness or the love of sport, rather than as professionals, drives me to find the most effective ways to get results. My mission is simple: Be in better shape at 70 than most people are at 20, and to help you do the same.

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