Last time, we looked at the foundations of our fat-loss journey – getting a handle on calorie intake, removing processed food, and prioritising nutrients over energy. That discussion, along with the one surrounding hormones back in Part 3, led to a lot of talk about carbohydrates. Today, let’s start by taking a bit of a closer look at the very low-carb ketogenic and carnivore ways of eating. Let’s ask ourselves if those approaches might support our fat loss. 


A ketogenic diet is one where our intake of carbohydrate is so low – less than about 30g per day – that our liver begins to produce ketone bodies from fat, which our cells can use as an alternative to glucose. A state of deep ketosis requires that our intake of protein is also moderated, because if we have high dietary protein, we can drive the creation of glucose via gluconeogenesis. In effect, ketosis is the body’s answer to the question ‘What will I do for energy, when there isn’t much to eat?’ Indeed, the most effective way to trigger deep ketosis is to fast for a couple of days. Most people are surprised at how unexpectedly good they feel – how alert and full of energy, and that’s down to ketones.


And of course it makes sense that we’ve adapted this way – if our survival depends on finding more food, we’re not going to last long if we crumble at the first sign of scarcity, incapacitated by fatigue and hunger. Alongside a number of wider, physiological benefits, ketosis suppresses that distracting hunger, and provides us with an acute state of alertness, focus and vigilance that allows us to address the problem at hand. Today, many ketogenic dieters enjoy that heightened focus, a suppressed appetite, and what appears to be a metabolic advantage of some 2-300 calories per day in increased energy expenditure. Ketosis can make for an extremely effective weight-loss tool, which makes total sense: In order to be in deep ketosis, we’re going to be burning our body fat to create those ketones. Or are we?


The level of the ketone body beta-hydroxybutyrate in our blood has become a popular metric for the depth of ketosis. If we are seeing high levels of serum ketones while in a calorie deficit, we can be sure that we are burning a lot of body fat, and because insulin will be low, that we’ll be burning it all the time. People therefore use their BHB measurements as a proxy for fat loss, and will go to great lengths to increase those numbers. One way in which we can do this is to eat more fat, driving the creation of ketones. We hear phrases like ‘eat fat to burn fat’ but the more energy we eat, the more we will replenish our fat stores, and the less body fat we will lose overall. By chasing higher ketone readings in this way, we can wind up stalling our fat loss, or even gaining fat. Equally we do ourselves no favours by starving to very deep levels of ketosis. We need to be wary of what that scarcity signal might do to our metabolic rate. While many of us in the developed world badly need a little more scarcity in our lives, we need to tread carefully.  


Today, there’s a rather misguided dogmatism in the keto world, with some advocates insisting that all human beings should be in deep ketosis all the time – that eating a quantity of carbohydrate or protein that takes us out of ketosis is a failure bound to result in ill-health. This notion is based on the assumptions that ancestrally we existed almost entirely on fatty meat, and that our default metabolic state was one of ketosis. 


These assumptions are shaky. While there is considerable evidence for the prioritisation of meat in the ancestral diet, it’s undeniable that we also included carbohydrates. Surviving hunter gatherer tribes offer us a limited window to the past, and their passion for honey, the risks they take to obtain it are both telling, and unsurprising: Why wouldn’t we eat it if we could? Why wouldn’t we eat fruit? And of course our biology, our ability to deal with sugars confirms that these are foods we have evolved to eat.


But we should note that evolutionarily consistent quantities would likely have been, well, inconsistent. Our ancestors would not have had uninterrupted access to their various sources of food. They might have gorged themselves on honey one day, and then gone several days without. After a big kill, their supply of meat would have displaced the need to gather fruits or roots for several days. Their carbohydrate intake might have been limited to certain months of the year. The point is that they were flexible. They could tolerate large boluses of carbohydrates, or be happy with none at all, in sharp contrast to the developed world, where we drip-feed sugar in at two-hourly intervals, day-in, day-out from the cradle, to the…well, to the grave. 


In the same way, the fact that we have the ability to enter deep ketosis at all, suggests that we occasionally needed to do so, but it was more likely to be during times of scarcity – starvation – rather than a default to ketogenic macros. After all, when meat was plentiful we’d have likely eaten ourselves out of ketosis even without extra carbohydrates. I’d argue that for most part, our ancestors were only occasionally deeply ketotic, and that their default state was more likely hovering around the fringes of mild ketosis – not necessarily above the 0.5 mmol that now qualifies as ‘nutritional ketosis’.  


Arctic populations, like the Inuit, are held up as being the definitive ‘ketogenic society’, on the basis that they wouldn’t have had any access to plant-based foods. However, studies of that population revealed that they were not in ketosis on their normal diet: Not only would their high protein intake have suppressed ketone production, but analysis of the marine animals that comprised their diet, showed them to be unexpectedly high in stored glycogen. But what’s really more interesting from our point of view is that they appear to have an adaptation that prevents them from easily producing ketones in any case. This begs the question ‘Why was that an advantage? Was it because there was some issue with long-term ketosis?’  


The answer is that we don’t really know. I’d offer the caution that if we’re going to judge chronically high carbohydrate intake to be at odds with our biology – a contributor to ill-health over a long period of time, in the interest of even-handedness we might grant that chronic ketosis could also negatively affect us over decades. With no historic populations that we can point to as evidence of the safety of this approach, we might hedge our bets and use ketogenic diets periodically, rather than on a permanent basis. This, we know, is firmly part of our design. 


That said, there are many individuals who maintain deep ketosis on a permanent basis, and seem to be doing very well – it’s almost certainly safe for a significant period of time, and has been shown to be of great benefit to those who have begun to struggle with blood glucose regulation. Some people use strict ketosis to keep certain types of cancer, types that are fuelled by glucose, in remission. If someone does better on a ketogenic diet, it would seem that for them, at that point in time, that’s the right approach. We always have to distinguish between what’s optimal for a sick person, and what might work well for the healthy. 


So what about all this carnivore nonsense? 


The carnivore diet, which excludes all plant foods, appears to be transformative in the same ways as the ketogenic diet – regulating blood sugar, controlling appetite and insulin. But it also seems, anecdotally at least, to alleviate the symptoms of various auto-immune diseases. While diabetes or prediabetes affect a shocking 60% of American adults, auto-immune issues have also skyrocketed. People report that by removing plant foods, all manner of symptoms seem to disappear overnight, and there are a growing number of clinicians who’ve adopted the approach. Maybe processed food, pollutants, stress or pathogens unknown cause our gut to become so dysbiotic, that we lose the ability to tolerate plants. Intestinal permeability gets out of control, and our immune system begins to react to the compounds which are passing through our intestine into our bloodstream?


The carnivore diet is seen almost as an extension of the ketogenic diet – keto on steroids – but it isn’t necessarily ketogenic at all. Many people on carnivore diets are eating more than enough protein to sidestep nutritional ketosis, yet they don’t seem to lose out when it comes to fat loss. If anything, people seem to report that carnivore was what allowed them to push past a weight-loss stall that they had encountered on keto. It’s hard to say for sure why this is, but it’s worth noting that the keto world can often be awash with processed food of its own – keto treats, bars and fat bombs. They might have no carbs, but they contain a lot of energy, and they can surely be hyperpalatable. Carnivore dodges these foods, and many proponents also avoid dairy, which is another common cause of weight-loss stalls. 


So, what does that tell us? It tells us that while periods of ketosis might well be part and parcel of a better approach to food, it’s not the ketosis itself that governs our success as we try to lose fat. Ultimately, it boils down to the core tenets that we’ve already covered in this series – the ability to maintain a calorie deficit by regulating appetite, hormones, metabolic rate and lean mass. What both ketogenic and carnivore diets seem to do for people, is to make it easier for them to build those pillars that ultimately support their fat loss. 


So what’s my experience of these diets? 


In my late thirties, what had previously been some mild intolerance to wheat and dairy developed into significant gut issues, chronic IBS-C and mixed IBS. I struggled to properly digest anything, even finding myself waking at night, vomiting. After many miserable years, I tried carnivore for a joke as much as anything else – I was writing a book at the time, and I thought it would make for entertaining material. I was surprised to say the least when my gut problems were resolved almost overnight. I adopted and remained on Paleomedicina’s PKD protocol for thirty months, eating only meat, salt and water. 


While that was enormously beneficial for my gut, it wasn’t entirely problem-free. One issue, which Dr Paul Saladino also experienced on a zero-carb diet, was that of chronic cramps. It didn’t seem to matter how much electrolyte I took in, how much salt or magnesium, I would wake in the night with painful cramps in my calves. I also suffered from a fast, powerful heartbeat that sometimes kept me awake. It seemed that without some periodic carbohydrates, I couldn’t properly absorb those electrolytes. I ultimately discovered that even tiny quantities of raw honey alleviated this. 


Additionally, while I went into the diet very lean, I lost weight – a lot of weight. I was strictly adhering to Paleomedicina’s quantity guidelines, which add up to a low daily intake, and it simply wasn’t enough food. As well as losing what little body fat I had started with, I began to lose lean mass as well. I felt tired, listless and cold. I didn’t feel like I was starving, I didn’t feel particularly hungry, and I experienced a degree of body dysmorphia that prevented me from seeing how emaciated I had become. It was only when I came to weigh myself that I realised that at 55kg – 120 lbs,  I was dangerously under-weight. Of course, most carnivores won’t be adhering to that very low intake guideline. Many find that they naturally eat the perfect amount, and I’m not presenting this as a criticism.


And obviously we’re here talking about fat loss, and I can attest to the fact that the satiating nature of that diet, the lack of hyperpalatable food, the low insulin – all these factors made it very easy to lose weight. The problem was that rather than a subtle calorie deficit, I had starved myself without really meaning to – I had lost my valuable muscle mass. My metabolic rate was rock bottom, and in order to fix it, I had to undergo a reverse diet – I had to prove to my brain that there was no longer the danger of scarcity. When I began to deliberately eat beyond satiety, adding in daily fresh fruit and honey to increase my appetite, I gained both muscle and fat extremely quickly. After a period of six months at a much higher level of body fat, I began to gradually reduce my energy intake, keeping protein and nutrients high, and slowly brought my body fat back down a little, while still eating twice the amount of food that I had been before. 


I remain broadly carnivore, but I now include raw honey and berries once a week, and I don’t hold back. That seems to have solved my electrolyte absorption issues, and it gives me the confidence to know that I can tolerate significant quantities of carbohydrates if I need to. It makes me more robust, more resilient in that respect. I feel like I’m full of energy, happy and healthy. I am still unable to tolerate most plant foods, but that combination of fresh fruit, honey and meat seems to be providing me with everything I need, for now. I’m open to trying anything, and while most of my attempts to reintroduce plants haven’t worked out, I’m not assuming that they can’t in the future. 


I not only had to fix my body, but also my mind – I had to deal with that body dysmorphia, to re-calibrate my perception of what a healthy human-being looks like. As we endeavour to lose fat, we must keep in mind that the images of physical perfection that we’re exposed to, the standard that the internet creates in our mind’s eye, is only achievable on a temporary basis. We can’t live at that body fat percentage for any length of time. We need to be realistic about what health looks like – it isn’t just skin and veins. 


So there are pros and cons to these very low carbohydrate diets. 


On the plus side, the removal of addictive, sweet-tasting foods, the high-protein percentage, and the nutrient density can be a superb way to correct satiety signalling. Ketogenic diets may give us a slight metabolic advantage, and for those that have begun to have blood glucose regulation problems, a very low carb approach may be the best fit – helping to regulate excessive production of insulin. 


But, as I discovered, chronically minimal insulin may make it difficult for some of us to absorb electrolytes. And by not occasionally exercising the machinery that deals with a bolus of carbohydrates, we make ourselves temporarily less able to do so, and that might represent a weakness, a chink in our metabolic armour. By completely excluding plant foods long-term, we might be making ourselves vulnerable to nutrient deficiencies, including compounds that we haven’t yet fully understood. And while these diets can regulate hormones for some of us, they can do the opposite for others – simulating a scarcity that prompts the brain to downregulate sex or thyroid hormones in response. If we’re starting from a state of ill-health, we need to find a practitioner who has clinical experience of the way these diets might alleviate or compound our particular issues. 


I’d particularly like to highlight the fact that some of these more extreme approaches can interact strongly with eating disorders. I say ‘interact’ rather than ‘exacerbate’ because some people find them very helpful, but these things must be addressed with the support of an experienced clinician. My own brush with body dysmorphia showed me how vulnerable we can be, and I was lucky to tackle that without help. If you think you might be suffering from any sort of eating disorder, however mild, get some professional advice. 


So should we be low-carb, high-carb, ketogenic, carnivore? Yes. 


If we’re healthy, we can exercise the metabolic flexibility that evolution has given us. Now when we exclude processed food and increase nutrient density, we’re going to end up broadly low-carb overall, and I’m certainly not suggesting that we include carbs in the form of nutrient-poor, energy-dense junk foods. Within the right framework, we can include the practice of eating carbs, as well as that of eating none at all. We can mimic some of the inconsistency that characterised our ancestral lifestyle. Remember that we can lose, or gain fat with or without carbohydrates. It’s all about consistently managing our calorie intake. 


We’re not looking for a diet, but a way of eating that we can adopt permanently, and the aggressive exclusion of carbohydrates long-term might not be beneficial. Let’s find what works for each of us, what best supports our goals at any given time. While that might be keto or carnivore at some stage in the process, we can play around with these approaches without dogmatically painting ourselves into corners that we feel we can’t escape should they no longer serve us. 


Our best shot at that long-term flexibility comes from understanding our own individual responses to certain foods. When it comes to fat loss, to regulating our appetite, balancing hormones, and to our health in general, we need to keep blood sugar stable. It’s therefore extremely helpful to find out how well we’re tolerating different sources of carbohydrate. In his superb book ‘Wired To Eat’, Robb Wolf establishes what he calls the ‘7 Day Carb Test’. It’s a protocol by which we can measure our own glycemic response to different foods, using a cheap, readily-available glucometer. By following this simple protocol, we can explore our individual tolerances. Either pick up a copy of Wired To Eat, or join Robb’s online community, The Healthy Rebellion. There are regular ‘Resets’ in which members can follow the protocol under guidance from the team, and there’s a fantastic community, providing both support and accountability. 


Next time, we’ll be wrapping things up with a look at exercise, fasting and the tips and tricks that might help us along the way. 


For now, keep cooking. 


Disclaimer: I am not qualified to give any sort of medical or dietary advice, and nothing in this material should be considered as such. The opinions expressed here are my own, and for the purposes of discussion only. Please consult a qualified medical professional before undertaking changes to your diet. 


Assorted Diabetes Treatment Research From Virta Health:


General information on ketosis and measurement of blood ketones:


Inuit Nutrition, Wikipedia:


Paleolithic ketogenic diet (PKD) in chronic diseases: Clinical research and data:


Anecdotal examples of the efficacy of the carnivore diet in symptom reduction and resolution:


All things carnivore with Dr Paul Saladino MD, Salty Talk 018, The Healthy Rebellion Radio:


Effects of a low carbohydrate diet on energy expenditure during weight-loss maintenance: Randomized trial:


Protein leverage and energy intake:


Effects of High Versus Low Protein Intake on Body Composition and Maximal Strength in Aspiring Female Physique Athletes Engaging in an 8-Week Resistance Training Program:


Intermittent Energy Restriction Attenuates the Loss of Fat Free Mass in Resistance Trained Individuals. A Randomized Controlled Trial:


Fast Keto with Ketogenic Girl Podcast: How to do a reverse diet: Full guide, Part 1:


The evolution of the human trophic level during the Pleistocene:


The Healthy Rebellion:


The 7 Day Carb Test:


Wired To Eat, by Robb Wolf:

Dr Georgia Ede, is a psychiatrist using diet to address various mental health issues. This site contains a wide range of articles:

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