Should Low Carb be High Fat or High Protein? Zoë Harcombe

Should Low Carb be High Fat or High Protein?

Executive Summary

* This week’s note asks the question should low carb be high fat or high protein?

* Protein tends to be a fairly constant 15% of natural diets. If fat is restricted, carbohydrate increases as a proportion of the diet and vice versa.

* In his 2008 book “Trick and Treat”, Dr Barry groves included a chapter entitled “Why low-carb diets must be high-fat, not high-protein.”

* Barry’s arguments were summarised under “the case for getting energy from fat and ketones”: the fuel argument; the ketosis argument and the insulin argument. He added a fourth argument, under the heading “the case against getting energy from protein”, which was the chemical argument.

* Dr Ted Naiman presents the modern case for high protein – Drs Michael and Mary Eades and Dr Pierre Dukan have presented it previously. This note goes through Ted’s book “The P:E Diet” and presents some of his key concepts.

* Barry and Ted can both be right, as they are approaching the question of what to eat from different angles – Barry from the best way to fuel and Ted from the best way to lose weight. I think that there is an alternative approach to both of these and I present it at the end.


A couple of weeks ago, I spotted two tweets from Andreas Eenfeldt, founder and CEO of the Keto diet site Diet Doctor. The tweets said (Ref 1):

This was soon followed by an announcement that Dr Ted Naiman would be joining the Diet Doctor team to help people to “more effectively lose weight, improve your health, and improve your body composition” (Ref 2). This re-opened the question – should low carb be high fat or high protein? Let’s explore…

The macronutrient pie

I’ve had a number of penny drop moments during my many years of research. The realisation that every food that contains fat contains all three fats was one of them. The fallacy of the calorie theory was another one. So was the realisation that the demonisation of fat had inevitable consequences for the consumption of carbohydrate.

There are three macronutrients. We know them as carbohydrate, fat, and protein. If you would like to see me talk through these in a short (12 minute) presentation – it’s here (Ref 3). Some of the diagrams from that presentation are re-created below:

This is what a pie chart would look like if we consumed the three macronutrients in equal amounts, but we don’t.

Another important principle is that protein tends to be approximately 15% of any natural diet. This stays remarkably constant. There are many theoretical and empirical references for this (Ref 4). If we consumed carbohydrate and fat in equal proportions alongside a 15% natural protein intake, the chart would look like the following one. But we don’t.

The two macronutrients that are most interchangeable therefore are carbohydrate and fat. This is why – if a 30% limit is set on fat intake (as happened with the 1977 US dietary Goals), then carbohydrate becomes 55%. For the avoidance of doubt, the implication of setting a cap on fat was spelled out: “Increase carbohydrate consumption to account for 55 to 60% of calorie intake” (Ref 5).

If, alternatively, someone embarks on a very low carbohydrate diet (approximately 5% of intake as carbohydrate) – holding protein constant, fat becomes 80% of the diet. It must – it’s the inevitable consequence of slashing carbohydrate.

Should low carb be high fat or high protein?

The case for high fat

I had the honour and sadness to speak at Dr Barry Groves’ funeral in 2013. Barry was so far ahead of his time in so many nutritional fields. In his brilliant 2008 book “Trick and Treat”, Barry had a chapter entitled “Why low-carb diets must be high-fat, not high-protein.” Barry presented many arguments for this in the chapter. The first three were summarised under the sub-heading “the case for getting energy from fat and ketones”:

i) The fuel argument

Barry argued that cells derive energy from glucose, fat and/or ketones. Some cells require glucose (white blood cells and inner parts of the kidneys contain few mitochondria, red blood cells and cells of the retina, lens and cornea contain no mitochondria). Some cells prefer fat/ketones as a fuel (heart cells, for example). Some cells cannot use fats and must use glucose or ketones and will preferentially use ketones. The very limited amount of glucose that the body requires can be made internally i.e., we don’t need to consume any glucose. The process by which glucose is made is called gluco-neo-genesis, which literally means glucose-new-birth.

Barry noted that our bodies need approximately 1-1.5 grams of protein per kg of lean body weight per day. Any protein intake above this can be used by the body as a source of glucose. This process is very inefficient, which is poor for fueling but inefficiency of food intake is good for weight loss (we’ll come back to this).

ii) The ketosis argument

Barry argued that the state of ketosis requires substantial reduction in carbohydrate and replacement of that lost energy with fat, not protein. Two short statements in this chapter are key:

“Reduction of carbohydrate intake stimulates the synthesis of ketones from body fat.”

“Fats produce an important secondary fuel called ‘ketone bodies.’”

Barry also noted that a shift to fueling on fat, with accompanying ketone formation, reduces the body’s overall need for glucose as cells that can fuel on fat/ketones will do so. “As the level of ketones in the blood reaches about 8 mmol/L, some 75% of our bodies’ glucose requirement can be replaced by ketones. This significantly reduces the conversion of tissue protein into glucose, resulting in a substantial reduction of muscle loss.”

Consuming protein in preference to fat can impact achieving and maintaining ketosis.

iii) The insulin argument

Of the three macronutrients, carbohydrate is the one that impacts blood glucose levels. Carbohydrate and protein impact insulin (the protein impact is small compared to carbohydrate but must not be ignored). Fat has negligible impact on either blood glucose levels or insulin. It is the safest macronutrient to consume for avoidance or management of diabetes and/or metabolic syndrome.

The final argument was presented under the sub-heading “the case against getting energy from protein”:

iv) The chemical argument

Barry explained that carbohydrates and fat are made up of just three elements: carbon, hydrogen and oxygen. Proteins also contain nitrogen and other elements. When proteins are used to provide energy (broken down) these must be disposed of in some way. Barry argued that this is wasteful and it can put a strain on the organs responsible for this (kidney and liver). Protein also requires fat-soluble vitamin A for its metabolism. “A diet too high in protein without adequate fat rapidly depletes vitamin A stores, leading to serious consequences such as heart arrhythmias, kidney problems, auto-immune disease and thyroid disorders.”

The case for high protein

Ted presents his argument in his book “The P:E Diet – Leverage your biology to achieve optimal health.” The book is pictorial rather than wordy. It’s more like going through a presentation, than a book. It would have taken a lot of effort to assemble and it’s an impressive piece of work (Ref 6).

Before we turn to Ted’s work, it’s worth noting that high protein diets are by no means new. Drs Michael and Mary Eades wrote “Protein Power”, which was first published in 1996. Michael is still a superpower on the low carb speaker circuit. The Dukan Diet, written by Dr Pierre Dukan, was published in 2000. The ‘attack’ phase of The Dukan Diet allowed only high protein foods – lean meat, skinless poultry, fish, eggs, and non-fat dairy products. Not even green vegetables are consumed in the first phase. The next phase adds non-starchy vegetables – big deal! Protein Power was much more sensible – embracing, but not overdoing, natural fats.

Ted sets out how to lose weight early on in his book (p18):

“If you want your body to be better at burning fat, you only have to do one thing: Eat fewer carbohydrates.”

“If you want your body to be better at burning its own stored body fat, you only have to do two things: Eat fewer carbohydrates, and then eat less fat.”

Ted’s three pillars of his approach are:

1) Increase protein percentage.

2) Decrease carbohydrate frequency.

3) Avoid high carb + high fat (which was one of the founding principles in my first book in 2004).

Ted explains that “everyone is eating enough protein. That’s not the point. The point is – how much energy did you have to eat to get that protein?” (p42) That’s where I started to question things, as it doesn’t take much energy to meet one’s protein requirements. For example, I’m 49kg. My protein requirement is 49-73g per day. I could get 26g of complete protein, for 116 calories, in 100g of canned tuna (Ref 7). I could eat 300g of tuna and get 78g of protein (beyond any upper limit) for 348 calories.

Ted’s key chart is this one:

Ted defines his P:E (protein to energy) ratio as protein (in grams) / (fat + carbs – fiber) all in grams (p110). Ted says that this can also be written as protein (g) / (fat + net carbs) (in grams). (As a quick aside here, I’m not a fan of net carbs. I’m in the Dr Eric Westman school on net carbs – if you need to count carbs, you need to count carbs!) The book gives plenty of examples of how to calculate the P:E ratio. E.g., a nutrition label for pasta is shown on p114. This lists, per 57g serving size, protein as 5g, fat as 2g, carbohydrate as 43g and fiber as 2g.

The P:E ratio is then 5 / (2 + 43 – 2) = 5/43 = 0.12.

Ted says “you want to INCREASE your current protein to energy ratio in order to increase the protein to energy ratio of your body. A good target might be 1.0, which is roughly equal grams of protein and non-protein energy” (p112). Pasta is thus a poor choice, as 0.12 is well below 1.0.

The example for extra lean ground beef on p115 shows that, per 100g, there are 21g of protein, 10g of fat and 0g of carbohydrate or fiber. The P:E ratio is thus 21/10 = 2.1. That’s a good choice in Ted’s plan.

Strictly speaking this should be a protein to weight ratio (P:W), as it’s all in grams. If the grams were converted to energy, in the ground beef example, 21g of protein would contain approximately 84 calories and 10 grams of fat would contain approximately 90 calories. If all macronutrients were viewed in energy terms, this ratio would be 84/90 = 0.93. If protein were kept in grams (as the P part of the ratio) and the bottom part of the ratio really was energy (E), then the lean beef example would be 21 (g) / 90 (cals) = 0.23. Just saying!

That notwithstanding, if we do go with Ted’s P:E ratio as called and defined, as you can see from the diagram, good and bad foods are easy to categorise. Sugar and vegetable/seed oils (zero protein) are the worst things to consume. I agree. But at the other end of the scale, whey protein and eggs whites are the best things to consume. I disagree. The main reason for eating, in my view, is to obtain the nutrients that the body requires (complete protein yes, but also essential fats, vitamins and minerals). Whey protein and egg whites tick the protein box, but not much else.

Ted’s diagram rightly puts flour, whole grains, and potatoes on the ‘not-so-good’ end of the scale. More controversial would be the placing of nuts and peanuts at this end of the scale. I support Ted on this, as I questioned the virtue of nuts and seeds in my first (2004) book when I pointed out that they were unique natural foods in being high in both fat and carbohydrate. Ribeye steak, eggs, soy/tofu are placed on the P:E ratio of 1.0 on the diagram. Soy/tofu (plant sources) are not as good in protein quality as meat and eggs (animal sources). Cheese and milk are below the 1.0 line on Ted’s diagram. They are excellent sources of nutrients. Ground beef, pork, chicken breast (skinless no doubt), fish (white no doubt), plain non-fat yoghurt, green and cruciferous vegetables, are all above the P:E ratio of 1.0. These are good foods, but oily fish is more nutritious than white, red meat is more nutritious than white, and full fat dairy is more nutritious than low fat.

There are some sound judgements in the diagram, but I struggle to approve overall of any scale that places egg whites as better than the whole egg, or the yolks.

Barry vs Ted

This doesn’t need to be a fight. Both can be right and I think both are – with a key caveat. Barry was primarily writing about the optimal way to fuel. Ted is primarily presenting the optimal way to lose weight. Barry was right that the body wants fat rather than protein to fuel. Ted is right that protein has advantages when it comes to weight loss. (Both would no doubt agree with the other’s contribution).

Ted and Barry would agree that using protein for fuel is inefficient. The work of Luc Tappy established that: “Measured thermic effects of nutrient are 0-3% for fat, 5-10% for carbohydrates and 20-30% for proteins” (Ref 8). This means that, if we consume 100 calories of pure fat, approximately 97-100 will be available to the body. If we consume 100 calories of pure carbohydrate, approximately 90-95 will be available to the body. If we consume 100 calories of protein, approximately 70-80 will be available to the body. That’s a significant metabolic advantage in favour of protein (and body builders know this).

However, I would approach what to eat differently to both of them. I maintain that the best general eating principles are: 1) Eat real food; 2) Choose that food for the nutrients it provides; 3) Eat a maximum of three times a day (Ref 9). Barry and Ted would agree on real food. Barry would then prioritise fat and Ted would prioritise protein, but neither approach optimises nutrition – which should be the main reason for eating. The most nutritious foods are red meat and offal (more than white meat, but white meat is better than starchy stuff), oily fish (more than white fish, but any fish is better than starchy stuff), whole eggs, full-fat dairy and non-starchy vegetables.

Butter, loved by proponents of LCHF, is actually not that nutritious. Egg whites and whey protein, loved by proponents of LCHP, are actually not that nutritious. Barry’s approach (LCHF) risks people doing what I have seen them do at low carb conferences – adding butter to meat and vegetables ‘to try to get their fat intake up’. (This is fine if you’re slim and active, but if you want to burn body fat don’t add butter or you’ll burn that instead.) Ted’s approach (LCHP) risks people doing seriously stupid things, like consuming an egg white omelet.

In this 2017 post, I examined the so-called “The Optimal Diet.” This was the work of a Polish doctor called Jan Kwasniewski (Ref 10). This diet worked out the ideal protein intake from due body weight (what you should weigh, not what you might weigh currently) and then calculated the fat and carb intake that should accompany this protein intake. A small range was allowed, for different activity levels. As proportions of the diet, the lower fat intake worked out at 14% protein, 79% fat and 7% carbohydrate. The higher fat intake worked out at 11% protein, 84% fat and 5% carbohydrate.

I devised a one-day eating plan that would meet the requirements of the lower fat option for The Optimal Diet. It required 90g of butter – the single biggest calorie intake (645 calories) from any food for the day. Butter has some vitamin A and E but not much else of note. If we’re trying to get the nutritional ‘bang for the buck’ – the most nutrients for the fewest calories, we should be eating liver, not butter. If we delete the butter from that example day’s eating, the macronutrient ratios become 11% carbohydrate, 66% fat and 23% protein. But the daily calorie intake drops to nearer 1,000, so the consumer could add liver, oily fish, dairy products and other highly nutritious foods and eat even better for a typical day.

The principles of 1) Eat real food; and 2) Choose that food for the nutrients it provides, lead naturally to a low carb diet and then the fat and protein will be what they will be. Should low carb be high protein or high fat? It should be what it will be!

Until the next time

All the best – Zoë


Ref 1:

Ref 2:
Ref 3:
Ref 4: Here are my favourite two:
Theoretical: Gordon Wardlaw, Smith. A. Contemporary Nutrition. Seventh edition ed: McGraw Hill; 2009 10 February 2008.
Empirical: Dehghan et al. Associations of fats and carbohydrate intake with cardiovascular disease and mortality in 18 countries from five continents (PURE): a prospective cohort study. The Lancet. 2017.
Ref 5: Carter J.P. Eating in America; Dietary Goals for the United States; Report of the Select Committee on Nutrition and Human Needs US Senate. Cambridge, MA, USA: MIT Press 1977.
Ref 6:
Ref 7:
Ref 8: Tappy L. Thermic effect of food and sympathetic nervous system activity in humans. Reprod Nutr Dev 1996
Ref 9: Dr Zoë Harcombe. The Diet Fix. Published by Short Books. 2019.
Ref 10:

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