Everything you think you know about low-carb diets is wrong

Disclaimer: I’m writing this post because I’ve been spending way too much time recently trying to dissuade family/friends/clients/random strangers from embarking on the latest incarnation of a low-carb diet: ‘the paleo way’ by the vibrant (of personality and skin tone) Pete Evans. 

Most Paleo advocates will try and tell you that Paleo isn’t a low-carb diet, as a completely random assortment of carb-containing foods including sweet potato (but definitely not regular potato) and certain fruits are allowed, but I’m not convinced, as you’d need to be eating a LOT of a limited number of carb-containing foods to get anywhere near 40% of your calories as carb (which is a generally accepted cut-off for a low carb diet).  If you look take a look at #paleo on Instagram, you’ll see for yourself that it’s a veritable sea of bacon, meat, coconut oil, weird things wrapped in bacon, and more coconut oil. I maintain that the *average* follower of the paleo diet is in fact, on a low-carb diet. 

Calories are supplied by the macronutrients fat, protein, carb and alcohol, and since the paleo way really emphasises the consumption of liberal quantities of meat and fish (protein and fat) and fats (such as coconut oil and avocado), this automatically drives down the amount of calories that can come from carb (as we can only eat a set number of calories each day). 

Anyway, this post was not intended to be about the paleo diet, but considering it falls under the low-carb umbrella, I guess it’s relevant to the discussion. Paleo does get a few things right, such as including loads of vegetables and fruit and dissing dairy products, but these benefits definitely don’t negate the harmful effects of such large quantities of meat and saturated fat. I’ll follow up this post with another one more specific to the paleo diet soon, but in the meantime, let’s get back to low-carb diets.

So, most people go low-carb to try and lose weight, and the elephant in the room here is that low-carb diets actually do work, and can work very well (at least in the short-term), but before you go ahead and eat the elephant, I’d like to take a look at the most common myths I hear about low-carb diets and then offer an alternative dietary solution which results in just as effective, yet more sustainable weight loss.

Myth 1: Low-carb diet started with the Atkins diet in the 1970s

Wrong. The original low-carb diet guru was one William Banting, an Englishman who lived in London during the 1800s. Originally a portly man (read: fat), Mr. Banting cut-out carbs on the advice of his physician, lost weight, and then detailed his experience in a fantastically-titled booklet named ‘Letter on Corpulence, Addressed to the public’ (1). And just like that, the first self-proclaimed nutrition expert based on their own personal experience (not formal education) was born. And they are STILL selling books. (Case in point: Sarah Wilson’s ‘I Quit Sugar’. Emphasis on the ‘I’, implying that her whole argument for quitting sugar is hinged on a sample size of one; herself). 

Anyway, there are good lessons to be learnt from Banting about low-carb diets:

1. Any form of dietary restriction will result in weight loss

In the case of Banting, he went from his usual fare of bread slathered with butter, large quantities of milk, pastries and puddings to being a Paleo pin-up boy, dining only on meat, greens, fruit and dry wine (and large quantities of alcohol, as the English love to do). Cutting out entire categories of food (in his case, anything starchy or sweet) will result in weight loss. Simple. 

But also:

2. Protein-rich foods are incredibly satiating (filling), which makes it possible to eat less calories

This guy was eating weird quantities of meat, round the clock. Breakfast, for example, was ‘beef, mutton, kidneys, fish, bacon or cold meat’ and a piece of dry toast (obviously snuck in against his physician’s orders of ‘no starch or saccharine (sugary) matter’) (1).

Myth 2: ‘Protein doesn’t cause a release of insulin. Only carbs do’ 

This is one I hear all the time. It’s thrown around in CrossFit gyms more than your average kettlebell, and unfortunately, it’s completely untrue. We’ve known for the past 50 years that eating protein-rich food, such as a piece of steak, will result in the release of insulin (2), which makes sense, given that insulin is a storage hormone, released by the pancreas to signal to the body that you’ve just eaten. Insulin causes us to store glucose as glycogen, repair and build muscle, and store fatty acids in our fat deposits. So, if you’ve just eaten a steak, you need insulin to signal to the body to take up the amino acids so they can be used to repair and build muscle tissue. There was a fantastic paper published in 1997 which showed that protein raises insulin levels just as much as carbohydrates do (3). The study looked at the insulin response to 1,000kJ (238 cal) portions of food, and found that beef (containing no carbohydrate) had a higher score than porridge, muesli and white pasta, all of which are well-known carbohydrate-rich foods.

Myth 3: But I/my sister/mother/man on television lost 3-5kg in ONE WEEK of a low carbohydrate diet!

That’s quite possible. But I’m sorry to say, this initial and rapid weight loss is not fat loss. It’s water. The body stores glucose in the form of glycogen (starch) in the liver and muscle tissue. Because of the structure of this starch, 3 grams of water molecules must be stored for every 1 gram of glucose. Given that the average person stores around a day’s worth of energy as glycogen (around 10,000kJ/2,380cals), the total weight of the stored glycogen (carbohydrate + water) is equal to around 3kg (or more, depending on your body size). As our metabolism runs on glucose, if we go on a low carbohydrate diet, our body taps into this stored glycogen for energy, which also releases the water stored alongside with it, which results in the initial, rapid weight loss.              

Myth 4: ‘If I can stay on a low-carb diet I will be thin forever!’

Unfortunately, studies show that low carbohydrate diets aren’t any more effective than low-fat diets in the long-term. Weight loss is initially more rapid on a low carbohydrate diet (for a number of reasons, discussed below), but approaches similar weight loss results by 12 months (4). 

So, aside from the water and glycogen losses of the first week, why do people get good short-term results from low carbohydrate diets?

  • There’s less choice of food to eat, which means calorie intakes are usually lower. A standard low carbohydrate diet is usually lean meat and fish, eggs, a small amount of dairy products, perhaps a small amount of fruit and unlimited low-carb veg
  • Protein makes you feel full, which means you can’t eat all that much

Weight loss does eventually plateau, probably due to people getting savvier about how to eat low carb. I mean, when you learn that you can eat start eating brownies made with almond meal and coconut oil and still be low-carbing, your weight loss is bound to stall.

 Myth 5: ‘Low-carb diets are healthy’

I disagree with this one, in a big way. With the exception of cow’s milk, all carbs in the diet come from plants, including whole grains, legumes, fruit and vegetables. These are foods we know reduce the rate of numerous cancers, heart disease and obesity. Foods that we know are good for us, as they are packed with dietary fibre, vitamins, minerals, antioxidants and powerful phytochemicals.

Animal foods (meat, fish and dairy), on the other hand, give us saturated fat, cholesterol, and pro-inflammatory arachidonic acid (omega-6) and environmental toxins, without any antioxidants or health-promoting properties.

If not low-carb, then what?

So here's the part where I offer an alternative. 

I recommend a diet based on whole, natural, plant foods, in as close to their original state as possible. 

Just whole grains, legumes, nuts, seeds, fruits and vegetables.

No added extracted oils or processed foods. Just whole foods, rich in antioxidants, phytochemicals and fibre, which our body can recognise. When we eat whole foods, we re-wire our body’s hunger and satiety (fullness) signals, which means we know when to start and stop eating, and can maintain our weight instinctually. We shouldn’t need to count calories - our body has inbuilt mechanisms to do the maths for us, but when we’re not eating the foods we were designed to eat, these mechanisms fail. It’s not our fault, it’s that we’re eating the wrong types of food - too much fat, protein and processed carbs.     

Humans are designed to eat carbs. We like eating carbs. Wouldn’t you rather wake up to a bowl of steel-cut oatmeal than a greasy plate of bacon and eggs? Carbs are our primary fuel source, and when we eat them, they are swiftly stored as glycogen in the muscle and liver, which we tap into between meals to keep our blood glucose levels stable. Yes, we need some protein in our diet (but only about 10% of our calories), and some of the essential fatty acids, omega-3 and omega-6, but carbs should really be the basis of our diet. Human civilisations have subsisted on staple foods for thousands of years, all of which are starchy carbohydrates. (Contrary to the paleo argument that we only started eating grains 10,000 years ago at the beginning of the agricultural revolution, there is very good evidence that we were eating starches well before then, perhaps as far back as 30,000 years ago (5)).  

Yes, it is true that *excess* carbs can be stored as fat (by going down a biochemical pathway called ‘de novo lipogenesis’), but it’s incredibly difficult to eat so many carbs as to fully saturate your body’s glycogen (carb) stores. Most people (perhaps excluding highly-trained athletes undergoing carb loading before a race) don’t have anywhere near the max amount of glucose in their glycogen stores, so there is little risk of converting excess carb to fat (6).

Postscript:
I asked my Mum to proof-read this post, and her only two comments were:
1. 'Gosh that Pete Evans IS handsome. Those shiny blue EYES! Perhaps eating grains [which Pete doesn't do] takes the blue-shine out of people's eyes?'
2. 'Aren't things wrapped in bacon DELICIOUS?!!' 

What a big help she is. 

References 

1.     Banting W. Letter on Corpulence, Addressed to the Public. Obes Res. 1993;1(2):153–63. 

2.     Rabinowitz D, Merimee TJ, Maffezzoli R, Burgess JA. Patterns of hormonal release after glucose, protein, and glucose plus protein. The Lancet. 1966;288(7461):454–7. 

3.     Holt SH, Miller JC, Petocz P. An insulin index of foods: the insulin demand generated by 1000-kJ portions of common foods. Am J Clin Nutr. 1997 Nov 1;66(5):1264–76. 

4.     Foster GD, Wyatt HR, Hill JO, McGuckin BG, Brill C, Mohammed BS, et al. A randomized trial of a low-carbohydrate diet for obesity. N Engl J Med. 2003;348(21):2082–90. 

5.     Revedin A, Aranguren B, Becattini R, Longo L, Marconi E, Lippi MM, et al. Thirty thousand-year-old evidence of plant food processing. Proc Natl Acad Sci. 2010;107(44):18815–9. 

6.    Acheson KJ, Schutz Y, Bessard T, Anantharaman K, Flatt JP, Jéquier E. Glycogen storage capacity and de novo lipogenesis during massive carbohydrate overfeeding in man. Am J Clin Nutr. 1988 Aug 1;48(2):240–7.