Recently I’ve been struck by the huge discrepancy between what is advocated as a healthy, balanced diet, and what evidence actually suggests. It makes intuitive sense that the foods which are most capable of fuelling our body and supporting optimum health are those which we have been eating throughout our evolution, and this idea is supported by an ever-increasing base of evidence.
Before the agricultural revolution just ten thousand years ago (a relatively short timespan from an evolutionary perspective), our diet consisted largely of meat, fish and vegetables as well as smaller amounts of fruit (mostly berries) when in season, nuts, seeds and eggs. Though there is evidence that early humans ate small amounts of grains on occasion, this was usually a ‘starvation food’ – a last resort. Although some minor adaptations have been made since we began farming our food, these have been shown to be very minimal and a wealth of evidence now suggests that our dependence on grains is the most likely cause of the obesity epidemic, and has been linked to a whole host of other modern-day epidemics including cancer, arthritis, infertility and autoimmune dysfunction to name but a few. Fossil evidence shows that since people started farming foods and relying heavily on grains and legumes for sustenance, we have become smaller, weaker, and more prone to disease.
So where has our current conception of the optimum diet come from? The idea that we should be eating a diet which is low in fat and high in whole grains has gained popularity since the 1950s, when a number of researchers set out to prove just this. The idea that saturated fat causes heart disease for example has stemmed mostly from a single longitudinal study by Ancel Keys in 1953, called the 7 Nations Study, which claimed to show a direct correlation between dietary fat intake and the number of deaths from heart conditions. However, this was in fact a 22 country study from which just 7 were selected to support Keys’ hypothesis. The actual evidence is quite different – you don’t need to be a statistician to be shocked by the manipulation of this data set.
In contrast to the low-fat fad, there is now ample evidence to suggest that a diet high in natural fats could have far greater benefits. A meta-analysis of studies looking at 229 hunter-gatherer societies still in existence today have shown a median of 66 – 75% of calories is derived from meat and fish, and the rest from foraged plant matter. These diets have a high fat and protein intake, and the relatively low carbohydrate content is derived from it’s natural source – unprocessed vegetables as well as some seasonal fruit. These cultures have the lowest rates of diseases such as heart disease, diabetes and cancer in the world.
You might think, quite understandably, that this type of diet is only suitable for those who are constantly moving day to day – all that animal fat is high in calories, and if you’re stuck at a desk all day, you’ll end up in trouble… right? However, evidence suggests that those who eat more fat and less carbohydrate are likely to eat less overall calories, and even burn more calories without increased activity.
Our metabolism is a complex system which is affected by a number of factors aside from caloric intake, notably the ratios of calories coming from different macronutrients.
When you eat a natural diet (now referred to as being ‘high fat’ and ‘low carb’ but remember that this is relative to standard modern diets), the calories you eat are more satiating. This means that you feel less hungry and are likely to eat less throughout the course of the day. For me personally, I average around 400 – 800 calories less when I consistently eat a natural diet, with similar activity levels. This happens naturally, without going hungry in between.
What we often associate with ‘hunger’ is in fact a crash in blood sugar levels. Steep peaks and troughs in blood sugar levels caused by high carbohydrate intake mean that we need to eat every few hours to sustain energy levels, and that if we leave it a little long, we’ll naturally reach for foods which are high in simple sugars in order to bring it back up – a surefire road to weight gain. This is because most people eating a modern diet rely on glucose as their primary source of fuel. Naturally, humans burn fat as their preferred fuel source, meaning that body fat is easily converted into energy and as such we don’t get drops in energy if we skip a meal. Our ancestors would frequently go most of the day without eating, without the cognitive and physical impairments most of us would feel.
Researchers at Harvard ran a study in 2003 to look at the effects of macronutient content on weight loss. Two groups consumed the same amount of calories, but one consumed a low-fat diet and the other consumed a low-carb diet. A third group also consumed a low-carb diet but took in 300 extra calories overall. After six weeks, all three groups had lost weight; the low-fat group averaging 17 pounds, the low carb group 23 pounds and the low-carb and extra calories group lost 20 pounds. That’s not a typo. On a low-carb diet, even consuming 300 extra calories every day, weight loss was great than the low fat diet. So much for the calories in vs. calories out theory!
It’s important to note, however, that macronutrient content (the amount of protein, fat and carbohydrates we consume) is not anywhere near the full story. While important and a useful distinction, this over-simplification of dietary needs is probably the cause of so much conflicting data and controversy over low-fat versus low-carb diets. In terms of health, the nutritional values of the food we eat are crucial. It’s a shame that many people associate low-carb diets with Atkins, which an incredibly unhealthy way to eat. The differences between Atkins and a natural diet are huge. The Atkins diet makes no distinction between natural fats (such as animal fats and those contained in nuts and avocados for example) and damaging processed fats such as corn oil and vegetable oils often used for cooking. It also limits carbohydrates to such an extent that vegetable intake is limited, therefor your are unlikely to get the vitamins and minerals you need.
Natural eating was a revelation for me personally. Although I’ve always eaten ‘healthily’ in accordance with current norms and known that nutrition was important, the difference this dietary revelation has made to my life is huge. The most telling difference to me is in the way I feel. I no longer get the dreaded 4 o’clock slump. I have consistent energy throughout the day, I feel mentally clearer, I feel physically stronger, I feel more engaged and more inspired, and am able to observe relationships between my eating patterns and my moods. What’s more, rather than craving sugar, my body tells me what it really needs. Sometimes I get cravings for dark green vegetables, or carrots, or red meat. I know it sounds a little far-fetched, pining for kale and the like, but trust me it hasn’t always been that way.
I had previously seen anything which is quite restrictive as a ‘fad diet’, and not conducive to a healthy lifestyle. Most intelligent, health aware people, myself included prior to the last couple of years, will say that moderation is key, and that all you need is a balanced diet. This is certainly true, but it completely ignores the fact that moderation is a relative concept, and that the idea of balance is based on a specific balance set out by the current standard food pyramid, which goes against swathes of evidence, new and old. Paradigm shifts are often slow, particularly within the scientific community, but this one is beginning to budge.
So if you contrast the low-fat diet, high in processed foods which has been advocated based on bad science for around fifty years, and the one which is consistently associated with optimal health and lack of disease, which we’ve been eating for over two million years… which one is the fad?
Above: A more primal version of the food pyramid. Note that the ratios are based on caloric intake, rather than mass – veg should generally take up the most space on your plate!
For more information and advice, please comment with your questions (challenges welcome!) or you can email me at firstname.lastname@example.org
I would also recommend Mark Sisson’s site – he’s an advocate of primal/natural eating who is vehemently scientific and undogmatic in his approach. The best way to use the site is to type keywords into the search bar, I’d recommend starting with ‘saturated fat’, ‘grains’, ‘insulin’ and having a good read through’. There’s a wealth of evidence-based information on there.