The Dangers of Extreme Diets

A few weeks back, me and a good friend of mine who’s quite interested in diet and exercise got to talking about the larger nutritional landscape of our society, more specifically about diets that are heavily skewed towards one food group or macronutrient, such as vegan diets, ‘the carnivore diet’, and Atkins-type diets. These diets, which to an evolution-oriented nutritionist such as myself come across as extreme, appear to have gained popularity as of late.

I find this disturbing, as there are multitudinous issues with such dietary approaches…

The rise of dietary extremism

In this day and age, there’s quite a lot of talk about our increasing consumption of fast food. Less attention has been devoted to the rise of extreme dieting.

It’s not a new thing that people are willing to go to extremes to lose weight or overcome illness; however, the recent rise of the internet, the obesity epidemic, ‘big business’, and supermarkets carrying an abundance of different foods have taken such extremity to a new level. Some of our ancestors would certainly have eaten what may be said to be extreme diets, at least periodically, but not by choice. In general, they just ate what was available to them.

Unlike them, we have access to an enormous amount of information, derived from all corners of the world, including information about different dietary trends and approaches; commonly carry a lot of excess fat around our thighs and abdomen that we’d like to get rid of, as well as suffer from many other diet-related woes that were rare or non-existent in the past; are exposed to ads and promotional campaigns featuring all sorts of nutritional products and practises; and have the option of buying and eating almost anything we like, under the constraints of our financial and geographical situation of course. This has engendered an unprecedented situation of dietary extremism.

It appears that we’re prone to thinking that if a little or some is good, then more must be better. For example, if some cutback in the carbohydrate department is desirable, then one might think that it could be even more advantageous to cut carbs altogether. Or if one supplement is perceived as beneficial, additional ones might quickly enter the mix. As I’ve talked about here on the site, I’ve previously gone to certain dietary extremes; hence, I know how easy it is to make the mistake of thinking that more is better.

Of note, it’s typically people who are already sick and physically compromised in some way who adopt extreme diets, which is worrisome, as such individuals may be less tolerant/able to offset damaging dietary effects.

Humans arguably do best on a balanced, omnivorous diet

There are so many problems with extreme diets that it’s almost difficult to know where to start. The first thing that’s important to recognize is that we humans are omnivores by nature. We’re not genetically or morphologically suited to eat exclusively plants or solely animal source foods. This is clearly reflected in research findings showing that hunter-gatherers of both the present and the past subsist(ed) on a combination of plant and animal foods (1, 2, 3). It’s evolutionarily unprecedented for a human being to only eat one of the two for a long period of time. Some hunter-gatherers, such as the Inuit, are known to have eaten a fairly extreme diet; however, these people are outliers in nutritional respects. Their diets are not representative of the type of diets that shaped the human genome over millions of years of evolutionary experience.

In a recent post, I drew attention to the fact that veganism carries with it a number of nutritional risks. It’s certainly not just vitamin B12 and high-quality protein that ‘human herbivores’ are at a risk of missing out on, but also creatine, zinc, iron, vitamin A, EPA, and DHA, to name a few important nutritional compounds. In that sense, the rise of veganism is concerning. Vegetarianism represents a notable step in the right direction, in that even the inclusion of a few types of animal source foods (e.g., eggs) can go a long way towards preventing severe nutritional deficiencies.

With that being said, it’s not any better to go to the other extreme, and almost exclusively eat meat. Actually, I’d say it’s even worse. As I was having the discussion with the friend of mine I mentioned in the beginning, we got to talking about what we’d choose if we were forced to either eat a vegan diet or a diet almost exclusively composed of animal products. We both agreed we’d rather go the vegan route. This is saying quite a bit, as we’re both very wary of the vegan MO.

One of the major issues with the carnivore approach, as well as diets low in fruits and vegetables in general, is that they throw off the acid-bace balance of the body (4, 5, 6, 7, 8). Such diets tend also to be high in salt (NaCl), which significantly exacerbates the acidity, as well as the inflammatory tone, of the situation (7, 8, 9, 10). Another big problem is the striking lack of fermentable fiber. In cases involving gut dysbiosis, this aspect of the diet is liable to calm down the gastrointestinal situation. This is easily misinterpreted as a ‘win’, when in reality it primarily reflects the fact that very little substrate is available for gut bugs to chew on. The dysbiosis is still there, it’s just no longer as strongly manifested. Top that off with the fact that people who eat extremely meaty and fatty diets don’t get to tap into the rich supply of antioxidants and micronutrients such as ascorbic acid (vitamin C), beta carotene, and potassium (which is essential with respects to counterbalancing the blood-pressure raising properties of sodium) that are found in fruits and vegetables, and one can quickly understand that it’s a fool’s errand to restrict one’s grocery shopping solely to the meat section of the supermarket. Such an approach may certainly make you thin – or at least thinner – but it’s with a high degree of certainty not going to make you healthy.

This all begs the question: Why go to extremes?

The evolutionary approach

The evolutionary approach to nutrition differs from the aforementioned approaches in that the goal is not to severely restrict the consumption of either plants or animal foods or a particular macronutrient, but rather to craft and eat a diet that agrees with our evolved biology. This is invariably going to lead to an exclusion of certain foods and food groups, simply because many modern foods differ substantially from the ones we evolved on; however, when done correctly, it’s not going to skew the diet heavily towards just one food group or macronutrient. With respect to today’s nutritional landscape and norms, it may seem extreme to cut foods such as bread and milk; however, from an evolutionary point of view, it’s today’s situation that comes across as extreme, not the one that’s existed for millions of years.

Actually, Darwinian human nutrition may be said to represent a balanced dietary approach, in that a variety of different foods, of both plant and animal origin, are propounded. There’s no inherent bias towards a particular nutrient, supplement, or food. Rather, people are advised to consume meals composed of different plant foods and animal products, thereby obtaining a balanced proportion of carbohydrate, fat, and protein.

Primary takeaway

The age-old motto that ‘it’s wise to avoid extremes’ generally holds true in dietary contexts. From an evolutionary point of view, diets that are extremely high in just one food group or nutrient come across as unsafe, in that their acid-base yielding properties, fatty acid profile, microbiota-stimulating potential, micronutrient content, and so forth deviate substantially from the type of nutritional input we’ve come to rely on to function well as a result of millions of years of evolutionary selection.