Low Carb Diet: What is it and How it works

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Conventional wisdom has it that carbs, especially complex ones originating from grains and fructose from fruit, should be a cornerstone of everyone’s diet. That’s the reason low fat diets became popular in  the ’70s. Since then, we have seen a rise in obesity worldwide, especially in children, and other obesity-related health problems; we can safely assume that many of those problems are connected to our modern diets. In recent years, the low fat myth has been debunked and low carb diets have started becoming more and more popular.

An effective diet should achieve two things for you: bring about weight loss by improving insulin sensitivity, and lower inflammation, speculated to be main culprit for almost all modern diseases, including cancer, Alzheimer’s and depression. Some level of inflammation is necessary for our body to fight foreign substances and microbes, and we all have low-grade inflammation waging in us at all times, but the problem is when inflammatory response becomes chronic. [1]

So, let’s see what the science behind low carb diets exactly is and how they work, what types of diets there are, and how to make them work for you.

Some may argue that the reason low carb diets work is because instead of eating highly processed food products, you start eating less processed – and healthier – ones. While that does hold some truth, the main argument supporting a low carb diet is that cutting out carbs (even the complex ones like grains, potatoes, rice, beans and fruit) and simple sugars will improve the way your cell receptors react to insulin, a hormone responsible for getting glucose into cells and turning it into energy.

When you eat a lot of carbs (or mainly carbs), insulin receptors become less responsive to glucose and get overworked, so eventually they start refusing to take the glucose into the cell. This is called insulin resistance. What happens to your body when there is insulin resistance? You start feeling less energized (because there is no glucose being taken into your cells and  muscles), you are sleepy more often, your mood starts to decline, your acne flares up (there is a positive link between insulin and androgens – ’male hormones’) and you might even become chronically tired or depressed. Do this long enough, say 15 years, and you might even get diabetes.


Source: https://blog.glycoleap.com/types-of-fat/


You might ask, then what am I supposed to eat? Well, protein and fat. Contrary to popular belief, fat isn’t always bad. It depends on what kind of fat you consume, because that’s what could cause inflammation. There are four types of dietary fats: trans fats, the worst kind of fat, found in margarine and hydrogenated vegetable oils; saturated fats, such as bacon grease, whole milk, coconut oil – everyone’s biggest fear is that saturated fat will clog the arteries, but there is not enough evidence to conclude that saturated fat increases the risk of heart disease[2]; monounsaturated fats, found in olive oil, avocados, and most nuts; and polyunsaturated fats – these are omega-3 found predominantly in fish (the fattier, the better) and are anti-inflammatory, and pro-inflammatory omega-6s fats (although some omega-6s, such as evening primrose oil, can be anti-inflammatory).

But, wouldn’t simple calorie restriction do the job? Well, yes and no. While calorie restriction has been linked to numerous health benefits that stem from weight loss, such as better mobility, improved biomarkers associated with aging[3], a longer lifespan and less oxidative stress, eating too many carbs will still keep you in a hectic insulin response cycle. Additionally, you might still be bombarding your body with pro-inflammatory fats and depriving yourself of nutrients even while staying within a low calorie range. By eliminating most of the carbs, you eliminate most of the sources of inflammation and also stabilize your insulin by making your body rely on protein and fat for energy.

Diets low in carbohydrates

If you are still scared of consuming fat and think that it shouldn’t take up more than 20% of your daily calorie intake, then there are several ways to follow a low carb diet. The following diets are examples that you could implement.

Mediterranean diet

A lot of doctors and health advisors love and endorse the Mediterranean diet. It is the simplest version of low carb eating, but it does have some shortcomings – whole grains for example. Whole grains can be as inflammatory as refined grains are. [4] Also, unlimited fruit consumption may be a problem, since fructose contributes to fatty liver. Other than that, this diet is packed with fish, olive oil, vegetables, seafood and nuts, which all contribute to optimal cardiovascular health.

LCHF (low carb high fat)

While with the Mediterranean diet most of your calories should come from vegetables, olive oil and lean sources of protein, the LCHF diet’s primary energy source is fat, not protein. Protein can turn into glucose, via the process called gluconeogenesis, and spike insulin. Fat is the only macro-nutrient that cannot be turned into glucose, therefore consumption of dietary fat does not lead to weight gain.

Primal diet

The primal diet or primal blueprint diet was created by Mark Sisson (Mark’s Daily Apple). Its philosophy is based on allowing only food our early ancestors would eat and have access to. That includes berries, for example, but excludes grains. Take note that berries are of significantly lower glycemic index than today’s fruit. What about bananas, then? We didn’t have access to all food groups year-round, and not all geographic regions would have had the same food available. Sugary fruit naturally occurs in warmer parts of the world, where there is less meat; while the colder parts of the Earth have more meat, but don’t have bananas, coconuts and pineapples. The premise is that you should eat seasonally, but also regionally.

 Ketogenic diet

The ketogenic diet is a pretty straight-forward, strict diet. The goal is to stay under 20 grams of net carbs (amount of carbs after you subtract indigestible fiber in vegetables and sugar alcohols from total carb amount) so the process of ketosis can begin. It is a metabolic state in which the body starts breaking down your fat reserves and starts using ketones, a by-product of fat breakage, for energy. Your glycogen (sugar stored in liver) starts depleting, you lose a lot of water weight initially, and then the real journey begins. You need at least two weeks to become keto-adapted or metabolically flexible (to use fat as energy effectively). There is a lot of science to back up the ketogenic way of eating. Anecdotal evidence suggests that the diet helps insomnia, soothes mental health problems, boosts athletic performance and completely curbs cravings, which is a prerequisite to a successful diet.

Zero carb

The zero carbs diet is sustainable only for dedicated lovers of this lifestyle. It is even stricter than the ketogenic diet and allows no carbs, not even from plant sources. Because it’s impossible to eat vegetables and ingest no carbs, followers of this diet do not consume vegetables, so the diet is also called carnivorous, hunter-gatherer or indigenous diet. Not eating vegetables may sound terribly wrong, but there is evidence that suggests that the Inuit, who traditionally ate only meat due to scarcity of other food, are among the healthiest people on the planet. It is called The Inuit paradox.[5] What about vitamins or scurvy? The argument is that meat has all the vitamins you need if you eat all its parts, including liver (high in vitamin A) and adrenal glands (because they store vitamin C). Some go even further and eat raw meat, but let’s leave that for some other time.


[1] https://www.health.harvard.edu/newsletter_article/Inflammation_A_unifying_theory_of_disease

[2] https://www.ncbi.nlm.nih.gov/pubmed/20071648

[3] https://www.ncbi.nlm.nih.gov/pubmed/29576535

[4] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2821887/

[5] https://facweb.northseattle.edu/ccummings/Cultural%20Anthropology/The%20Inuit%20Paradox.pdf

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Marija Melentijevic has a master's degree in international relations and feels very passionate about political theory and philosophy. She is very passionate about all things health, but especially the way food choices affect our health, our evolutionary adaptations to some food, and how we should eat so we can achieve an optimal level of mental and physical performance. She is From Serbia.
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