A Breakdown of Low-Carb Diets and Why They Work

What Are Carbs?

These days, it seems like everyone’s talking about carbs, particularly where diets are concerned. This is because unlike many diet fads, low-carb diets actually work. But before we delve into the world of carbohydrates and low-carb diets, let’s take a step back and look at what exactly a “carb” is.

Carbohydrates are a type of calorie-providing macronutrient, providing four calories per gram. When most people think of carbohydrates they think of breads and pastas, however, carbohydrates are found naturally in a wide variety of foods including (but unfortunately not limited to) grains, vegetables, fruits, milk, nuts, seeds, and legumes.

There are two types of carbohydrates: simple and complex. The difference here is how quickly they are digested and absorbed, which is due to the differences in chemical structure.

Simple carbohydrates, sometimes referred to as simple sugars, are absorbed quickly and thus raise blood glucose levels quickly. There are different sources of simple carbohydrates. A simple refined carbohydrate would be table sugar, while there are also natural sources of simple carbohydrates including fructose found in fruit sugar, and lactose found in milk products.

On the other hand, complex carbohydrates are starches and fibers, and take longer to digest and absorb than simple carbs due to their more complex chemical structure. Complex carbohydrates could be refined sources, such as white flour, but are also found naturally in foods like vegetables, whole grains, legumes, and nuts.

Does Science Support Low-Carb Dieting?

Calling low-carb diets a “fad” isn’t entirely accurate; yes, they’re very popular, with more and more dieters jumping on the bandwagon every day. But the idea behind these diets is founded securely in empirical fact. There is a significant amount of research pointing to the low-carb diet as the best option to treat obesity and other increasingly prevalent chronic diseases, with type-two diabetes and metabolic syndrome being at the top of that list. And, in addition to weight loss benefits, a low-carb diet also reduces blood sugar, improves blood lipid levels and blood pressure, and reduces overall inflammation which is the leading cause of so many chronic diseases and conditions seen today.

Low carb eating helps individuals lose weight and provides many other health benefits. In the past 12 years, study after study has shown that low-carb diets are effective for weight loss while also offering other health benefits. Each of these studies are randomized controlled trials (the gold standard of science) and have been published in respected, peer-reviewed journals. For example, 1 year-long study of 63 individuals placed on either a low-fat and calorie restricted diet, or low-carb diet. The low carb group lost 7.3% of total body weight, while the low-fat group only lost 4.5%, with statistically significant results. Results like these are seen time and time again. Additionally, low-carb diets are widely recognized as safe alternatives to more drastic dieting measures, with no serious side effects yet observed.

How Does a Low-Carb Diet Work?

When we consume carbohydrates, our bodies breaks them down into glucose, which is then used for energy, stored as glycogen in the liver or muscles, or converted and stored as fat. This excess fat storage contributes to risk for fatty liver and elevated blood lipids, which is harmful to our metabolic health, insulin sensitivity, glucose tolerance, and waistlines. By reducing carbohydrate intake, glycogen stores are drastically reduced, which then prevents an excess of carbohydrate being converted and stored as fat. Reducing glycogen stores is an automatic boost to initial weight loss because water is necessary to store glycogen. So, with the loss of glycogen, we lose water, making us feel slimmer and less bloated almost immediately.

Once our glycogen is depleted, the body makes a switch to begin burning fat reserves for energy rather than glycogen. However, the body will always choose to burn glycogen for energy first when it’s available, as it’s quicker and easier for the body to access. In the absence of glycogen, the body has no choice but to become a fat-burning machine. If we consumed a low-fat diet, the body would then have excess carbohydrate to store, inhibiting this fat-burning mechanism.

The Tie to Inflammation

It’s difficult to address the fat-burning and health benefits of a low-carb diet without discussing the role of insulin. Insulin is a hormone made in the pancreas that essentially shuttles the sugar (glucose) we consume and puts it to use for energy, is storage as glycogen in muscles or the liver, or is converted to fat when our carbohydrate stores (glycogen) are full. Consuming carbohydrates increases the amount of insulin our pancreas pumps out. By eating a low-carb diet, the body is required to pump out less insulin.

The less insulin our body is required to pump out, the less overall inflammation we have. Additionally, since insulin keeps fat locked into adipose tissue, lowering insulin can increase the amount of fat released to be burned for energy.

Regardless of the type of carbohydrate consumed, whether it’s fiber-rich fruits or chocolate chip cookies, insulin is still necessary. Carbs with a lower glycemic index such as tomatoes, spinach, and eggplant, for example, will require less insulin. Carbs with a higher glycemic index will cause a greater rise in blood sugar, therefore requiring more insulin. So yes, there are better choices than others when it comes to choosing carbohydrates — not all carbs are created equal. Regardless, insulin is a source of inflammation, and inflammation is a contributing factor to so many chronic diseases.

A Low-Carb Diet Makes Room for Other Important Nutrients

Additionally, cutting carbs makes room for other nutrient-dense important food groups — specifically protein and fat. Increasing protein is beneficial because protein best satiates the appetite and also increases retention of lean body mass. Protein helps to increase fat burning during weight loss, as protein has the highest thermic effect of all macronutrients, meaning it takes the most calories to digest, further increasing energy expenditure. Cutting carbs also makes more room for consuming fat, which slows gastric emptying, making us fuller for longer, and creates a platform for the body to adapt to burning fat stores rather than glycogen. A low-carb diet makes it easier for us to not overindulge in nutrient-scarce foods like breads and pastas, and instead fill up on nutrient-packed vegetables, proteins, and fats. Another major benefit of a low-carb diet is the increase in nutrient density of protein-rich and fat-rich foods.

Which Low-Carb Diet Should I Choose?

Okay, so you’ve decided to make a move towards a better lifestyle by adopting a low-carb diet. Congratulations! But with so many diets and recommendations, how do you know which direction to go? The following explains some of the most prominent low-carb diet options available, as well as the benefits, drawbacks, and  research associated with each:


  • Atkins


In a nutshell, the Atkins Diet is split into four different phases, with the initial phase strictly limiting carbs (similar to the Ketogenic Diet) and each of the following phases gradually allowing for more carbohydrates, with the goal of weight loss, followed by weight maintenance (once the ideal amount of weight loss is achieved). Research conducted at Stanford University School of Medicine concluded that the Atkins Diet led to the increased weight loss as well as cholesterol and blood pressure benefits compared to other Diets with varying carbohydrate to fat ratios.

But while the Atkins Diet may help some individuals lose weight, the truth is that Atkins is more complicated that a diet needs to be, and the allowance for carbohydrates back into the diet misses the point (and benefits) of the low carbohydrate diet completely.


  • Mediterranean


The Mediterranean Diet places a focus on healthy fats, plenty of fruits and vegetables, fish, and whole grains, while limiting processed foods and those high in saturated fats. This diet is applauded for its anti-inflammatory effects, which points to lower chronic diseases and increased longevity — two traits often associated with Mediterranean populations. However, recently it has been made public that the original research that fueled the Mediterranean Diet’s popularity may have been flawed. 

The Mediterranean diet does not dictate quantity or ratios of macronutrients to consume, and with a higher focus on plant foods and vegetables, higher carbohydrate intake is often the result. According to the Harvard T.H. Chan School of Public Health there is a risk of excess caloric intake because specific amounts of foods and portion sizes are not emphasized.


  • South Beach


Another diet that attempts to cut back on the carbs is the South Beach Diet, which promotes learning to choose the right carbs and right fats, emphasizing nutrient dense and high fiber foods like fruits, vegetables, olive oil, and avocados. But while the diet promotes healthy eating, it too is overly complicated. The South Beach Diet incorporates multiple phases of restriction and reintroduction, which more often than not results in dieters gradually easing back into old eating habits.


  • Paleo


The Paleo Diet, also known as the Caveman Diet, is based on a fairly simple premise: Only eat the kinds of things that a caveman would eat. More specifically, Paleo dieters are cautioned to shun grains, dairy, legumes, starches, and anything processed or refined. This goes a long way towards eliminating carbohydrate intake, and leaves fruits, vegetables, meat, seafood, nuts and seeds, and healthy fats from things like olive oil, coconut, or avocado as available options. There’s also generally a much less heavy emphasis on portion sizes. 

However, at its heart the Paleo diet framework is basically just an ingredient list, lacking any real insight into how much of each food item a person should be consuming. The underlying concept behind paleo is that one should eat what their genes expect them to eat. It’s lacking specificity, and lacking the correct focus as to what the body really needs. While the paleo diet has potential to be healthy, many paleo dieters end up at risk for deficiencies in calcium and vitamin D, both of which are necessary for bone health and other body functions.


  • Keto

The Ketogenic Diet is a low-carb diet best known for weight loss benefits, and it is one of the oldest and most tested clinical diet therapies, dating as far back as the 1920s (originally as a treatment for epilepsy). The modern Ketogenic Diet places heavy emphasis on healthy fats to promote the production of ketones in the liver.


Ketones are a clean source of fuel for the body and there is significant research explaining the anti-inflammatory, weight loss, and overall health benefits. When the body runs out of glycogen stores to use glucose for energy, it will turn to fat stores to burn for energy, which provides the body with ketone bodies as a fuel source. Compared to glucose, ketone bodies are a cleaner source of energy, providing decreased inflammation, improved cognitive function, and increased energy. In terms of metabolism, the body will become a fat-burning machine on a ketogenic diet if macronutrients recommendations are followed.

Generally speaking, the Keto Diet recommends intakes of 65% fat, 25 – 30% protein, and 5 – 10% carbohydrates. What is worth noting is that although the Ketogenic Diet is a low-carb diet, it is by not a no-carb diet. It is important to consume non-starchy vegetables, low carb fruits, and dairy products. If you are consuming 10% of your diet from carbohydrates, the average individual who consumes 2,000 calories per day would consume approximately 100 grams of carbohydrates daily. This is the sweet spot when it comes to losing weight, and leaves room for nutrient dense vegetables, providing necessary vitamins, minerals, and phytochemicals found in plants. That said, the Ketogenic diet also allows for regular fasting once the dieter becomes fat adapted, meaning that occasional days with 0 – 50 carb grams are also acceptable.

Keto as the King of Low-Carb Diets

The ketogenic diet is the only diet that emphasis fat as the key macronutrient, cuts carbs, and places ratio guidelines on each of the macronutrients. The ketogenic diet specifically aims to shift the body’s metabolic fuel over to burn fat by using ketone bodies as fuel rather than glucose. Also, other diets that cut carbs don’t place a limit on proteins. However, in order to lose weight most effectively on a low-carb diet and reap the benefits of ketosis, protein needs to be monitored as well. This is because certain amino acids, which are the building blocks of all proteins, are considered glucogenic, meaning that they can be converted to glucose within the body if consumed in excess and then stored as glycogen or fat. Consuming too much protein on the ketogenic diet can kick the body right out of ketosis.

How does the Ketogenic Diet Compare to Paleo and Atkins?

Keto essentially takes the concept of Paleo a step further. Like Paleo, Keto takes the concept of eating for our genes, but specifies the ingredients and macronutrients in proper amounts. And while the Atkins Diet also promotes a low-carb lifestyle, there are varying amounts of carbs required at different phases, and no specific amounts of protein or fat recommended. Keto compiles the ideas of both Atkins and Paleo but with a bit more focus and specificity to help individuals on this diet better succeed with prolonged weight loss and success on the diet.

Ketogenic Diets for the Win

Low-carb diets are an effective way to not only to lose weight, but to get you on track to a healthier lifestyle, with reduced risk of many chronic illnesses. However, the diet that takes the lead for being most effective for weight loss and overall health benefits is by far the Ketogenic Diet. Overall benefits include weight loss, decreased inflammation, and decreased risk for chronic illnesses like heart disease, diabetes, and metabolic syndrome.