“A low-carb diet? Isn’t that just another way to say keto?”

No. Not at all.

Do you remember when you were in grade school and learned that “all humans are mammals, but not all mammals are human?”

That’s the right way to think about low-carb diets, too:

All keto diets are low-carb diets.
But not all low-carb diets are ketogenic.
(And yes, there are many types of keto diets)

What’s the difference? Let’s dig into it.

“Low-carb” describes an overall approach to dieting, in which the consumption of carbohydrates is limited. Ketogenic eating, however, places even more serious restrictions on the amount and types of carbs you’re allowed to eat. That’s why the medical community often refers to keto as a “very-low carb” diet, instead of just calling it “low carb.”

The first thing to understand about low-carbohydrate diets is that there’s no rigorous definition for the term. Nutritionists, dietitians and doctors usually describe four general levels of carb consumption, based on the ratios of the three macronutrients in a diet (carbs, fat and protein). Here’s a summary of the most common definitions.

• High-carb: 45% or more of total calories come from carbohydrates
• Moderate-carb: 26-44% of total calories come from carbohydrates
• Low-carb: 25% or fewer of total calories come from carbohydrates
• Very low-carb: 10% or fewer of total calories come from carbohydrates

In easier-to-measure terms, that would mean a low-carb diet would contain fewer than 130 grams of carbohydrates per day, and a very-low carb diet would contain 20-50 grams per day. (1) The general recommendation for keto is on the low end of the scale, at 20 grams.

How does that match up with the normal diet? The Dietary Guidelines for Americans recommend carb intake of 45-65% of total daily calories, since dietary carbohydrates are an important energy source for the brain. (2) And a large government survey published in the Journal of the American Medical Association found that the average American currently gets about 50% of their calories from carbohydrates (the number has been trending down slowly for the last 20 years). (3) Needless to say, that’s a far cry from the 5-10% recommended for keto eating.

It might help more to look at how typical American diets match up against the 20-130 grams of carbs in very-low carb and low-carb diets. The non-profit National Academy of Medicine estimates that men usually consume between 200-330 carbs per day, while women eat between 180-230 grams each day. (4) It’s easy to see why low-carb eating requires major dietary changes.

Even those numbers don’t tell the whole story, though, because not all carbs are the same. The survey published in JAMA showed that most of the carbs Americans eat – consisting of a whopping 42% of daily calories – are “low-quality” carbohydrates supplied by refined grains or foods with added sugar. And research has repeatedly shown that low-quality carbs are associated with greater health risks, especially the development of type 2 diabetes. (5)

Low-carb diets don’t just limit total carbohydrate consumption; they encourage people to dramatically restrict the low-quality carbs in their diet. Keto diets go even further, prohibiting them completely.

Whether keto’s drastic restrictions on carb intake are necessary – and whether you’d seriously be able to stick with them – are questions that only you (and your doctor) can answer. And deciding between the two dietary approaches isn’t easy.

Some doctors recommend keto’s strict limits on carbohydrate intake for their severely obese or diabetic patients, while suggesting an easier-to-follow low-carb diet for general weight loss or overall health benefits. But there’s no definitive research comparing low-carb vs. ketogenic diets when it comes to weight loss, even though anecdotal reports indicate that keto dieters are likely to lose more weight, more quickly, over the short-term.

There’s plenty of research, however, on the medical and health benefits that these diets may provide.

Let’s first look more generally at the benefits of low-carbohydrate diets. We’ll get to benefits that are specific to keto after that.

Benefits of Low-Carb Dieting

• Low-carb diets have been proven to be a more effective weight-loss tool than low-fat diets or low-calorie eating plans over the short term (meaning a maximum of six months). (6)
• Patients on a low-carb diet have been shown to have lower triglyceride levels (7), higher HDL (“good” cholesterol) levels and lower LDL (“bad” cholesterol) levels (8), possibly because of increased consumption of healthy fats as a replacement for carbohydrates (9). Low triglycerides and improved cholesterol levels are known to lower the risk of heart disease. (10)
• Eating fewer carbs has been demonstrated to lower both blood sugar and insulin levels (11), reducing the risk of numerous medical issues including heart disease, kidney disease, and nerve problems, not to mention obesity and diabetes. (12)
• Low-carb diets have been shown effective in the treatment of high blood pressure, even allowing many patients to decrease the amount of prescription medications they take. (13)

It’s important to remember that there are many different types of low-carb diets you can follow. They range from the paleo and Atkins diets, to the South Beach and low-carb Mediterranean diets – and that’s just scratching the surface. Each provides different guidelines on carb consumption. Generally speaking, though, the fewer carbohydrates you eat, the greater improvements you’ll see in each of the health metrics discussed above.

Additional Benefits of Keto Dieting

Keto, as a very-low carb diet, provides all of the same benefits we’ve just listed. In fact, many of them are even more impressive, like greater weight loss and lower levels of cholesterol and triglycerides. But since it has the most stringent rules about carbs and macronutrients, it’s able to provide additional benefits.

The reason is simple, even though it may seem somewhat complicated at first.

As we’ve mentioned, the body normally runs on the energy generated when dietary carbohydrates are broken down. When the body has very few carbs to work with, it needs to find a different “power source” – so it breaks down stored fat to create molecules known as ketones (short for ketone bodies). When the body is using ketones instead of carbs for energy it’s said to be in a ketogenic state. Another term for it is being in ketosis.

The body is able to run fine on ketones, so once you get past an adjustment period called the keto flu (which produces side effects similar to the symptoms of the regular flu) you don’t really notice the difference – except that you start quickly losing weight as body fat is burned for energy. As long as ketone levels remain high and consistent the body remains in ketosis, and both fat-burning and weight loss continues.

Research has shown that when the body is in a state of ketosis, additional medical benefits may also follow.

• Ketosis has been demonstrated to induce changes in the metabolism, which minimize insulin resistance far beyond the effect of a standard low-carb diet. Insulin resistance is one of the primary reasons why people develop type 2 diabetes. (14)
• A form of the keto diet was first used for medical purposes in the 1920s. It was discovered to be an effective replacement for intermittent fasting, a treatment being used for some forms of childhood epilepsy which didn’t respond to conventional therapies. It was abandoned as an epilepsy treatment through much of the 20th century, but is once again being successfully used in some cases of both childhood and adult epilepsy. (15)
• Keto’s success in treating epilepsy led researchers to study the diet’s effectiveness in the treatment of other neurological diseases. To date, it has shown great promise in the management of Alzheimer’s disease, Parkinson’s disease and some types of brain tumors. (16)

It’s always difficult to choose between diets. It’s even more difficult to judge keto vs. low-carbohydrate diets which have less-stringent guidelines – until you understand what you can and can’t eat on each diet plan. We happen to have some of those specifics right here.