What’s the difference between low-carb vs. keto diets?
One of the most common misconceptions in low-carb nutrition is that a low-carbohydrate diet equals a ketogenic diet.
Though both a low-carb diet and a keto diet focus on eliminating carbohydrates, there are some important differences between low-carb and keto. And their effects on your health differ quite a bit.
Are ketone bodies essential for fat loss and overall health? Can you simply cut your carbohydrate intake without tracking and expect dramatic results?
This guide will cover the differences between low-carb and keto, plus which diet is better for weight loss, exercise performance, energy levels, mental clarity, and more.
Low-carb and keto diets share a central goal: decreasing the number of carbs you eat. Excess carbs — especially refined carbs like sugar, flour, white bread, and pasta — contribute to weight gain and a variety of chronic diseases, including:
- Type 2 diabetes
- Heart disease
- Higher insulin resistance
- Lower insulin sensitivity
- Chronic inflammation
- Digestive upsets and irregularity
- Anxiety, depression, and irritability
Both low-carb and keto diets cut out excess carbohydrate intake. But there are important differences between low-carb and keto. Let’s get into the specific definitions for each diet.
What Defines a Low-Carb Diet?
The Government Dietary Guidelines for Americans suggest that carbohydrates make up 45% to 65% of your total daily calories[*].
That means if you’re eating 2,000 calories a day, between 900 and 1,300 of those calories come from carbohydrates, or between 225 grams and 325 grams of carbohydrates a day[*].
So what does it mean to go low-carb?
There are no official guidelines for what a low-carb diet actually means as far as macro breakdown, dietary restrictions, or eating patterns.
Low-carb (also called low-carb, high-fat, or LCHF) is generally considered any diet where calories from carbs range from less than 20% of your daily calorie intake to under 45%. This translates to staying under roughly 200 grams of total carbs per day[*].
Most low-carb diets also focus on food quality, cutting out high-carb refined foods like sugar, bread, pasta, soda, high-fructose corn syrup, and baked goods. More stringent low-carb diets may cut other carbs like fruits.
But a low-carb diet doesn’t define a set number of carbs to stay under each day based on your body’s needs or goals. It gives you room to adjust your diet and find the carb intake that makes you feel best, whether that’s 80 grams of carbs a day or 200 grams of carbs a day.
Low-carbohydrate diets don’t usually recommend testing for ketone bodies — the little bundles of energy you make when you’re in fat-burning mode — or even getting into a state of ketosis.
What Defines a Keto Diet?
While a low-carb diet may not have any strict rules to follow, a ketogenic diet is defined by staying in a specific metabolic state called ketosis[*]. Ketosis requires you to eat very few carbs — usually under 50 grams a day.
In ketosis, your body doesn’t have any carbs to burn for energy, so it switches over to burning fatty acids instead.
On a keto diet, you intentionally limit your carbs to make sure your body uses fat as its primary fuel source. For most people, that means keeping your total daily carb count between 20 and 50 grams per day, and replacing the rest of your calories with fat and protein[*].
You have to be strict about carb intake on keto, because if you eat too many carbs, your metabolism will switch off fat burning and go back to using those carbs as fuel, kicking you out of ketosis.
You also want to stick to moderate protein intake, as a high-protein diet can spike your blood sugar and take you out of keto. So with a ketogenic diet, your macros are important.
Click here to find your macros using the Perfect Keto Macro Calculator!
Many ketogenic dieters also find it helpful to test their ketone levels. Testing will help you determine whether or not your body is actually in ketosis.
The dedication to cutting carbs is worth it, though, because a ketogenic diet offers unique health benefits that a low-carb diet does not.
Both low-carb and keto diets are great for weight loss[*].
However, a keto diet can make it easier for you to lose weight by keeping you full on fewer calories.
One of the side effects of ketosis is hunger suppression. Ketones control ghrelin[*] and cholecystokinin[*], two of your body’s main hunger hormones. On a ketogenic diet, you end up with long-lasting hunger suppression that makes it easier to lose weight.
In one study, 17 obese men were given either a keto diet (4% carbohydrate) or a moderately low-carb diet (35% carbohydrate), with no calorie restrictions on either diet.
The people on the keto diet[*]:
- Ate almost 300 fewer calories per day (without consciously restricting calories)
- Reported less overall hunger
- Lost more weight
Unlike the ups and downs you’ll find when you base your diet on glucose, your body can sustain itself for hours using stored body fat when you’re in ketosis. You can also combine a keto diet with intermittent fasting for even greater health and fat loss results, and you won’t feel as hungry as you would if you were eating carbs.
If you want to lose weight, a keto diet may give you an edge over a low-carb diet.
Here are just a few of the better-studied benefits of a keto diet besides easy fat loss.
Better Energy Levels on Keto (For Many People)
Keto gives you more mental and physical energy to tackle workouts, busy days, and errands with the kids.
This may be because ketones are a more efficient fuel source than glucose is — you make more ATP (cellular energy) with ketones than you do with glucose[*].
Ketones also easily cross the blood-brain barrier, your brain can use them efficiently for energy, leading to sustained mental performance and higher productivity levels.
That said, you may find you have more stable energy on a low-carb diet, especially if you work out a lot. If that’s the case, try adding some carbs back into your diet, either by going low-carb or by trying a modified version of keto like targeted keto or cyclical keto. Both are great for athletes, and still offer many of the benefits of being in ketosis.
Greater Blood Sugar Control
In a small group of obese patients with type 2 diabetes, a low-carbohydrate diet resulted in[*]:
- Participants eating fewer calories organically (by almost 1,000!)
- Around three pounds of weight loss in 14 days
- Normalized blood sugar levels
- A 75% improvement in insulin sensitivity
- Lower plasma triglyceride and cholesterol levels (by 35% and 10%, respectively)
A low-carb diet is great for managing blood sugar and type 2 diabetes. Keto seems to be even better.
In one study, 21 participants with type 2 diabetes went on a keto diet for 16 weeks. By the end of the study[*]:
- 33% of participants got off their diabetes medication entirely
- 48% of participants reduced their diabetes medication by more than half
- Fasting triglyceride levels (a risk factor for heart disease and diet-related liver damage) decreased by 42%
- Participants lost an average of 6.6% body fat
Other studies have found similar results — that keto can functionally treat type 2 diabetes in many cases, helping people get off their medication either partially or entirely[*].
Whichever diet you choose, cutting carbs will help you manage blood sugar, insulin resistance, and diabetes risk.
Better Mental Health and Cognitive Protection
Ketosis may offer long-term neurological protection against neurodegeneration and diseases such as Alzheimer’s, Parkinson’s, and epilepsy[*], while a low-carb diet may not.
The ketogenic diet was created to prevent seizures in people with epilepsy, and it’s been effective at treating drug-resistant epilepsy for more than a century[*].
Ketones are particularly good for your brain in a few different ways:
- Ketones act as antioxidants, protecting your brain cells from oxidative stress and damage[*].
- Ketosis can give you more mental energy. Keto decreases stress on mitochondria, the powerhouses that make energy in your brain. It also increases mitochondrial efficiency and overall energy production[*][*].
These mental health benefits are unique to keto; low-carb diets don’t show the same results.
But what does the evidence say about going low-carb vs. keto long-term?
While research on using a keto diet for epilepsy began back in the 1920s, it’s only now that scientists and medical experts are studying the long-term dietary preferences for a very low carb, keto lifestyle.
Keto May Help You Stay Mentally Sharp
In rodents, ketones protected against oxidative damage in several brain regions, including the hippocampus, your brain’s memory center and one of the first brain regions to deteriorate in dementia[*].
Staying keto long-term could protect your brain from mental decline and neurodegeneration, keeping you independent and mentally strong for your entire life.
Keto May Extend Your Lifespan
Being in ketosis may also extend your lifespan. Several animal studies have found that ketosis promotes longevity, and human research is underway, based on a theory that ketones alter your gene expression to slow down aging and promote a long, healthy life[*]. You can read more about ketosis and longevity here.
Other Long-Term Benefits of Keto
Current research suggests a keto diet may be more effective than low-carb diets for people managing, treating, and potentially reversing[*]:
- Type 2 diabetes
- High blood pressure
- High blood sugar levels
- Heart disease
- Polycystic ovary syndrome
- Nonalcoholic fatty liver disease
- Alzheimer’s disease
- Parkinson’s disease
- Autism spectrum disorder
The Takeaway: Keto Vs. Low-Carb
The biggest difference between keto and low-carb diets is nutritional ketosis, the metabolic state of using fat as your energy source instead of glucose.
Nutrition is personal. It depends on genetics, environmental factors, gut bacteria, and more.
Ultimately, your goal shouldn’t be to find a diet that works for everyone else; it should be to tailor your diet to your own body and figure out how to feel the best that you can.
That said, keto works for a lot of people, and because ketosis offers so many unique benefits, you owe it to yourself to try a ketogenic diet at least once.
You may find you feel better than you thought possible — or you may find you do better on a low-carb diet, or even a low-fat diet.
Regardless, it’s worth your time to experiment with keto — and with this complete beginner’s guide to a ketogenic diet, you can start keto today. Give it a try and see how you feel.