The big takeaway: A ketogenic diet is not more effective at burning fat (but it does have benefits).
On paper, the ketogenic diet seems almost too good to be true. It's built upon eating foods that are traditionally unhealthy, such as steak, bacon, and butter. The science seems good, too. If you eat more fat (and fewer carbs and protein), then your body will burn fat (instead of storing it) because you'll use fat as fuel.
If only fat loss was that simple. The claims about keto superiority for fat loss and muscle gain are exaggerated, but, that doesn’t mean the diet is without value.
As a general rule of thumb, successful diets depend on your ability to stick to a plan for a long period of time. And your adherence is determined by a variety of factors, including your lifestyle, food preferences, environment, stress, sleep, genetics, and several other factors.
Instead of trying to figure out if the ketogenic diet is better than other diets (it’s not), you should figure out how it works and if it’s a good fit for your lifestyle and goals.
How The Ketogenic Diet (Really) Works
The ketogenic diet is a low-carb diet. But, not all low-carb diets will put you into ketosis.
Roughly speaking, if you've "gone keto" then about 80 percent of your calories come from fat. The remaining 20 percent consists of protein and carbohydrates, with the most of it being protein.
When you’re in ketosis, you’ll typically eat a maximum of 20 grams of carbohydrates per day (that’s less than what you’ll find in an apple or banana).
When you cut carbs drastically -- as one does on a keto diet -- you can put your body in a state of ketosis. In this state, your liver is forced to convert fat into fatty acids and ketones — compounds your body can use to produce your body’s preferred source of energy, which is called ATP.
Through ketosis, your body becomes what many refer to as “fat adapted,” meaning your body adjusts to what you’re giving it and uses fat for energy.
In a world of quick fixes and promises, this usually is not a quick process. Research suggests that it usually takes several weeks to occur.
Remember, if you’re following a plan where you eat 50-100 grams of carbohydrates, you're still on a very low-carb diet, but it's likely that you're not in ketosis, which is the process when your body burns fat as fuel.
And don't go too crazy on the bacon and steak. Those foods are filled with protein. And – as you’ll learn – having too much protein can take your body out of ketosis.
Does Keto Burn More Fat?
When you’re on the ketogenic diet, your body is not burning more body fat.
That goes against what most people will tell you, but hang with us.
When you eat more fat -- and your body is running on fat -- your body is going to burn more fat (known as fat oxidation). Some people interpret this as an increase in fat loss, but, burning fat as fuel is not the same as burning the body fat stored in your body.
Calories still matter, and while they aren't the only thing that matter for fat loss, you still have to maintain a caloric deficit to lose fat.
So why are so many people convinced keto burns more fat?
For starters, when you cut carbs, you are likely to see some immediate changes to your weight. A lot of this is due to a shift in water weight.
But, if you want to lose fat and hold onto your muscle, research suggests that the ketogenic diet might not be ideal (it can work, but it might be more difficult). That’s because you likely need more calories coming from protein than the diet allows.
A 2015 review published in Applied Physiology, Nutrition, and Metabolism showed that to retain muscle mass while cutting calories, protein intake should be about 25 percent of total daily calories, or about 5 percent more than all of the non-fat calories allowed to stay in ketosis.
The Ketogenic Diet and Performance
If you’re looking to improve your exercise performance, the ketogenic diet comes with mixed results.
In one Nutrients study, male cyclists who followed a keto diet for four weeks decreased their body fat percentages and improved their VO2max levels (the amount of oxygen they could take in and use in a minute), but their max power decreased.
But, most research seems to indicate no performance benefit if you’re performing high-intensity activities such as sprinting and weightlifting. It’s worth noting, however, that a lot of the studies on keto done to date have suffered from at least one big design flaw.
Is It Safe For You?
For the most part, the ketogenic diet is safe. And if you struggle with a variety of health issues, it could have surprising benefits.
The ketogenic diet has a lot of fascinating research on brain health and fighting autoimmune diseases. If you struggle with a variety of diagnosed health problems, the nature of the diet is promising. And if you don’t mind the rigorous rules, it can be an effective fat loss approach – just like several other diet methods.
The catch: the ketogenic diet can be incredibly difficult to follow because of the rules and limitations on protein and carbs.
If high fat and super low carb sound easy or enjoyable, then it might be worth your time. After all, that’s the real diet secret. Research has shown over and over again that diet success depends entirely on your consistency.
Your biggest concern when considering the ketogenic diet might be protein. As we mentioned, low protein can make it hard to hold on to your lean muscle. But, if you overeat protein, then you can bump your body out of ketosis.
And, high protein intake can also increase keto dieters’ already-elevated risk of developing kidney stones. Despite many persistent myths, a high protein diet does not cause kidney problems. But, adding lots of protein to a ketogenic diet can potentially lead to kidney stones.
If you’re going to see success with the ketogenic diet, do your best to follow the rules as closely as possible, ideally under the supervision of a physician or registered dietitian. While it might not be a superior diet, it can still be beneficial and safe for many goals and lifestyles.