There’s a seemingly never-ending debate about the “best” diet for weight loss. Most would agree there is more than one way to peel an orange. Yet, with its recent rise in popularity, the keto diet has emerged in many circles as a frontrunner. The attention the keto diet has garnered has spurred quite a bit of revealing research and heated debate.
Is the keto diet just another synonym for hype? Or, is the keto diet actually good for weight loss?
Let’s see what the science says…
Is the Keto Diet Good for Weight Loss? Here are 4 Separate Studies
Simply put, there’s no shortage of strong evidence that a keto diet works for weight loss. Even more, there’s good reason to believe it’s as effective—if not more so—than traditional weight-loss diets.
Let’s look at a randomized controlled trial published in the journal Endocrine. Researchers from Spain found obese participants following a keto diet for just two months lost nearly 30 pounds. During the same time, participants following a standard low-calorie diet lost just 10 ½ pounds. 1
After 12 months, 88% of the keto dieters had lost more than 10% of their initial starting weight. Plus, they maintained nearly 3 times more weight loss than the low-calorie group.
This is a key finding because research suggests many obesity-related conditions improve with modest weight loss (i.e., 5 – 10%). This can include high blood lipids, high blood pressure, diabetes, insulin resistance, sleep apnea, inflammation, cardiovascular disease risk, and more. 2,3
Take a look at another study published in The American Journal of Clinical Nutrition. Researchers found obese men following the ketogenic diet for 4 weeks lost nearly 14 pounds. These were 46% better results than a group eating a “moderate” carbohydrate diet. 4
One particularly compelling facet of this study was that calories were not actively restricted. In other words, the keto diet naturally lowered hunger and food intake. Worth mentioning, however, was that the keto diet used in this study was higher in protein (30% of calories) than the typical keto diet (15 – 20% of calories). And, it’s well-known that higher-protein diets are quite effective when it comes to appetite management.
In a study published in the journal Nutrition & Diabetes, 89 men and women, between 30 and 65 years old, with type 2 diabetes (T2D) were randomly assigned to a very-low-calorie ketogenic diet (VLCK) or a standard low-calorie diet based on the guidelines provided by the American Diabetes Association. 5
At the end of the 4-month trial, the keto diet group experienced significantly greater weight loss. They also lost more inches from their waistlines and experienced better improvements in blood glucose levels (HbA1c) and glycemic control compared to the standard dieting group.
The researchers concluded, “A VLCK diet is most effective in reducing body weight and improvement of glycemic control than a standard hypocaloric diet with safety and good tolerance for T2D patients.”
By the end of the study, 98% of the keto diet group experienced 5% weight loss while 85% of the group dropped 10% of their initial weight. In contrast, 50% and 17% of the standard low-calorie group lost 5% and 10% of their starting weight, respectively.
A couple important points about this study, however. During the “active phase” of the keto diet, participants ate mostly prepared meals. Their calories were also limited to just 600 – 800 per day. This active phase was maintained until the participants lost most of the weight-loss target, ideally 90%. On the other hand, the standard low-calorie diet simply restricted calories by 500 – 1,000 calories per day.
It’s quite possible this protocol tipped the figurative scale in favor of the keto diet. And while that may indeed be the case, this same very-low-calorie keto diet protocol has been shown to be a very useful and effective tool for weight loss while reducing belly fat, preserving muscle mass and strength, improving metabolic profile and markers of inflammation, reducing food and alcohol cravings, improving physical and sexual activity, reducing sleepiness, and enhancing overall quality of life. 6,7,8
Yet, perhaps most striking are the results from two separate systematic reviews. These arguably represent the most critical assessment on the topic.
In a meta-analysis of randomized controlled trials published in the British Journal of Nutrition, Brazilian researchers concluded, “Individuals assigned to a VLCKD [keto diet] achieve a greater weight loss than those assigned to a [conventional low-fat diet] in the long-term; hence, a VLCKD may be an alternative tool against obesity.” 12
In a meta-analysis published in The Lancet, a panel of researchers from Harvard Medical School concluded, “In weight loss trials, higher-fat weight loss interventions led to significantly greater weight loss than low-fat interventions.” 13 Full disclosure, unlike the above review study, not all the studies included in this analysis tested the keto diet.
What about when you add exercise to the equation? After all, it’s one of the most powerful tools for improving carbohydrate metabolism and metabolic health.
Several studies have shown that combining weightlifting with the ketogenic diet results in impressive changes in body composition (including significant reductions in body fat) when compared to a standard Western-style diet. 14,15,16,17
Now, you could certainly make the argument that a noteworthy body of the research is not comparing apples to apples. For example, comparing a very-low-calorie diet (regardless of macronutrient composition) to a low-calorie diet is bound to yield more favorable weight-loss results than the latter. Likewise, it’s not hard to believe that the keto diet is superior to the Standard American Diet.
Having said that, there’s no shortage of evidence demonstrating the effectiveness of the keto diet for weight loss. In other words, the keto diet is actually good for weight loss..
Why Does the Keto Diet Work for Weight Loss?
When it comes to weight loss, the ketogenic diet works very well. So, how exactly does it work? Great question!
The answer is that it depends on who you ask. I know, how boring is that?
Some will be quick to tell you that the ketogenic diet provides a “metabolic advantage.” Briefly, proponents of this theory say that, calorie for calorie, the keto diet leads to more weight loss than other types of diets (containing carbs) because it somehow forces the body to burn more calories. In essence, this view refutes the second law of thermodynamics and the notion that a “calorie is a calorie.”
This follows closely with the “carbohydrate-insulin model of obesity,” which states that diets high in carbohydrates are particularly fattening because they elevate the hormone insulin, which in turn increases fat storage and decreases fat burning. Proponents argue that this leaves you in a perceived state of starvation, which reduces calorie burning and drives food intake.
On the other hand, swapping carbs for fat, such as the case with the keto diet (which severely restricts carbohydrate and very effectively lowers insulin levels), is thought to work by increasing calorie expenditure, increasing fat burning, and reducing fat storage. Pure magic!
As exciting and alluring as that sounds, it doesn’t seem to stand up to the scientific burden of proof. However, a series of recent very well-controlled studies conducted by Dr. Kevin Hall and his team of researchers at the National Institutes of Health have provided evidence falsifying the carbohydrate-insulin obesity model. 18,19,20 In other words, there doesn’t appear to be any “metabolic advantage” with the keto diet.
How Does the Keto Diet Work?
Be that as it may, it’s undeniable that the keto diet is effective for weight loss. That brings us back to the original question…how does it work?
According to Dr. Antonio Paoli, who’s an author of several published studies and review papers on the keto diet, a “simpler, perhaps more likely, explanation for improved weight loss is a possible appetite-suppressant action of ketosis.” 21
Indeed, a recent review study published in the journal Obesity Reviews found exactly that. The keto diet suppresses appetite, reduces hunger, and increases satiety (feelings of fullness and satisfaction). 22 Additional studies have shown the ketogenic diet reduces levels of the “hunger hormone” ghrelin and increases levels of satiety hormones, such as CCK. 23
Cravings & Ketones
You see, the keto diet may flex its weight-loss muscle through elevated levels of ketone bodies, believed to have direct appetite-suppressant properties. In fact, ketosis is thought to be a key factor in the effectiveness of very-low-energy diets (VLED, ≤ 800 calories/day). Of course, these represent the most intensive and single most effective dietary intervention for rapid initial weight loss and reducing obesity. 24
Despite severe caloric restriction and rapid weight loss, VLEDs often don’t lead to a compensatory increase in hunger. In fact, folks who follow VLEDs are actually less hungry and experience greater fullness and satisfaction (i.e., satiety) compared to when they are in energy balance before the diet. Researchers attribute these surprising benefits to higher levels of ketones with VLEDs. 25
While both induce ketosis, the ketogenic diet results in several-fold higher levels of blood ketones compared to VLEDs. This is why one of the reasons the keto diet works so well for weight loss. Suppressing the drive to eat results in spontaneous reduction in food intake.
Along those lines, studies report that folks who follow a keto diet for weight loss report feeling less hungry with a reduced desire to eat. 22
This explanation is key. It’s arguably more important than metabolic advantage. How many times have you started a diet only to give up due to uncontrollable hunger and cravings? Probably more times than you’d like to admit.
Typically, when you reduce calories and lose weight, the body fights back ferociously by increasing hunger hormones and reducing satiety hormones. We’re programmed to combat starvation, pushing us to overeat, especially high-calorie, tasty foods. This is all part of a compensatory process called adaptive thermogenesis.
The ketogenic diet, in contrast, has been shown to prevent an increase in appetite despite weight loss. One recent study found in the International Journal of Obesity showed that, like any diet, the early stages of the ketogenic diet can lead to increased hunger. Yet, after just a couple weeks, appetite is regulated and hunger is suppressed—despite continued weight loss. 26 As you might have guessed, this has healthy implications for long-term weight loss and maintenance.
In other words, it appears the ketogenic diet suppresses the typical compensatory increase in the drive to eat in response to caloric restriction and weight loss. And it seems plausible that ketosis and elevated levels of blood ketones may be to thank due to the appetite-suppressing qualities.
How Else Does the Keto Diet Promote Weight Loss?
From a practical standpoint, many (including even the staunchest keto advocates) trace the effectiveness (and benefits) back to RULES. You see, people like to be told what to do. They like guidelines and boundaries. They like some sort of standard up to which they can compare themselves. We want to know where we’re at. We want to know how we’re doing.
And the rules of keto do just that. Limit carbs to 30 grams per day (give or take). Simple as that. Of course, the ketogenic diet is far more complex than that. But from a figurative 1000-foot view, this is THE rule.
And when someone follows that rule, the menu of food options gets limited tremendously. You take a ton of ultra-processed, calorie-dense, highly-palatable “foods” off the table. And when you do that consistently over time, voilà! The keto diet can be tremendously effective for weight loss and lead to improvements in virtually all aspects of life and health.
This highlights the significance of your food environment. When you’re committed to the rules, you make sure there aren’t foods that are “out of bounds” at home (to tempt you). And you do your homework to make the appropriate choices when you’re out of the friendly confines of your own home.
Another reason the keto diet can be useful for weight loss is the buy-in. Up until now, it’s been an outside-the-box approach. Before, people kind of looked at you like you had a third eye if you told them you were keto.
Now that the keto diet is so popular for weight loss, that means other people are doing it, and that means there’s positive social support and accountability. And those, my friend, are critical elements to success. If you’re keto, you’re not the elephant in the room. You’re “normal,” and that makes everything easier.
All that being said, as straightforward and “simple” as the rule(s) may be, that doesn’t make keto any easier (to follow) than any other weight-loss diet. Along those lines, some experts argue that it’s so extreme that it bears being ranked dead last among the US News and World Reports’ list of best diets. 27
Despite its restrictive nature, however, research doesn’t seem to corroborate that scarlet letter. In other words, studies show that adherence to the keto diet for weight loss isn’t any worse than a low-fat diet.
In fact, some studies have shown the exact opposite. And when it comes to weight-loss success, adherence is king. At the end of the day, you have to find what works best for you.
Keto Diet Beyond Weight Loss
Now, if you’re interested in digging deeper into the keto diet for weight loss, overall health, or just in general, we have no shortage of resources for you between our 5-star-rated podcast and blog. Here are some of our top recommendations:
- Death to Keto – In this podcast, we discuss how keto is just one of many tools in the figurative toolbox. We also reveal 5 dietary strategies we believe everyone should be taking first—before even trying Keto.
- The ABCs of the Keto Diet – In this podcast, we package three of our most popular keto episodes into a single information-packed podcast covering the nuts and bolts, including how to optimize the keto diet for weight loss, dispelling myths and misconceptions, and more.
- Is the Keto Diet Safe? Get All the Facts Here… – If you have concerns about using the keto diet for weight loss, then you’ll want to check out this article where we discuss (and dispel) many of the myths and misconceptions about keto.