Q: Will taking ketone supplements, while eating a normal diet, provide the same fat-loss benefits as being on a seriously carb-restricted, or ketogenic diet?
The very short answer to your question is "probably not," but given how complex the burgeoning field of study into nutritional ketosis is, that simple answer requires a bit of unpacking.
The basic thinking when it comes to supplementing with ketones and their effect on fat loss is this: When your body is consistently carb-depleted, it produces ketones as a mechanism to utilize fat (and to a lesser extent, amino acids from muscle) as fuel. These ketones can also be used as an alternative to glucose as fuel to support your brain, muscles, heart, and other organs. Once you have a high enough presence of ketones in the blood, usually around 0.5 to 3.0 mM per deciliter of blood (as can be measured with urinalysis ketone strips), you have entered what is known as "nutritional ketosis." To be clear, your body is what is producing those ketones, though.
Ketone supplement advocates extend that line of thinking beyond the ketones your body is manufacturing on its own. Their case is that if consuming a ketone supplement raises your blood ketone level to the point where you are technically in ketosis, then you must be burning fat with the same effectiveness if you came by your ketosis the old-fashioned way.
Unfortunately, the scant scientific evidence that currently exists doesn't support connecting the dots this way. Researchers out of the University of Sao Paulo, in Brazil, recently gave a group of rats substantial doses of beta hydroxybutyrate (exogenous ketones) both acutely and for four weeks. Not surprisingly, the researchers concluded that consuming oral ketones increased circulating ketones (ketonemia). To which I say: big deal. Consume a bunch of fat and you'll see free fatty acids in circulation, too. That marker alone doesn't mean that you're burning more stored body fat.
Likewise, the researchers didn't show a drop in glucose or insulin, and it's the combined rise in ketones and lowering the other two that defines the clinical markers of being ketogenic—the state in which you are actually using fat as a primary fuel source. There was also no change in bodyweight or reduction in food intake between the rats that consumed the ketones and the control group.
Ketones: Worth the Cost?
The human equivalent of the dose the rats consumed would be 39 grams of beta hydroxybutyrate acutely, or 77 grams per day over four weeks, for a 175-pound human. Given that ketone supplements cost well upward of three dollars for just one 11 gram serving, that's no small expense. So you'd definitely want to be confident that it's money well spent. Unfortunately, the effects for humans have yet to be investigated.
I don't think this means you need to disregard ketones as total bunk, though. On the contrary, it may just require a change of perspective. Specifically, I recommend thinking of them not as an alternative to carbohydrates or protein, but rather as an alternative caloric fuel. My experience—one that I'll admit hasn't yet been investigated directly using humans—is that short-term ketone supplementation can help reduce hunger and support cognitive energy during periods of caloric restriction.
Admittedly, though, whether they actually prove to do so under well-controlled and rigorously designed study conditions remains to be seen.
The bottom line, for now: Ketone supplements, such as beta hydroxybutyrate (BHB) salts or esters, don't appear to stimulate the body's liberation and burning of stored body fat as fuel on their own. And no, raising blood levels of ketones by consuming a ketone supplement isn't the same thing as your cells manufacturing ketones to support energy needs.
However, that isn't to say ketone supplements may not be useful in helping you to combat the downsides that accompany intense dieting.
- de Oliveira Caminhotto, R., Komino, A. C. M., de Fatima Silva, F., Andreotti, S., Sertié, R. A. L., Reis, G. B., & Lima, F. B. (2017). Oral β-hydroxybutyrate increases ketonemia, decreases visceral adipocyte volume and improves serum lipid profile in Wistar rats. Nutrition & Metabolism, 14(1), 31.