New ketone drink could not only help you lose weight but could also treat epilepsy, diabetes, Alzheimer's, say scientists.
It might also be an incredible energy booster. When a group of international rowing champions took it, one of them beat a world record.
It's been developed by Kieran Clarke, professor of physiological biochemistry at Oxford University and head of its Cardiac Metabolism Research Group, at the behest of the U.S. Army.
Equally amazing is that the drink doesn't involve a new drug but contains something our bodies produce all the time.
This key ingredient is ketones - the tiny, but powerful sources of energy our bodies make naturally when we start using up our fat stores for energy because there are no carbohydrates around.
We all have slightly raised ketone levels before breakfast because we haven't eaten for a while. And if you fast for a few days or go on an Atkins-type high-fat diet, your body will start pumping out ketones. They are nature's way of keeping you supplied with energy - especially your brain and muscles.
The clever trick Professor Clarke has pulled off is to have found a way to make ketones in the lab. This means that instead of having to follow difficult you can just add ketones to a normal diet in the form of the drink.
It's a radical new approach, which flies in the face of more than 30 years of advice that a low-fat diet with lots of carbohydrates is the best way to lose weight, treat diabetes and protect your heart.
It also raises questions about the demonising of diets like Atkins, which are blamed for causing constipation and kidney failure.
Ketones are the reason why high-fat diets such as Atkins seem to work so well. Without the energy from carbohydrates, your body starts releasing stored fat, which the liver turns into ketones for energy.
The pounds drop off faster than with a low-fat diet because you are actively burning up stored fat. But there are other benefits of these ketogenic diets, as they are called. Blood sugar levels come down because you are eating hardly any carbohydrates.
In the first trial Professor Clarke has run on humans with diabetes, completed within the past few months, the effects were also impressive. In the week-long study, eight people with diabetes had three ketone drinks a day as well as their normal diet.
As with the rats, their weight dropped, but so did their glucose levels, cholesterol and the amount of fat in the blood. The amount of exercise they did went up as they had more energy. However, the study was small and as yet unpublished.
The Drink has its roots in ketogenic diets, which are designed to raise ketone production. One medical area where a very high-fat ketogenic diet is used as standard treatment is in childhood epilepsy.
Professor Clarke had been working on ketones as a high energy source for more than a decade when she approached DARPA, who funded the research that allowed her to discover a way to make ketones in the lab.
"No one had done it before," the Daily Mail quoted her as saying.
"We called it DeltaG, which is the biochemical name for energy, but also has a military ring to it - Delta Force and all," she said.
She tried the new compound on rats and found it boosted physical and mental performance.
But that wasn't all. The rats became much healthier. They lost body fat, had lower levels of triglycerides (fatty acids) in their blood and lower blood sugar levels. There were no signs of harmful side-effects.
So how does a drink that adds ketones help you lose weight if you're not burning fat to produce those ketones in the first place?
It is because ketones make you less hungry - they damp down hunger centres in the brain. This means you eat less and so you have the same weight loss as on a high-fat diet.