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- Ketone esters are designed to put the body in ketosis without doing the keto diet.
- They allow people to bypass keto flu and also still eat carbs.
- However, obesity specialist Dr. Spencer Nadolsky called them "a big marketing gimmick."
- Visit Insider's homepage for more stories.
Ketone esters are supplements that claim to put the body into ketosis, without requiring a person to follow the ketogenic diet.
When in ketosis, the body burns fat for fuel, and it's usually reached by following the high-fat, low-carb keto diet, or through fasting.
Ketones are made by the body when glucose and glycogen (from carbs) aren't available for energy.
Ketone esters were first developed for use by the US Army to improve performance and focus and to reduce inflammation.
Research on ketone esters is limited, but they may come with unpleasant side effects. A small 2012 study by the University of Oxford found participants experienced negative consequences after taking ketone esters, such as nausea or dizziness.
Ketone esters like HVMN and Juvenescence are "generally recognized as safe" by the FDA, but doctors told Insider they aren't convinced the drinks are necessary for good health or weight loss.
Ketone esters claim to put you in ketosis without 'keto flu'
In the early stages of following a keto diet, many people experience what's known as keto flu, with symptoms including fatigue, irritability, nausea, constipation, and dizziness.
Ketone esters, like ketone salts (another type of exogenous ketone), aim to put you in ketosis without suffering flu symptoms.
You can still consume carbs and be in ketosis when taking ketone esters, however some keto dieters also take the supplement alongside the diet to boost their ketone levels, according to biohacker Dave Asprey.
Commonly consumed as a daily drink, ketone esters are expensive: The first two brands to hit the market in 2018, according to Keto Source, KetoneAid costs $94.95 for three servings and HVMN costs $99 for the same.
People who've tried them also claim the drinks are hard to swallow, with GQ's Brennan Kilbane describing the taste as "like a mixture of vodka, tequila, vegetable oil, and battery acid."
Business Insider reporters Melia Robinson and Erin Brodwin tried HVMN and said: "It caused our eyes to tear. We gagged, loudly."
Ketone esters are unlikely to lead to weight loss
Ketone ester drinks aren't low-calorie, with new brand Juvenescence's keto ester drink, Metabolic Switch, clocking in at 210 calories. Adding the drink to your daily calorie count without cutting calories from other meals can hinder your weight loss goals.
However small-scale research suggests they could suppress appetite - Kilbane wrote in a piece for GQ that he drank HVMN's ketone ester in the morning found he wasn't hungry until the end of the workday.
Dr. Spencer Nadolsky, a physician specializing in weight management and obesity, told Insider that the drinks are "not useful" for most people.
"There are some potential therapeutic benefits to ketone ester drinks but losing weight isn't one of them," he said. "Even if blood ketone levels increase, what was the intent of that? Most people think ketosis or increased ketones means more fat loss."
Nadolsky believes ketone esters are "a big marketing gimmick."
"It's just an added source of calories without any data to show weight loss," he said. "But if using it for potentially the other therapeutic benefits being studied then maybe but would still do it under the supervision of a well trained physician."
UK National Health Service doctor Ravina Bhanot told Insider that ketosis can have health benefits, as long as it doesn't take the place of a balanced diet.
"Using the product every day for a long time can cause adverse effects such as high risk of heart disease, kidney stones, reduce muscle mass and confusion," she said.