Bulletproof coffee is a beverage containing coffee, unsalted grass-fed butter (high in omega-3 fatty acids) and medium-chain triglycerides (MCTs). Medium-chain triglycerides are fats that provide a lot of energy in a small volume, just like fat, yet are absorbed and metabolized rapidly, just like carbohydrates. Medium-chain triglycerides may reduce body fat, improve the metabolism of carbohydrates and proteins, enhance the absorption of essential elements such as calcium and potassium, and decrease the risk of heart disease by reducing blood cholesterol and triglycerides.
There are claims that the Bulletproof line of drinks curbs hunger, improves mental focus and speeds weight loss. These claims are doubtful. The brain uses mainly carbohydrates as fuels, so the high fat content of the drink would not help brain energetics. Animal studies show that high-fat diets decrease mental function and promote memory loss.
People use Bulletproof coffee as a meal replacement. A cup contains more than 300 calories, which would promote weight gain if people also ate normally. Also, MCTs trigger only minimal weight loss. Fads come and go, so it will be interesting to see if Bulletproof coffee is around one or two years from now. (Lipids in Health and Disease, 13: 194, 2014; The New York Times, December 14, 2014)