The brain uses mainly glucose (sugar) for fuel, but it can also use ketones and lactate. During low-calorie dieting, the body produces ketones to supply fuels to the brain. The liver produces ketones that come from fatty acids released during fat breakdown that occur due to low calorie intake. Ketogenic diets (i.e., low-calorie diets that result in ketone production) decrease appetite and increase the feeling of fullness, even during severe caloric restriction. Ketogenic diets also affect risk factors of coronary artery disease. A study led by Antonio Paoli, from the University of Padova in Italy, found that combining a ketogenic diet with omega-3 fatty acid supplements reduced inflammation and improved cardiovascular risk factors better than the ketogenic diet alone. The effects of this combination on cardiovascular disease and the incidence of heart attack are not known.
Source: Marine Drugs, 13: 996-1009, 2015