9. Bad breath

Although low carb dieting might improve your physique and even athletic ability, it's not going to do anything for your breath. Burning fat instead of carbohydrate produces ketones. In everyday diets ketones provide your brain with energy, but when there is an excess of fat burning going on (and therefore an excess of ketones being produced) the body excretes the extra ketones through breath and urea, often giving you a rather unpleasant smell.

This isn't easy to counteract. As keto breath is nothing to do with the health or cleanliness of your teeth or mouth, no amount of brushing, flossing and mouthwash swilling will make it go away. You can mask it with mints or fresheners, but the only real solution is to up your carbohydrate intake.