John Chapman and Leon Bustin, better known as Lean Machines are British nutritionists and personal trainers who have run a joint channel since 2011.
Their channel aims to help with health, fitness and motivation. They also teach about nutrition and diet. Their book, The Lean Machines: Eat Well, Move Better and Feel Awesome was released in 2016. Jamie Oliver and Tom Daley have guest starred on their channel. They currently have over 300,000 subscribers.