Dr. Steven Gundry, a cardiologist, heart surgeon, medical researcher and author, is perhaps best known for his "Plant Paradox" book, which was a massive bestseller. He has since published another book called "The Energy Paradox: What to Do When Your Get-Up-and-Go Has Got Up and Gone."

As the name implies, this book delves into the origins of fatigue and how to improve your energy at the molecular level. While he had not planned on writing a book about energy optimization, upward of 60% of his patients suffer from fatigue and a feeling of general malaise, so, clearly, this is something that affects an enormous number of people.