This is a healthy lifestyle based on human evolutionary physiology, not a diet. The only "down side" is that initially breaking one's addiction to eating the way modern humans eat can be challenging. If you're worried about weak teeth (or bones) due to a lack of calcium, just eat plenty of the right leafy greens (broccoli, spinach, etc.). There are also a number of us that continue to consume dairy products. Or, take a calcium supplement.