7 myths about how to stay in shape that need to die

Beyonce

Get fit. Stay fit. Easy goals to set, but they're hard to achieve.

At least part of the reason for that is that the science on fitness and dieting has changed over time. People who read about fitness in the '70s heard different information than those who read about fitness in the '90s. And the scientific consensus in the '90s was based on less complete information than researchers have today.

But those old ideas stick around, and sometimes bad new ideas - only supported by one or two studies - get repeated in the media as fact.

Here's the truth about some widely-believed myths about how to be healthy.