Yeah, yeah--you've heard a million times that you must start your day with a balanced breakfast. This advice bears repeating, however.

An Imperial College London study found that when people skipped breakfast, the reward centers in their brains lit up when they were shown pictures of high-calorie foods. That means if you skip breakfast, you'll be more tempted by bad-for-you snacks later in the day.

What's more, a 2013 study found that women who enjoyed a large morning meal had a larger drop in ghrelin, the hunger hormone, than those who ate a small breakfast.