Ahh, the humble egg. Few foods out there are as versatile as this inexpensive protein source. These little orbs are filled with nutrients, including lutein and zeaxanthin (essential for healthy eyes!) and omega-3 fatty acids (an important part of keeping hearts healthy). And while the cholesterol content of egg yolks has caused some controversy, eating as many as four egg yolks per week shouldn't be a problem for most egg-lovers out there. With just 70 calories and 6 grams of protein per egg, incorporating eggs into any meal is an easy way to stay full for hours while also staying healthy.