It's not news to you that healthy eating is good for your heart. But with all of the different diets and conflicting information out there about what to eat, how do you choose a smart eating strategy? Recent research has confirmed the fact that cutting back on calories does matter—it's not just what you eat, but how much. Here's advice on how to limit what you consume without going hungry. Follow these expert tips and you will not only weigh less over time but also lower your risk of the leading cause of death nationwide: heart disease.

Get a handle on it. You may think you know what you're eating, but you won't know for sure until you write it down. "Most people greatly underestimate how much they are eating," says Larry Tucker, PhD, professor of exercise sciences at Brigham Young University and author of a study on the benefits of restrained eating. "We frequently hear people say ‘I hardly eat anything but I'm gaining weight.' That's an impossibility."

No time to scribble what you nibble? Use an online tool to record everything you eat and drink, plus serving sizes, for a few days. Then check the federal food guide pyramid to see how your current diet stacks up to recommendations. "What usually happens is folks fall short in fruits and vegetables, dairy, and whole grains," says Jeannie Gazzaniga Moloo, PhD, RD, spokesperson for the American Dietetic Association.

Eat more. That's right—but only increase the amount of filling, yet low-calorie, items in your fridge. Those include nonstarchy vegetables, fruits, and whole grains. "We can eat more of them and take in fewer calories," says Tucker. So reach for the broccoli and bell peppers instead of a bagel. "When we do that we can eat to the point of satisfaction and still consume relatively few calories," he notes. These foods also reduce your risk of heart disease.

How to get those five to nine servings of produce every day? "Make a deal with yourself that at each meal or snack you're going to bring in a serving of fruits or vegetables," suggests Gazzaniga Moloo. She also recommends you get at least half of your grain requirement from whole grains such as oatmeal and brown rice. Extra tip: A whole-grain item should have half the number of sugar grams as protein and fiber grams combined.

Trim by a third. To control portions, start paying attention to serving sizes on food packaging. One serving is often less than you might think. "A serving size of cheese is an ounce and a half—that's about the size of your thumb. A serving size of meat is a deck of cards," says Gazzaniga Moloo.

Another tactic: Fill your plate as you normally would, then take off one third, Tucker suggests. This amount allows you to cut back without feeling deprived.

Drink up. "Often people are eating because they are thirsty," notes Gazzaniga Moloo. "Fluids can also help fill us up." So sip water, with a lemon or lime wedge, all day long. Opt for lower calorie beverages, like unsweetened iced tea, over soda and venti lattes.

Try, try again. If you slip up and find yourself wolfing down a slice of pepperoni pizza or a fried chicken breast, forgive yourself. Then go right back to your eating plan of writing down what you eat, consuming a fruit or vegetable at every meal, drinking plenty of water, and eyeing portion sizes. The payoff will be a slimmer, trimmer you with a stronger heart.