Breakfast is quite literally the meal meant to “break the fast” from all the hours you spend sleeping, and skipping it is known to cause a slew of bad chain reactions throughout the body. And yet, 31 million Americans (28% of whom are men ages 18-34) don't eat a morning meal, according to a study conducted by NPD Group, a marketing research company.

One of the most common reasons people skip breakfast is because they're just not hungry in the morning, says Josh Axe, D.N.M., a board-certified doctor of natural medicine and nutrition specialist. If you can relate, Axe suggests trying to start small with a liquid shake or healthy smoothie, keeping your dinner smaller, and cutting back on alcohol or snacks right before bed.

"For a healthy breakfast, most people will do best eating a combination of protein and good fats first thing in the morning—like eggs and avocado, both of which keep you satisfied for longer and help prevent low blood sugar fluctuations," Axe says. Most experts, he adds, suggest eating between 300-500 calories for breakfast, ideally within an hour or two after waking up. Avoid the drive-through, though—homemade breakfasts tend to be healthier.

Research from the University of Illinois at Urbana-Champaign found meals eaten in restaurants are usually significantly higher in total calories and hydrogenated fats, but lower in percentage of calories from protein, complex carbohydrates, and fiber than those eaten at home.

"Watch the liquid calories, which include fruit juices or sweetened coffee drinks," Axe says. "These are usually packed with sugar but provide little to no fiber, protein, and complex carbs to keep you fueled. If you are going to include carbohydrates with your breakfast, make it a low-glycemic kind like berries, plain rolled oats, sprouted whole grain bread, or sweet potato hash browns." And for the most part, avoid muffins, bagels, scones, and some packaged granola bars. They may seem healthy, but they're more like dessert than breakfast.

Need more inspiration to make a habit of eating a morning meal? Just read through to find out exactly what happens in your body when you skip breakfast.

Your blood sugar drops

Research published in the Journal of Frontiers of Human Nueroscience shows that eating breakfast helps restore glycogen and stabilizes levels of insulin. If you don't replenish your glucose stores in the morning, it'll leave you feeling overly hungry, cranky, and fatigued. (Yes, being “hangry” is a real health problem.) "These low blood-sugar symptoms are the first thing you're likely to experience from fasting all-night long," Axe says.

Your metabolism slows

There’s evidence that an early meal can stoke your metabolism and encourage your body to burn more calories throughout the day, according to the International Journal of Obesity. When you fast for too long, your body goes into protection mode, and begins to store as many calories as possible (think bears preparing for hibernation). "As a negative double whammy, when your metabolism slows, it can turn to the glucose stored in your muscles as a backup fuel source, effectively wasting away your muscles," Axe adds.

Your stress hormones skyrocket

Breakfast has a positive effect on cortisol, one of the primary “stress hormones” produced by the adrenal glands, according to research from the University of Texas at Austin. Cortisol has many functions including helping the body use sugar (glucose) and fat for energy and managing stress. "Normally, cortisol levels are highest about 7 a.m., so this is when it’s important to eat something to bring them back down," Axe says. "If cortisol levels remain elevated, you're likely to feel anxious or jittery."

Your heart takes a hit

Regularly skipping breakfast can make you more susceptible to weight gain and increase your risk for heart disease, obesity, high blood pressure, high cholesterol and diabetes, according to press release from the American Heart Association. In fact, a 16-year long Harvard study of nearly 27,000 men aged 45-82 years old found that those who skipped breakfast every day were 27% more likely to experience a heart attack or die as the result of coronary heart disease.