Many studies have linked eating breakfast to good health, including better memory and concentration, lower levels of “bad” LDL cholesterol, and lower chances of getting diabetes, heart disease, and being overweight.

It’s hard to know, though, if breakfast causes these healthy habits or if people who eat it have healthier lifestyles.

But this much is clear: Skipping the morning meal can throw off your body’s rhythm of fasting and eating. When you wake up, the blood sugar your body needs to make your muscles and brain work their best is usually low. Breakfast helps replenish it.

If your body doesn’t get that fuel from food, you may feel zapped of energy — and you’ll be more likely to overeat later in the day.

Breakfast and Your Weight

Can a morning meal be good for your waistline? Some studies say yes. Researchers have found that on average, people who eat breakfast are thinner than those who don’t. That could be because eating foods with protein and fiber in the morning keeps your appetite in check the rest of the day.

But it doesn’t guarantee you’ll fit into those skinny jeans. A recent study compared weight loss among people who ate breakfast with those with didn’t. The meal didn’t make any difference.

Why Kids Need Breakfast

Sometimes children don’t feel like eating in the morning, but it’s important that they do. Their growing bodies need the nutrients and fuel.

Kids who don’t eat in the a.m. have a harder time focusing, and they become more tired in school. They may also be cranky or restless. And it isn’t just their moods that can suffer. Their schoolwork can, too. One study showed that kids who ate breakfast had higher test scores than those who didn’t. Most children don’t get all the vitamins and minerals they need from just lunch and dinner.

A Doughnut Won’t Do

You don’t need to eat a big meal for breakfast, but it’s a good idea to have something small within an hour of waking up. Even last night’s leftovers zapped in the microwave will do.

Resist that pastry or doughnut, though. Your best bet is a mix of foods that have carbohydrates, protein, healthy fats, and fiber. Carbs will give you energy right away, and the protein will give it to you later on. Fiber keeps you feeling full.

Try a whole-grain cereal, low-fat milk and fruit, or a breakfast smoothie made from low-fat yogurt, fruit, and a teaspoon of bran. Nuts or whole-grain granola bars are also easy options.