Numbers That Matter as Much as Your Weight

Body mass index uses your height to gauge if your weight is healthy, but even that's not foolproof. Your body type, ethnic group, and muscle mass can change the meaning of the number. For example, if you start exercising regularly, you may gain weight as you build muscles. When you're trying to lose weight to be healthier, there are other numbers you should pay attention to, too, instead of focusing only on the scale.

Breathe out, and wrap a tape measure around yourself midway between your hip bone and ribs. No matter your height or build, if your waist measures more than 40 inches (35 inches for women who aren't pregnant), you probably have extra fat around your heart, liver, kidneys, and other organs. Besides needing a larger pants size, you're more likely to have heart disease, high blood pressure, diabetes, sleep apnea, and colorectal cancer.

Ideally, you want your upper, or "systolic," number to be below 120, and your lower "diastolic" number to be below 80. Once the numbers are 130 and 80, or higher, you have high blood pressure. You may not have any symptoms, yet it can damage your heart and blood vessels. Eventually, it can also cause problems with your kidneys, eyes, and sex life.

When you're healthy, it should be under 100 mg/dL before you eat and less than 140 mg/dL a couple of hours later. (Your doctor will set your targets, which may be a bit higher, when you have diabetes.) Higher glucose levels can lead to long-term damage of your heart, blood vessels, and kidneys. Daily exercise and healthy eating can help bring your blood sugar down.

This set of tests measures different kinds of fats in your blood: "bad" (LDL) cholesterol, "good" (HDL) cholesterol, and triglycerides. The general rule of thumb is that your total cholesterol score should be less than 200 mg/dL. You want your HDL to be 60 mg/dL or more and your triglycerides below 150 mg/dL. Unhealthy levels could lead to narrow or blocked arteries, heart attack, and stroke.

You should get at least 30 minutes a day, at least 5 days a week, of moderate exercise (heart is pumping, lungs are working) like walking or gardening. It's best to spread the activity out, over the week and even the day, as long as you're doing it for at least 10 minutes. Make sure that twice a week you're using all your major muscles to keep them strong. Muscles will burn more calories than fat, too, even at rest.

Even working out an hour a day, 7 days a week, won't undo the unhealthy effects of sitting all day. When you stay seated, your body metabolism slows, so you burn fewer calories. Your muscles and joints stiffen up, and your back may hurt. Get up every 30 minutes or so. Stretch or take a short walk. That's a good way to help you hold onto those hard-earned gains from the gym and possibly live longer.

To improve your health and your mood, 10,000 every day is the number you'll hear a lot. But there's nothing magical about it. Anywhere between 4,000 and 18,000 may be good for you. The types of steps you take are important, too. The point is to make sure you're getting enough moderate activity every day. Talk to your doctor about what number makes sense for you. A smartphone app or fitness tracker may help you meet your goal.

Adults usually need 7 to 9 hours a night. Our bodies use that time to fix tissue, make hormones, and grow muscle. Our brains use it to process the information and learning of the day into memories. Not enough sleep can make you hungrier -- and make junk food more appealing. Though it helps to get a bit of extra shut-eye if you haven't had enough, you can't really make up what you've missed in a night's sleep.

Limit yourself to 2 hours a day that's not work- or school-related. And yes, that includes your smartphone. Too much time glued to that device has led to a new condition called "text neck" that can cause back, neck, and shoulder pain. Screens in the bedroom can mess with your sleep. Screens during the day can make you less active and more distracted. There's even research being done on whether screen time causes brain damage.

Most people can stay hydrated by drinking water when they're thirsty. To set a baseline, drink at least one glass of water with and between each meal. You may need more if it's hot or dry outside, or when you're pregnant. Drink before you work out, every 10-20 minutes during exercise (depending on the weather and how much you sweat), and within 30 minutes afterward. A glass of water might do the trick instead when you want a snack.

Men and all adults 30 and under should shoot for 2 cups a day. Women over 30 should stick with 1 1/2 cups. What's a "cup"? A small apple, a large banana, a medium pear, 8 big strawberries, or 1/2 cup of dried fruit. If you're more active, you may be able to eat more since you're burning the extra calories. Fruits have lots of nutrients that many people don't get enough of, like vitamin C, potassium, fiber, and folic acid.

You need more veggies than fruit: 2-3 cups a day, depending on your age and sex. Mix it up throughout the week with dark green (broccoli, spinach, kale), red and orange (tomatoes, red peppers, carrots, sweet potatoes), and starchy veggies (corn, potatoes, green peas), as well as beans, peas, and other vegetables (cabbage, onions, zucchini, cauliflower, mushrooms). Fresh, frozen, canned, or dried -- raw or cooked -- it all counts.

Moderation is key: a drink a day for women, two for men. (A drink can be 5 ounces of wine, 12 ounces of beer, or 1.5 ounces of liquor.) More than that, and any potential benefits start to fade. And the calories add up. Alcohol can be bad for your liver, kidneys, and heart, and could hurt your baby if you're pregnant. More than four drinks a day or 14 in a week for men, three in a day or seven in a week for women, could signal a problem.

Literally, zero. They cause more deaths than HIV, illegal drug use, alcohol, car accidents, and gun incidents combined. Being a "light" or "social" smoker still isn't OK. Even if you smoke less than five cigarettes a day, you may have early signs of heart disease and other health problems. Ask your doctor about using nicotine gum to help control your appetite while you quit.