context: Many Americans struggle to control their weight. The country's obesity problem is well known: 1 in 3 of us is obese, and the rate is rising. But you still might wonder what a healthy weight is, and how to get there (and stay there) the right way. It's pretty easy to figure out the estimated healthy weight. You can use two simple tools. The first is called body mass index ( BMI). To figure out your BMI, just use this math formula: Multiply your weight in pounds by 703 and divide it by your height (in inches) squared. So, for example, if you weigh 185 pounds and are 5-foot-5 (65 inches), then your BMI works out this way: 185 x 703 = 130,055 65 x 65 = 4,225 130,005 Ã· 4,225 = 30.78 (round up to 30.8) Obesity in adults is defined as having a BMI of 30.0 or above. The other ranges are: Overweight = 25.0 to 29.9 Normal weight = 18.5 to 24.9 Underweight = under 18.5 BMI is a common tool to give you some idea of where you are. But it doesn't measure body fat. It's not meant to give a diagnosis or tell you for sure that you have a weight problem. For example of how it can be off, muscular people might have a high BMI without being obese. And BMI can underestimate fat in older people and others who have lost muscle. If you think you are obese or have questions about healthy weight, talk to your doctor. There's a second way to get an idea of how close you are to a healthy weight -- just measure your waist. The waist is key because tummy fat can be more serious and put you at a greater risk of things like type 2 diabetes, high blood pressure and heart disease. Like BMI, measuring your waist doesn't show for sure that you're overweight. They are both common, general screening tools. But in general, here are the guidelines for men and women: A man's waist should be no more than 40 inches If you're a woman who isn't pregnant, it should be no more than 35 inches. Here's how to measure your waist: Stand up and wrap a measuring tape around your waist (just above the hip bones). The tape should be snug but not pressed into your skin. Breathe out before you measure. Doctors have another tool based on the inches around your hips compared with the inches around your waist. To figure out your waist-to-hip ratio: Measure your waist at the thinnest part. Measure your hips at the widest part. Divide the waist by the hips. Men with a waist-to-hip ratio higher than 0.9 have too much of a belly (think apple-shaped). Women with a number higher than 0.85 are carrying too much weight (more like a pear). The waist-to-hip guidelines differ by sex because men tend to carry extra weight in their bellies, while women show it more in the hips and buttocks. Several things help determine a person's weight, including genes and hormones. But being obese usually comes from eating more calories than you use. Your body holds on to extra calories and turns them into fat. So there are two things you must change to lose weight in a healthy and lasting way: Eat right. Americans love fast food, sodas and processed foods. They add up. Move more. Our lifestyles can be short on exercise, playing, or just moving enough to burn the fuel we take in. Your doctor might also want to talk about: Other behavioral changes Medicines Weight-loss surgery If a diet sounds too good to be true, it probably is. The same goes for promises that you'll lose weight fast without changing your diet or exercise habits. A loss of 1 to 2 pounds a week is about right. So think âslow and steadyâ to keep the weight off for good. For your diet: Eat more fruits and vegetables. Get good protein and plenty of fiber. Limit salt, sugar, and fat. Be careful with your portions. Talk to your doctor about how many calories you should consume to lose weight. For women it's generally up to 1,500 calories a day; for men it's up to 1,800. You'll need to cut your calories by 500 to 1,000 calories a day to lose that 1-2 pounds per week. For movement: Aim for at least 2.5 hours of aerobic exercise (like brisk walking) every week. You'll likely need even more than that to lose weight. Do some muscle strengthening at least twice a week. Add ordinary movement to that, as well, to burn calories throughout the day. ( Park far from entrances. Take walks around the neighborhood. Get up from your desk and move regularly). Just the word âdietâ sounds like a drag, doesn't it? So don't think about dieting. Think about making better lifestyle choices. Healthy eating and exercise can connect you with family, friends, and others with similar goals. You can join a support group or fitness center, take a class, or play with your kids. Healthy living is a way of life, and the benefits are worth it.