If you're worried about making a life insurance application because of your weight, you're certainly not alone. According to a 2007 report by the Trust for America's Health, adult obesity rates exceed 25 percent of the population in 19 states. Worst off is Mississippi, which breaks the 30 percent mark for adult obesity.

If you're obese, and especially if you have additional medical conditions such as diabetes or high blood pressure, you could be entering choppy insurance waters.

If you're about 10 pounds over your "ideal" weight, your life insurance application won't be affected. But if you're obese, and especially if you have additional medical conditions such as diabetes or high blood pressure, you could be entering choppy insurance waters.

How do you know if you're officially overweight or obese? It's judged by how much body fat you're carrying, which is calculated using your height and weight to determine your Body Mass Index (BMI). According to the Centers for Disease Control and Prevention (CDC), you are an overweight adult if your BMI is between 25 and 29.9. You are obese if your BMI is 30 or higher.

The CDC has an online BMI calculator that makes it easy to find out your number.

Obesity does not exist in a vacuum; it can lead to other serious health conditions, which is why it affects your life insurance rates. According to the CDC, being overweight or obese increases your risk of the following conditions:

• Hypertension (high blood pressure)
• Osteoarthritis (a degeneration of cartilage and its underlying bone within a joint)
• Dyslipidemia (such as high cholesterol)
• Type 2 diabetes
• Coronary heart disease
• Stroke
• Gallbladder disease
• Sleep apnea and respiratory problems
• Some cancers (such as endometrial, breast and colon)

Life insurers weigh in

Life insurers all have their own underwriting guidelines, but generally speaking, you can get the best preferred rates (often called "Preferred Plus") even if your BMI is up to 26 to 28. A higher BMI will likely push you down into the next rate class, called "Preferred," which can cost roughly 15 to 35 percent more in premiums than the Preferred Plus class. Once you're past a BMI of 30, you're likely out of the Preferred class.

Many life insurers have a rate class between Preferred and Standard, sometimes called Standard Plus, where you'll likely pay 30 to 40 percent more than the Preferred class as long as your BMI is around 32 or 33.

Is your BMI around 35 to 38? Now you're jumping into the Standard rate class with everyone else of unexceptional health. Here you'll pay about 15 to 25 percent more than Standard Plus rates.

These guidelines are not written in stone and there are numerous exceptions and variations among life insurers. That's why it's crucial to shop around for the best rates; comparison shopping can save you thousands of dollars by the end of your policy. If you are in a rate class that you find unaffordable, you could also consider lowering your death benefit amount in order to decrease your total premium bill. In addition, according to life insurance experts, senior citizens (age 65 or 70 and up) are often held to less strict weight standards, with looser build limits applied to them.

Not even the skinny are immune to weight-related underwriting. Many life insurers have weight minimums, too, and charge more when someone is deemed too skinny.