Are you overweight?

Health care providers use body mass index (BMI), an approximate measure of body fat based on a person's height and weight, to determine whether a person's weight falls within a healthy range (see below). Another simple measurement is waist circumference. There are also several methods of estimating the percentage of your weight that is fat, including skin-fold measurement, bioelectric impedance, and underwater weighing.

What's your BMI?

To calculate your BMI, follow these four steps:

Measure your height in inches (without shoes) and your weight in pounds (without clothing).

Multiply your weight by 703.

Divide that number by your height.

Divide again by your height.

You can also use a Web-based calculator at

If your BMI is lower than 18, you are considered underweight. Underweight people also have higher death rates than people of normal weight do, but many people in this category are underweight because they already have a severe illness, such as cancer, chronic infections, or anorexia.

Table 1: What's your body mass index?
The body mass index (BMI) is an index of weight by height. The definitions of normal, overweight, and obese were established after researchers examined the BMIs of millions of people and correlated them with rates of illness and death. These studies found that the BMI range associated with the lowest rate of illness and death is 19–25.
Height	Weight in pounds
4'10"	91	96	100	105	110	115	119	124	129	134	138	143	167	191
4'11"	94	99	104	109	114	119	124	128	133	138	143	148	173	198
5'0"	97	102	107	112	118	123	128	133	138	143	148	153	179	204
5'1"	100	106	111	116	122	127	132	137	143	148	153	158	185	211
5'2"	104	109	115	120	126	131	136	142	147	153	158	164	191	218
5'3"	107	113	118	124	130	135	141	146	152	158	163	169	197	225
5'4"	110	116	122	128	134	140	145	151	157	163	169	174	204	232
5'5"	114	120	126	132	138	144	150	156	162	168	174	180	210	240
5'6"	118	124	130	136	142	148	155	161	167	173	179	186	216	247
5'7"	121	127	134	140	146	153	159	166	172	178	185	191	223	255
5'8"	125	131	138	144	151	158	164	171	177	184	190	197	230	262
5'9"	128	135	142	149	155	162	169	176	182	189	196	203	236	270
5'10"	132	139	146	153	160	167	174	181	188	195	202	209	243	278
5'11"	136	143	150	157	165	172	179	186	193	200	208	215	250	286
6'0"	140	147	154	162	169	177	184	191	199	206	213	221	258	294
6'1"	144	151	159	166	174	182	189	197	204	212	219	227	265	302
6'2"	148	155	163	171	179	186	194	202	210	218	225	233	272	311
6'3"	152	160	168	176	184	192	200	208	216	224	232	240	279	319
6'4"	156	164	172	180	189	197	205	213	221	230	238	246	287	328
BMI	19	20	21	22	23	24	25	26	27	28	29	30	35	40
	NORMAL						OVERWEIGHT					OBESE

What's your body shape?

Your body shape depends largely on where you tend to carry your weight, usually centered on either your waist or your hips and thighs. If you carry fat mainly around the middle of your body (known as "apple-shaped"), you're more likely to develop diabetes and related health problems than if you tend to be heavier around your hips and thighs ("pear-shaped"; see Figure 1). To measure your waist circumference, place a cloth tape measure around your bare abdomen just above your hipbones. Make sure the tape is snug and parallel to the floor. A waist circumference of more than 35 inches for women and more than 40 inches for men indicates a higher than normal risk. (See "Do you have metabolic syndrome?")

What's your body fat percentage?

You can estimate your body fat percentage by several different methods, but be aware that these tools aren't always accurate and doctors don't consider them useful to guide treatment. In general, these methods tend to be less accurate in people with obesity than in people who are slightly overweight or at a normal weight. But some athletes and people who are trying to tone their bodies while losing weight may find it motivates them to keep tabs on their body fat percentage. Healthy adult men have body fat percentages between 10% and 25%, whereas the range for women is between 18% and 32%. Higher percentages are considered abnormal and consistent with obesity. In children, body fat percentages above 25% in boys and 30% in girls are associated with being overweight.

Skin-fold thickness. A technician or health professional uses calipers, a measuring instrument, to gauge the thickness of a fold of skin on the body at several different sites, such as the upper arms, waist, and thighs. The measurements are entered into a formula to produce an estimate of body fat percentage. This method gives a reasonable estimate, but results often vary when different people take the measurements, making this test not very reliable.

Bioelectric impedance. This test uses a small, harmless electrical current to measure the electrical resistance of the body, based on the principle that lean body mass conducts electricity faster than fat body mass. Special "body fat" scales that use this principle in combination with your height and weight can calculate your body fat percentage. Results can vary with the amount of water in your body and are considered unreliable in people with obesity.

Underwater weighing. This test, based on the principle that fat tissue is less dense than muscle and bone, uses a special bathtub-sized tank to weigh a person underwater. That weight is then compared to the person's weight on land; a formula identifies the percentage of body fat that would account for the difference. Underwater weighing is considered the most accurate method, but it is generally available only at universities and research facilities.

Review Date: 2006-09-01

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