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Symptoms » Obesity » Diagnostic Tests
 

Diagnostic Tests for Obesity

Diagnostic Test list for Obesity:

The list of diagnostic tests mentioned in various sources as used in the diagnosis of Obesity includes:

  • Physical examination
    • Calculate the Body mass index (BMI) = weight (kg) / height (m2)
    • Obesity is defined as a BMI of 30-40. Morbid obesity is defined as a BMI of over 40
    • Calculate Waist-Hip ratio. Obese people with a high waist-hip ratio (over 1.0 in men and over 0.9 in women) have a significantly greater risk of diabetes mellitus, stroke, heart attacks and early death than equally obese people with lower waist-hip ratio
    • Determine the distribution of body fat. If the obesity is predominantly abdominal, especially with a moon-shaped face, must consider Cushing's syndrome. Type 2 diabetes is also associated with abdominal obesity. If the obesity is predominantly of the lower legs, must consider lipodystrophy
    • Measure Blood pressure. Obesity will increase blood pressure directly. Cushing's syndrome is associated with high blood pressure
    • Examine for signs of Cushing's syndrome - e.g. thin skin, bruising, high blood pressure, stretch marks, proximal muscle weakness, acne, pigmentation, excess hair on face, frontal balding in males, moon face, buffalo hump, truncal obesity, fluid retention.
    • Examine for signs of hypothyroidism - e.g. slow heart rate, slowedreflexes, coarse dry brittle hair, dry cool skin, goiter.
    • Examine for signs of Acromegaly such as excessive size of hands, feet, nose, lips, face, jaw and tongue
    • Examine for signs of atherosclerosis (hardening of the arteries) including reduced or absent peripheral pulses, enlarged heart and bruits heard in the carotid arteries in the neck. Obesity is a major risk factor for atherosclerosis which in turn increases the risk of heart attacks, strokes, kidney failure and peripheral vascular disease
  • Blood tests
    • Full blood count
    • Electrolytes - looking for low potassium in Cushing's syndrome due to adrenal tumors.
    • Renal function tests
    • Liver function tests
    • Thyroid function test
    • Fasting blood sugar level. Diagnosis of Diabetes mellitus requires fasting blood sugar level to be greater or equal to 7.0 mmol/L
    • Fasting blood lipids, including total cholesterol, LDL, HDL, triglycerides
    • 24-36 hour fasting blood sugar and insulin levels, if suspect insulinoma
    • 5 hour glucose tolerance test, if suspect insulinoma
    • Serum cortisol level, if suspect Cushing's syndrome
    • Cortisol suppression test, if suspect Cushing's syndrome
    • Testosterone
    • Chromosomal analysis will help diagnose Klinefelter's syndrome (in males), Turner's syndrome (in females) and Prader-Willi syndrome in children
  • Urine tests
    • Urine analysis to test for sugar
    • 24 hour free cortisol, if suspect Cushing's syndrome
  • Radiological investigations
    • Chest X-Ray may detect signs of heart disease due to obesity
    • Adrenal gland CT scan may detect adrenal tumors that may cause 15% of cases of Cushing's syndrome
    • Pituitary gland CT scan or MRI - may detect pituitary tumor that may cause 60% of cases of Cushing's syndrome.
    • Chest X-Ray and/or CT scan may detect a lung cancer that rarely may produce ACTH hormone that can cause Cushing's syndrome
    • Pelvic ultrasound scan will help diagnose polycystic ovaries
  • Electroencehalogram (ECG) - to screen for heart disease due to obesity.
  • Body Mass Index (BMI) - BMC 25..<30 is overweight; BMI >= 30 is obesity.
  • Weight-for-height charts
  • Skinfold thickness measurement
  • Bioelectrical impedance analysis (BIA)

Home Diagnostic Testing

These home medical tests may be relevant to Obesity causes:

Tests and diagnosis discussion for Obesity:

Everyone needs a certain amount of body fat for stored energy, heat insulation, shock absorption, and other functions. As a rule, women have more body fat than men. Most health care providers agree that men with more than 25 percent body fat and women with more than 30 percent body fat are obese.

Measuring the exact amount of a person's body fat is not easy. The most accurate measures are to weigh a person underwater or to use an X-ray test called Dual Energy X-ray Absorptiometry (DEXA). These methods are not practical for the average person, and are done only in research centers with special equipment.

There are simpler methods to estimate body fat. One is to measure the thickness of the layer of fat just under the skin in several parts of the body. Another involves sending a harmless amount of electricity through a person's body. Both methods are used at health clubs and commercial weight loss programs. Results from these methods, however, can be inaccurate if done by an inexperienced person or on someone with severe obesity.

Because measuring a person's body fat is difficult, health care providers often rely on other means to diagnose obesity. Weight-for-height tables, which have been used for decades, usually have a range of acceptable weights for a person of a given height. One problem with these tables is that there are many versions, all with different weight ranges. Another problem is that they do not distinguish between excess fat and muscle. A very muscular person may appear obese, according to the tables, when he or she is not.

In recent years, body mass index (BMI) has become the medical standard used to measure overweight and obesity. (Source: excerpt from Understanding Adult Obesity: NIDDK)

Although the BMI ranges shown in the table are not exact ranges of healthy and unhealthy weight, they are useful guidelines. A BMI of 25 to 29.9 indicates a person is overweight. A person with a BMI of 30 or higher is considered obese. (Source: excerpt from Understanding Adult Obesity: NIDDK)

Body mass index (BMI) is a measure of body weight relative to height. You can use BMI to see whether you are underweight, normal weight, overweight, or obese. Use the body mass index table below to find your BMI.

  • Find your height in the left-hand column.
  • Move across in the same row to the number closest to your weight.
  • The number at the top of that column is your BMI. Check the word above your BMI to see whether you are normal weight, overweight, or obese.

Body Mass Index Table

For a printer-friendly version of this table, use the pdf.*
  Normal Overweight Obese
BMI 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
Height
(inches)
Body Weight (pounds)
58 91 96 100 105 110 115 119 124 129 134 138 143 148 153 158 162 167 172
59 94 99 104 109 114 119 124 128 133 138 143 148 153 158 163 168 173 178
60 97 102 107 112 118 123 128 133 138 143 148 153 158 163 168 174 179 184
61 100 106 111 116 122 127 132 137 143 148 153 158 164 169 174 180 185 190
62 104 109 115 120 126 131 136 142 147 153 158 164 169 175 180 186 191 196
63 107 113 118 124 130 135 141 146 152 158 163 169 175 180 186 191 197 203
64 110 116 122 128 134 140 145 151 157 163 169 174 180 186 192 197 204 209
65 114 120 126 132 138 144 150 156 162 168 174 180 186 192 198 204 210 216
66 118 124 130 136 142 148 155 161 167 173 179 186 192 198 204 210 216 223
67 121 127 134 140 146 153 159 166 172 178 185 191 198 204 211 217 223 230
68 125 131 138 144 151 158 164 171 177 184 190 197 203 210 216 223 230 236
69 128 135 142 149 155 162 169 176 182 189 196 203 209 216 223 230 236 243
70 132 139 146 153 160 167 174 181 188 195 202 209 216 222 229 236 243 250
71 136 143 150 157 165 172 179 186 193 200 208 215 222 229 236 243 250 257
72 140 147 154 162 169 177 184 191 199 206 213 221 228 235 242 250 258 265
73 144 151 159 166 174 182 189 197 204 212 219 227 235 242 250 257 265 272
74 148 155 163 171 179 186 194 202 210 218 225 233 241 249 256 264 272 280
75 152 160 168 176 184 192 200 208 216 224 232 240 248 256 264 272 279 287
76 156 164 172 180 189 197 205 213 221 230 238 246 254 263 271 279 287 295

  Obese Extreme Obesity
BMI 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54
Height
(inches)
Body Weight (pounds)
58 177 181 186 191 196 201 205 210 215 220 224 229 234 239 244 248 253 258
59 183 188 193 198 203 208 212 217 222 227 232 237 242 247 252 257 262 267
60 189 194 199 204 209 215 220 225 230 235 240 245 250 255 261 266 271 276
61 195 201 206 211 217 222 227 232 238 243 248 254 259 264 269 275 280 285
62 202 207 213 218 224 229 235 240 246 251 256 262 267 273 278 284 289 295
63 208 214 220 225 231 237 242 248 254 259 265 270 278 282 287 293 299 304
64 215 221 227 232 238 244 250 256 262 267 273 279 285 291 296 302 308 314
65 222 228 234 240 246 252 258 264 270 276 282 288 294 300 306 312 318 324
66 229 235 241 247 253 260 266 272 278 284 291 297 303 309 315 322 328 334
67 236 242 249 255 261 268 274 280 287 293 299 306 312 319 325 331 338 344
68 243 249 256 262 269 276 282 289 295 302 308 315 322 328 335 341 348 354
69 250 257 263 270 277 284 291 297 304 311 318 324 331 338 345 351 358 365
70 257 264 271 278 285 292 299 306 313 320 327 334 341 348 355 362 369 376
71 265 272 279 286 293 301 308 315 322 329 338 343 351 358 365 372 379 386
72 272 279 287 294 302 309 316 324 331 338 346 353 361 368 375 383 390 397
73 280 288 295 302 310 318 325 333 340 348 355 363 371 378 386 393 401 408
74 287 295 303 311 319 326 334 342 350 358 365 373 381 389 396 404 412 420
75 295 303 311 319 327 335 343 351 359 367 375 383 391 399 407 415 423 431
76 304 312 320 328 336 344 353 361 369 377 385 394 402 410 418 426 435 443

Source: Adapted from Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults: The Evidence Report. (Source: excerpt from Am I at Risk for Type 2 Diabetes: NIDDK)

A number of methods are used to determine if an individual is overweight or obese. Some of them are based on mathematical calculations of the relation between height and weight--others are based on measurements of body fat. These methods are described below.

Body Mass Index

Body Mass Index (BMI) can be used to measure both overweight and obesity in adults. It is the measurement of choice for many obesity researchers and other health professionals. BMI is a direct calculation based on height and weight, and it is not gender-specific. Most health organizations and published information on overweight and its associated risk factors use BMI to measure and define overweight and obesity. BMI does not directly measure percent of body fat, but it provides a more accurate measure of overweight and obesity than relying on weight alone.

BMI is found by dividing a person's weight in kilograms by height in meters squared. The mathematical formula is:

weight (kg)/height squared (m2).

To determine BMI using pounds and inches, multiply your weight in pounds by 704.5,* then divide the result by your height in inches, and divide that result by your height in inches a second time (Source: excerpt from NIDDK _ Statistics Related to Overweight and Obesity: NIDDK)

The National Institutes of Health (NIH) identify overweight as a BMI of 25-29.9 kg/m2, and obesity as a BMI of 30 kg/m2 or greater. However, overweight and obesity are not mutually exclusive, since obese persons are also overweight.1 Defining overweight as a BMI of 25 or greater is consistent with the recommendations of the World Health Organization 2 and most other countries. (Source: excerpt from NIDDK _ Statistics Related to Overweight and Obesity: NIDDK)

Weight-for-height charts are another measure used to determine if a person is overweight (although they do not measure body fat). These charts, which have been used by doctors and other health care workers for decades, usually give a range of acceptable weights for a person of a given height. Many versions of weight-for-height charts exist, some showing different acceptable weight ranges for men and women. Health care workers often disagree over which is the best chart to use. The 2000 Dietary Guidelines for Americans, published jointly by the U.S. Departments of Agriculture and Health and Human Services, provide the most up-to-date weight-for-height chart. The healthy weight range in this chart corresponds to a BMI between 18.5 and 25. (Source: excerpt from NIDDK _ Statistics Related to Overweight and Obesity: NIDDK)

Measurements of Body Fat

There are a number of ways to measure body fat. Historically, the standard method is to weigh a person underwater; this procedure is limited to laboratories with specialized equipment.

Other simpler methods for measuring body fat include skinfold thickness measurements and bioelectrical impedance analysis (BIA). Skinfold thicknesses are measures of the subcutaneous (lying just beneath the skin) fat at specific sites of a person's body, such as the triceps (the back of the upper arm). Accurate measurements of skinfold thickness depend on the skill of the examiner and may vary widely when measured by different examiners.

To measure body fat using BIA, a harmless amount of an electrical current is sent through the body. The body's ability to conduct an electrical current reflects the total amount of water in the body. Generally, a higher percent body water indicates a larger amount of muscle and lean tissue. Mathematical equations are used to translate the percent body water measure into an indirect estimate of body fat and lean body mass. A standard method should be used to measure bioelectrical impedance because dehydration, recent exercise, skin and room temperature, and placement of electrodes all can affect test results. To obtain the most precise reading, the person being tested should fast for at least 4 hours and lie down for at least several minutes prior to testing. BIA may not be accurate in severely obese individuals, and it is not useful for tracking short-term changes in body fat brought about by diet or exercise.

In addition to body weight and height measurements, health professionals may also rely on a person's waist measurement to determine the location of excess body fat and the corresponding health risks. Analogous to BMI, health risks increase as waist circumference increases. A woman whose waist measures more than 35 inches and a man whose waist measures more than 40 inches may be at particular risk for developing health problems. Studies indicate that increased abdominal or upper body fat is related to the risk of developing heart disease, diabetes, high blood pressure, gallbladder disease, stroke, and certain cancers, and is associated with overall mortality (likelihood of death). Body fat concentrated in the lower body (around the hips, for example) may be less harmful in terms of mortality and morbidity (likelihood of disease), with the exception of varicose veins and orthopedic problems (Source: excerpt from NIDDK _ Statistics Related to Overweight and Obesity: NIDDK)

The definitions or measurement characteristics for overweight and obesity have varied over time, from study to study, and from one part of the world to another. The varied definitions affect the prevalence statistics of studies and make it difficult to compare data from different studies and from different countries. (Source: excerpt from NIDDK _ Statistics Related to Overweight and Obesity: NIDDK)

The words obesity and overweight are generally used interchangeably. However, according to the Institute of Medicine report, their technical meanings are not identical. Overweight refers to an excess of body weight that includes all tissues, such as fat, bone and muscle. Obesity refers specifically to an excess of body fat. It is possible to be overweight without being obese, as in the case of a body builder who has a substantial amount of muscle mass. It is possible to be obese without being overweight, as in the case of a very sedentary person who is within the desirable weight range but who nevertheless has an excess of body fat. However, most overweight people are also obese and vice versa. Men with more than 25 percent and women with more than 30 percent body fat are considered obese. The USFDA has released a chart detailing recommended weights relative to height; women should be in the lower end of their appropriate weight range, according to the chart. (Source: excerpt from Diet: NWHIC)

Conditions listing medical symptoms: Obesity:

The following list of conditions have 'Obesity' or similar listed as a symptom in our database. This computer-generated list may be inaccurate or incomplete. Always seek prompt professional medical advice about the cause of any symptom.

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Conditions listing medical complications: Obesity:

The following list of medical conditions have 'Obesity' or similar listed as a medical complication in our database.

 

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