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KirsiPietiläinen

Assessment of an Obese Patient

Essentials

  • The overall assessment of an obese patient includes
    • measurement of weight and height and calculation of body mass index (BMI)
    • measurement of waist circumference (indicated if BMI is 25-35)
    • assessment of associated diseases
    • mapping of living habits and life situation.
  1. Determine the degree of obesity.
    • In adults the body mass index (BMI) is a suitable measure (see table T1).
    • Treatment is usually indicated if the BMI exceeds 30. The more overweight the person is, the more active measures are necessary.
  2. Assess the degree of abdominal obesity.
    • The assessment is based on measuring waist circumference.
    • Waist circumference measurement has the greatest impact on treatment in patients with BMI in the range 25-35. Weight reduction should be considered if the patient has abdominal obesity.
  3. Assess disorders associated with obesity.
    • Treatment should be particularly active if the patient has a disease that is related to obesity and that can be alleviated by weight reduction.
  • It is worthwhile to treat overweight (mild obesity, BMI 25-30) if the patient has an increased waist circumference (> 90 cm in women and > 100 cm in men) or if he/she has associated diseases or is at a great risk of such a disease.
  • Consider the patient's age when planning the treatment.
    • The younger the patient the more active the treatment should be.
    • The importance of maintaining exercise and preserving muscle mass is emphasized by age, particularly after retirement.
    • Intense weight reduction should be avoided in patients above the age of 65-70.

Body mass index and waist circumference Obesity and Waist-to-Hip-Ratio and Risk of Myocardial Infarction

  • Weight (kg) divided by square of height (m2 )
    • For example, 78 kg/(1.70 m × 1.70 m) = 27.0 kg/m2
  • See table T1. For calculation see program Bmi.
  • Waist circumference is measured with the patient standing. The correct place of measurement is the area between the iliac crest and the lowest rib, which is easily identified also in fairly obese patients (picture 1). The measurement becomes more accurate if the right level is marked on both sides by a pen and the measure passes over these marks. In women waist circumference > 90 cm and in men > 100 cm increases considerably the risk of cardiovascular disease. Even if the waist circumference is somewhat less (> 90 cm in men, > 80 cm in women), the risk is already slightly increased.
  • When BMI is > 30 the waist circumference is increased in most cases, and when BMI is > 35, the circumference is always increased.

Classification of weight based on the body mass index

IndexClass160 cm170 cm180 cm
<18.5underweight<47<53<60 kg
18.5-25normal range47-6453-7260-81 kg
25-30overweight64-7772-8781-97 kg
30-35obesity77-9087-10197-113 kg
35-40severe obesity90-102101-116113-130 kg
>40morbid obesity>102>116>130 kg
According to the WHO classification BMI 25-29.9 is "overweight" and BMI 30 or more is "obesity". In some classifications BMI 40 or more is named "morbid obesity". From clinical point of view this may be too rough, for which reason here the obesity classes are defined for every 5 BMI-units.
Investigating an obese patient
  • Aetiology
    • The most common cause is excessive energy intake in relation to consumption. Although the equation is physiologically clear, there are often several factors acting in the background (e.g. psychological or related to life situation); these should be clarified in a good spirit during an appointment. Individual variation is great.
    • Metabolic diseases are rare as a cause of obesity.
  • Associated diseases
    • Must be identified because they influence the treatment approach.
    • The most important associated diseases include
      • Diabetes or prediabetes (impaired fasting glucose, IFG, in which the fasting plasma glucose is 6.1-6.9 mmol/l, or impaired glucose tolerance, IGT, in which the plasma glucose 2-hour level in the glucose tolerance test is 7.8-11.0 mmol/l, or HbA1c is 39-46 mmol/l [5.7-6.4%]).
      • Fatty liver
      • Hypertension
      • Sleep apnoea Sleep Apnoea in the Adult
      • Lipid disorders (increased concentration of triglycerides and low concentration of HDL cholesterol)
      • Metabolic syndrome Metabolic Syndrome
      • Menstruation disorders and/or infertility
      • Osteoarthrosis of the knees
      • Urinary incontinence
      • Sleep apnoea syndrome
      • Asthma
  • Psychosocial factors
    • Many psychosocial problems in obese persons are caused by obesity and not vice versa.
    • Obese persons have many problems with self-esteem, and they have sometimes faced maltreatment also in the health care services. Therefore, discretion is an important starting point for discussing obesity. One can, for example, ask whether the obesity affects the patient's mood.
    • In a stressful life situation (economical problems, divorce etc.) weight reduction is easily postponed.
    • Treatment of depression is often warranted before treating the obesity.
    • Binge eating disorder (BED) is common in obese persons (uncontrolled episodes of binge eating weekly). Severe eating disorder should be treated before weight reduction is attempted.
    • Motivation: how are the patient's readiness , life situation and resources for accomplishing permanent lifestyle changes? Which of the existing habits already support weight maintenance? What kind of changes does the patient consider feasible?
  • Habits of life
    • Interview by nurse
      • Amount and type of food, meal times, snacks, use of alcohol and other energy-containing drinks
      • Eating behaviour: evening and night meals, eating for sorrow, binge eating
      • Type and amount of exercise.
  • Laboratory and other investigations
    • Blood pressure, fasting plasma glucose, HbA1c, plasma cholesterol, HDL cholesterol, LDL cholesterol, triglycerides and ALT are sufficient to screen for the most important associated diseases.

Evidence Summaries ⬆