Obesity Flashcards
Investigations
1.TFTs (Thyroid function tests) performed.
2.An overnight dexamethasone suppression test or 24-hr urine
free cortisol if Cushing’s syndrome is suspected.
3.Assessment of other cardiovascular risk factors is important.
4.BP (Blood pressure) should be measured.
5. Type 2 diabetes and dyslipidaemia detected by measuring blood
glucose and serum lipids.
6. Elevated transaminases suggest non-alcoholic fatty liver disease.
Lifestyle advice
o Maximise their physical activity by incorporating it into
the daily routine (e.g. walking rather than driving to
work).
o Changes in eating behaviour (including portion size
control, avoidance of snacking, regular meals to
encourage satiety, and use of artificial sweeteners)
should be discussed.
Weight loss diets
Weight loss diets require a reduction in daily total energy intake of ~2.5 MJ
(600 kcal) from the patient’s normal consumption.
• The goal is to lose ~0.5 kg/wk.
In some patients more rapid weight loss is required, e.g. in preparation for
surgery.
• There is no role for starvation diets, which carry a risk of sudden death from
heart disease.
• Very low calorie diets produce weight loss of 1.5–2.5 kg/week but require the
supervision of a physician and nutritionist.
Drugs
• Drug therapy is usually reserved for obese patients with a high risk of
complications.
• Patients who continue to take anti-obesity drugs tend to regain weight with time.
o It is recommended that anti-obesity drugs are used short-term to maximise
weight loss in patients who are demonstrating their adherence to a low-calorie
diet by current weight loss.
• Several drugs have been withdrawn due to side-effects, and orlistat is the only
drug currently licensed for long-term use.
Orlistat mechanism
inhibits pancreatic and gastric lipases, reducing dietary fat absorption by
~30%. Side-effects relate to the resultant fat malabsorption: namely, loose stools,
oily spotting, faecal urgency, flatus and malabsorption of fat-soluble vitamins.
Complications of obesity
● Metabolic syndrome.
● Non-alcoholic steatohepatitis.
● Cirrhosis.
● Sleep apnoea.
● Osteoarthritis.
● Psychosocial disadvantage.
● Obesity has adverse effects on both mortality and morbidity; life expectancy
is reduced by 13 years amongst obese smokers.
● Coronary artery disease (CAD) is the major cause of death.
● Some cancer rates are also increased (Endometrial cancer).
Undernutrition is caused by
❑ Decreased energy intak
❑ Increased energy expenditur
❑ Decreased energy intak
- Famine.
- Persistent regurgitation or vomiting.
- Anorexia.
- Malabsorption (e.g. small intestinal disease).
- Maldigestion (e.g. pancreatic exocrine insufficiency).
❑ Increased energy expenditur
- Increased basal metabolic rate (BMR; thyrotoxicosis, trauma, fever, cancer
cachexia). - Excessive physical activity (e.g. marathon runners).
- Energy loss (e.g. glycosuria in diabetes).
- Impaired energy storage (e.g. Addison’s disease, phaeochromocytoma).
• The clinical features of severe under-nutrition in adults include :
o Loss of weight.
o Thirst, weakness, a feeling of cold, nocturia, amenorrhoea, impotence.
o Lax, pale, dry skin.
o Hair thinning or loss.
o Cold, cyanosed extremities, pressure sores.
o Muscle-wasting.
o Loss of subcutaneous fat.
o Oedema (even without hypoalbuminaemia).
o Subnormal body temperature, slow pulse, low BP.
o Distended abdomen, with diarrhoea.
o Diminished tendon jerks.
o Apathy, loss of initiative, depression, introversion, aggression if food is nearby.
o Susceptibility to infections.
Investigations
- Plasma free fatty acids are increased, with ketosis and a mild metabolic
acidosis. - Plasma glucose is low but albumin is often maintained.
- Insulin secretion is diminished, glucagon and cortisol increase, and reverse
T3 replaces normal triiodothyronine. - Resting metabolic rate falls, due to reduced lean body mass and
hypothalamic compensation. - There may be mild anaemia, leucopenia and thrombocytopenia.
• Patients should be graded according to BMI.
o Those with moderate starvation need extra feeding.
o Those who are severely underweight need hospital care.
• In severe starvation there is atrophy of the intestinal epithelium and the exocrine
pancreas.
o Small amounts of food should be given at first; it should be palatable and similar to
the usual staple meal, e.g. cereal with some sugar, milk powder and oil.
o Salt should be restricted and micronutrient supplements may be essential (e.g.
potassium, magnesium, zinc and multivitamins).
o Between 1500–2000 kcal/day will prevent deterioration, but additional calories are
required for regain of weight.
o During refeeding, a gain of 5% body weight/month indicates satisfactory progress.
o Other measures are supportive, and include care for the skin, adequate hydration,
treatment of infections, and careful monitoring of body temperature since
thermoregulation may be impaired.
• Many patients lose weight in hospital due to
- Poor appetite.
- Concurrent illness.
- Being kept ‘nil by mouth’ for investigations.
• Undernutrition in hospital leads to:
o Impaired immunity.
o Muscle weakness.
o Increased morbidity, mortality.
o Increased length of stay.
