TREATMENT
Dietary control This largely depends on a reduction in caloric intake. The most common diets allow a daily intake of approximately 4200 kJ (1000 kcal), although this may need to be nearer 6300 kJ (1500 kcal) for someone engaged in physical work. A diet that is too low in total calories will usually result in the patient cheating and keeping to the diet only for short periods. Patients must realize that prolonged dieting is necessary for large amounts of fat to be lost. Furthermore, a permanent change in eating habits is required to maintain the new low weight.
It is relatively easy for most people to lose the first few kilograms, but long-term success in moderate obesity is poor, with an overall success rate of no more than 10%. The aim of any dietary regimen is to lose approximately 1 kg per week. Weight loss will be greater initially owing to accompanying protein and glycogen breakdown and consequent water loss. After 3-4 weeks, incremental weight loss may be very small because only adipose tissue is broken down and there is no accompanying water loss. Patients must understand the principles of energy intake and expenditure, and the best results are obtained in educated, well-motivated patients. Constant supervision by a doctor, by close relatives or through membership of a slimming club helps to encourage compliance. An increase in exercise will increase energy expenditure and should be encouraged — provided there is no contra-indication — since weight control is usually not achieved without exercise. Weight cannot be lost by exercise alone, because even a 15-minute brisk daily walk will use less energy than is contained in a small slice of bread and butter. Regular exercise, however, will improve general health and often enables patients to control their diet. The diet should contain adequate amounts of each nutri-ent.
A diet of 4200 kJ (1000 kcal) per day should be made up of approximately 100 g of carbohydrate, 50 g of protein and 40 g of fat. The carbohydrate should be in the form of complex carbohydrates such as vegetables and fruit rather than simple sugars. Alcohol contains 29 kJ wl (7 kcal g-1) and should be discouraged. It can be substituted for other foods in the diet, but it often reduces the willpower. With a varied diet, vitamins and minerals will be adequate and supplements are not necessary. A balanced diet, attractively presented, is of much greater value and safer than any of the slimming regimens often advertised in magazines. Most obese people oscillate in weight; they often regain the lost weight, but many manage to lose weight again. This 'cycling' in bodyweight may play a role in the development of coronary artery disease.
Drug therapy Drugs can be used in the short term (up to three months) as an adjunct to the dietary regimen, but they do not substitute for strict dieting. Fenfluramine, which acts through the serotinergic system in the brain, has frequent
side effects. It has been associated with the development, albeit rarely, of primary pulmonary hypertension and valvular heart disease and, in the UK, along with dexfenfluramine, has now been withdrawn.
Surgical treatment Operations that involve bypassing parts of the small intestine have fallen out of favour because of their side-effects and cannot be recommended. Jejunoileal bypass was the most common operation and involved the anastomosis of approximately 18 cm of jejunum to the terminal 18 cm of the ileum. Complications are chiefly those of intestinal resection
. A fatty liver often occurs and in a few patients cirrhosis is seen. Three procedures are still performed in cases of severe morbid obesity:
• Hiring the jaws to prevent eating. This permits liquid feeds only. It can be used as a temporary measure but good dental hygiene is essential. Weight gain usually occurs after the wires have been removed, but this can be controlled by the use of a tight waist cord.
• Gastric plication. A small gastric pouch is created by stapling across the wall of the stomach. Good results have been claimed without the side-effects of bypass operations.
• Gastric balloon. A balloon is placed endoscopically inside the stomach and inflated. Its value has been over-exaggerated and complications include intestinal obstruction.
PREVENTION
Preventing obesity must always be the goal because most obese people find it difficult to maintain any weight loss they have managed to achieve. All health professionals must be aware of the dangers of obesity and encourage children, young as well as older adults, from gaining too much weight. A small gain each year over a long period produces an obese individual for whom treatment is difficult.
FURTHER READING
Nutritional support in the hospital patient
Nutritional support is recognized as being necessary in many hospitalized patients. The pathophysiology and hallmarks of malnutrition have been described earlier here the forms of nutritional support that are available are discussed.
Principles Some form of nutritional supplementation is required in those patients who cannot eat, should not eat, will not eat or cannot eat enough. It is necessary to provide nutri-tional support for:
• all severely malnourished patients on admission to hospital
• moderately malnourished patients who, because of their physical illness, are not expected to eat for
3-5 days
• normally nourished patients not expected to eat for 7-10 days. Enteral rather than parenteral nutrition should always be used if the gastrointestinal tract is functioning normally.
Enteral nutrition (EN) Feeds can be given by various routes:
• By mouth • By fine-bore nasogastric tube
• Percutaneous endoscopk gastrostomy (PEG) is useful for patients who need enteral nutrition for a prolonged period (e.g. more than 30 days), such as with swallowing problems following a head injury or in elderly people after a stroke. A catheter is placed percutmeously into the stomach under endoscopic control. • With needle catheter jejunostonty, a fine catheter is inserted into the jejunum at laparotomy and brought out through the abdominal wall.
—Misr Procedure
• Insert fine
•bore tube intranasally with wire stylet.
• Confirm position of tube in stomach by aspiration of gastric contents and auscultation of the epigastrium.
• Check by X
•ray if aspiration or auscultation is unsuccessful.
Problems No satisfactory way of keeping nasogastric tubes in place (up to 60% come out). Main complications
• Regurgitation and aspiration into bronchus
• Blockage of the nasogastric tube
• Gastrointestinal side-effects, the most common being diarrhoea
• Metabolic complications including hyperglycaemia and hyperkalaemia, as well as low levels of potassium, magnesium, calcium and phosphate.
Diet formulation
A polymeric diet with whole-protein and fat can be used, except in patients with severely impaired gastrointestinal function who may require a predigested (i.e. elemental) diet. In these patients, the nitrogen source is purified low-molecular-weight peptides or amino acid mixtures, with sometimes the fat being given partly as medium-chain triglycerides.
MANAGEMENT
The aim of any regimen is to achieve a positive nitrogen balance, which can usually be obtained by giving 3-5 g of nitrogen in excess of output. Nitrogen loss can be calculated using the formula: N2 loss (g per 24 hours) = Urinary urea (mmol per 24 hours) x 0.028 + 2 (the 2 representing non-urinary nitrogen excretion). Daily amounts of diet vary between 2 and 2.5 L and the full amount can be started immediately. Hypercatabolic patients require a high supply of nitrogen (15 g daily) and often will not achieve positive nitrogen balance until the primary injury is resolved. The success of enteral feeding depends on careful supervision of the patient with monitoring of weight, biochemistry and diet charts.
Total parenteral nutrition (TPN) Peripheral parenteral nutrition Specially formulated mixtures for peripheral use are available, with a low osmolality and containing lipid emulsions. Heparin and corticosteroids are added to the infusion and local application of glyceryl trinitrate patches reduces the occurrence of thrombophlebitis and prolongs catheter life. Initially, peripheral parenteral nutrition is preferred (each catheter will last for about 5 days), allowing time to consider the necessity for having to insert a central venous catheter.
Standard enteric diet, providing 12 000 Id per day (2000-3000 kcal)
Energy Carbohydrate as glucose polymers (49-53% of total energy) Fat as triglycerides (30-35% of total energy)
Nitrogen Whole protein (6-7 g of nitrogen L71) Additional electrolytes, vitamins and trace elements
Features Ratio of energy to nitrogen kJ:g = 620:1 (kcal:g = 150:1) Osmolality = 285-300 mOsmol kg-I
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