OBESITY

WHAT IS OBESITY ?

Obesity can be defined as a condition of excess body fat, where fat has accumulated to an extent that is likely to be detrimental to health.

Body Mass Index (BMI) is a measure of overweight and obesity and is calculated as follows:

For example, an adult of height 174cms, weight = 70kg has a BMI of :

The internationally accepted ranges of BMI are:

Obesity occurs when the body is sustained in positive energy balance energy where the amount of energy (calories) eaten in the form of food is more than the energy used and needed by the body for life and daily activities.

Many factors are important in the development of obesity such as behavioural influences, physiological, environmental and psychological factors. All of which should be addressed in the treatment of this complex disease.

Occasionally obesity is caused by a disease such as Cushings Disease or hypothyroidism but this is very rare ( less than 1% of obese population). Drugs used for some medical conditions can promote weight gain, for example, antidepressants, steroidal contraceptives, corticosteroids.

Recent figures show that in the UK around 40% of the population are overweight, 18 % of which are obese. These figures have doubled in the last 10 years.

The risks of developing many other medical complaints are significantly increased by obesity:

Table showing relative risk of health problems associated with obesity

The main benefits of a modest weight loss (10 % loss of initial weight) are summarised below:

For successful long term treatment of obesity permanent changes must be made in :

These changes are necessary not only to lose weight but to maintain the loss of weight for life. These changes should be made for life and patients should not feel they are following a temporary diet as when this 'temporary diet' is finished then weight regain will follow. Temporary restriction of specific foods are not effective in maintaining long term weight loss.

There are various diets available in both the hospital and commercial setting. The information provided here covers available treatments in both the hospital and commercial setting.

(i) Individualised modest energy restrictive diet - widely available*
(ii) Prescriptive / fixed energy restricted diet - widely available*
(iii) Very Low Calorie Liquid Diet - medical supervision only

*Diets based on healthy eating principles should always be used as a first line treatment and are safe to be started without medical supervision. The other treatments are used in the specialist centre at Ninewells Hospital and should not be undertaken without strict medical supervision.

Diets based on healthy eating with modest reductions of energy should always be used as a first line treatment of obesity and overweight in combination with a change in eating behaviour and lifestyle. Most diets are based on the principles of healthy eating (typically low fat, low sugar, high fibre). The individualised diets are calculated based on the nutritional requirements of a person taking account of age, weight, sex and activity level. The diet prescribed provides 600 calories less than calculated nutritional requirements which will induce effective and desirable levels of weight loss. These diets should be appropriately restricted in energy (calories) but still provide the correct balance of all nutrients and aim to achieve modest weight loss.   Such prescriptions can mostly be adapted to suit individual preferences and lifestyle. Diets based on healthy eating principles and modest reductions of energy are safe, more compatible with everyday living therefore easier to adhere to and have the best chance at long term success. The individualised diet sheet used in the obesity clinic at Ninewells is 'weight loss on a plate' (produced by state registered dietitians). This resource allows the tailored prescription of individualised diets ranging from 1200 calories to 3000 calories depending on individual needs. An example of this dietary prescription is shown in appendix 1.

These diets are prescribed regardless of the individual's age, weight or habitual intake. Suggested diets are commonly between 1200 - 1400 calories daily and have less flexibility which can be an advantage in individuals who need more direction and find flexibility difficult to control.

In appendix 2 there is an example of a prescriptive diet used at Ninewells Hospital, Obesity Clinic when a more restrictive diet is necessary. This prescribes 1300 calories daily.

NB. Any diet prescribed by a state registered dietitian will be tailored to individual requirements. Most reputable commercial slimming organisations provide diets suitably based on the above principles and are widely available.

(iii)Very Low Calorie Liquid Diet (VLCD) - strict medical supervision

VLCD should be reserved for very obese individuals who need to lose weight rapidly for health reasons and should only be used under strict medical supervision. The use of VLCD should be considered only after the failure of determined attempts to lose weight with conventional diets.

VLCD are liquid based diets that are severely restrictive in energy. The energy (calorie) content of these diets are usually less than 800 kcal / day. The diet is supplemented to be nutritionally complete in all other aspects. Any liquid diet should not be used on a long term basis, at Ninewells Hospital they are used for a limited period of three months. The VLCD can induce weight loss of 1.5 - 2.5 kg per week leading to approximately 20 kg over the duration of the course. Some weight is usually regained after the VLCD is stopped but correct supervision and dietary advice helps to combat this. There are some medical conditions that VLCD should not be used / be used with caution under strict medical supervision :

The nutritional composition of VLCD must be carefully considered. Ideally all slimmers would wish to lose only fat tissue when losing weight. The more restrictive the calories are, the greater the loss of non - fat tissue from the body. To minimise the potential risks from undue loss of non - fat tissue and to prevent nutritional deficiencies VLCD preparations should contain a minimum of 500 calories, 50g of high biological value protein, a source of carbohydrate also a vitamin, mineral and iron supplement.

Overeating associated with overweight and obesity is the result of food and food related habits/behaviour. Behavioural therapy helps patients to become more aware of their eating and lifestyle behaviour and examines the trigger factors that cause bad habits to develop. Behavioural changes should aim to alter behaviour in the long term which will help maintain a more healthy weight.

Positive behavioural changes to be addressed :

• Keeping a food diary and self monitoring

• Looking for ways to increase daily exercise (within personal limitations)

• Planning daily / weekly food plans

• Planning for shopping trips

• Preparing for special occasions

• Learning how to cope with small lapses to prevent full relapse

• Identifying personal trigger situations that lead to poor eating habits and look at ways to

combat these

• Exploring whether stress may lead to overeating and identify alternative ways to cope

with stress

• Setting realistic goals - short and long term

Any weight management programme should include an increase in physical activity / exercise wherever possible. Exercise helps to speed up and maintain weight loss and may assist with promoting a healthier fat distribution across the body. Exercise can also help manage some of the complications of and medical conditions related to overweight and obesity.

· Increases amount of energy (calories) used up by the body

· Improves the fat distribution - reduces fat stored around the stomach

· Helps to control and regulate the appetite

· Improves muscle function and strength

· Reduces insulin resistance (insulin resistance can lead to development of diabetes)

· Reduces blood pressure

· Improves fitness levels

· Helps to make you feel great !

Drug Therapy - medical supervision only

Drug therapy should only be considered for use when diet, exercise/behavioural modification have failed and the health of the patient is at severe risk. Drugs do not remove the need for full dietary compliance, they only help with maintaining compliance. Even after initiation of the drug dietary advice must be followed. Diet remains at the centre of the success of any treatment. There are a limited number of drugs available for the treatment of obesity due to a recent withdrawal of appetite suppressants (dexfenfluramine and fenfluramine) from the drug market due to concerns about the safety of their use.

The only drug currently available is Orlistat (Xenical^TM). This drug acts by preventing and interfering with the body's natural process for the digestion and absorption of fat eaten in the diet. The drug has been designed to target fat as fat is one of the main contributors of too many calories in the diet. If too much fat or too many fat rich foods are eaten while taking Orlistat this will lead to severe gastrointestinal symptoms such as loose / liquid stools, incontinence, oily discharge and flatulence. Having had these unpleasant and undesirable side effects the experience actually helps patients to comply with a low fat healthy diet in order to avoid their reoccurrence. Orlistat only blocks 30% of ingested fat which allows sufficient absorption of dietary fat and nutrients needed to maintain good health.

In the region of Tayside the area drug and therapeutics committee have produced guidelines for the use and prescription of Orlistat (Xenical^TM). These guidelines have been produced to ensure this drug is used only in appropriate situations, that patients will have the correct information on its usage and the best chance of successful weight loss following its prescription. These guidelines suggest that prescription of Orlistat should only be approved if patients have been entered into a structured weight management programme, have demonstrated their commitment and ability to lose weight and follow a low fat diet. In addition the guidelines suggest that if weight loss does not reach a recommended level following prescription of the drug, the prescription should be stopped.

Surgical Treatments

Surgical procedures for the treatment of obesity are only undertaken in severely obese patients with a BMI >40 kg/m² (or >35 in the presence of one or more co - morbid risk factor) and only after alternative dietary, lifestyle and drug treatments have failed. The common surgical procedures undertaken in this country are :

A small pouch is created at the entrance to the stomach by inserting surgical staples into the stomach walls. The pouch contains a small outlet that will empty into the rest of the stomach. When the patient eats or drinks this pouch fills rapidly therefore only permits small amounts of food or liquid to be consumed at any one time. Any additional food / liquids are refluxed into the gullet.

This involves wrapping a silicone band around the outside of the stomach to form a smaller pouch at the entrance to the stomach and a small outlet which will empty into the rest of the stomach. This pouch restricts the volume of food and liquid that can be consumed at any one time. Any additional food / liquids are refluxed into the gullet.

The incidence of post operative complications with all surgical procedures related to obesity are high therefore careful medical, surgical and nutritional supervision is needed both before and after surgery to prevent potential nutritional or digestive complications. These surgical procedures are only undertaken in specialist centres across the country where funding permits.

Where can I get additional information?

http://www.hebs.scot.nhs.uk/learningcentre/weightmanagement
www.niddk.nih.gov/health/nutrit/nutrit.htm

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Ó NHS Tayside; 2006; version 1.0

Disclaimer; no liability whatsoever is accepted for information given and all such information, especially with regard to drug usage (UK version provided), must be checked with a person’s health provider.