Prescribing for obesity

Sometimes willpower is simply not enough for patients to achieve the weight loss they need. So what advice can you offer to patients who are clinically obese?

Obesity is defined as a body mass index of 30 kg/m2 or above, with a BMI of 25 - 29.9 kg/m² being considered overweight. More than half of adults in the UK are overweight and nearly a quarter of adults are obese,¹ with this trend increasing over the past few years. This is of concern given that obesity is associated with significant co-morbidities such as hypertension, coronary heart disease, type 2 diabetes, gallstones, various cancers and reduced life expectancy.² It can also aggravate pre-existing conditions such as osteoarthritis. So this rising trend is an increasing public health problem that needs addressing, but it is also an area where offering truly person centred care rather than generalised approaches is most likely to be effective at an individual level.

Consider Alice, a 38-year-old woman. Alice has gradually put on weight over the past few years since the birth of her two children. She is now keen to address this, as her children have both recently started school, and has come to ask your advice regarding this. What would you consider at your initial assessment?

Alice's initial assessment will be complex, so you need to make sure that you allow enough time for this, as the aim is for you to empower Alice to make the lifestyle changes needed to address her weight. Obviously you will need to measure her BMI to be able to understand the extent of her problem and also to be able to track her progress over time. There is also evidence that the risk of developing co-morbidities such as diabetes is influenced by the distribution of the excess fat so waist circumference is a helpful measurement to consider, particularly in those with a BMI < 35kg/m². In women a waist circumference of > 88cm is considered very high, in men it is a waist circumference of > 102cm.³ In order to prevent embarrassment ensure that the tape measure you are using is long enough before attempting to use it for measurement. You also need to measure Alice's blood pressure, ensuring that you use an appropriately sized cuff.

You then need to ascertain whether there is any medical reason why Alice may be overweight. Patients are often keen to blame some external influence such as 'my glands' for their weight problems whereas it is more usually a mismatch between their calorific input and their expenditure: the old adage 'eat less, exercise more' often holds true. However, there will be a small minority of patients for whom there is a contributing medical condition such as hypothyroidism. Routine blood screening for this at the first assessment is not recommended but you should enquire about any family history of the condition as well as other potential symptoms. Other reasons that may be contributing to Alice's weight problem include medication, particularly antidepressants and some forms of contraception. It is worth recognising that depressive and anxiety symptoms are common in the obese population4 as many people turn to food as a comfort in times of stress.

You then need to ascertain Alice's current eating patterns and exercise regimen as well as her motivation for change. This will include enquiring about previous attempts to lose weight and what she may have already tried on this occasion. In this way it is very similar to the motivational interviewing techniques used in other health promotion situations such as smoking cessation. This is one of the most important aspects of the initial assessment and will take considerable time. (Box 1)

Alice has a BMI of 30kg/m² and a waist circumference of 84cm. Her husband is also overweight. She also smokes 20 cigarettes/day. She does not do any formal exercise but she does walk her two children to school sometimes, which is about a 2 mile round trip. She is keen to lose weight now as her sister is getting married later in the year and she wants to look good in the wedding photos, having been shocked by her holiday photos last year.

Alice's BMI and waist circumference put her at high risk of complications from her weight so it is probably worth screening her for co-morbidities by undertaking a fasting glucose and lipid profile. NICE² advocates treating these co-morbidities as soon as they arise rather than waiting for weight loss, although clearly the initial management of type 2 diabetes may well include weight loss. However, the presence of co-morbidities might influence the management of Alice's obesity. Alice should also be entered on the practice's obesity register as this forms part of the Quality and Outcomes Framework.

Alice has good foundations for being able to lose weight although she may not recognise this herself. She does not consider that she does any exercise yet walking the children to school is clearly exercise and so encouraging her to do this more often and perhaps to try and walk faster on the return journey without the children are good suggestions. Getting patients to incorporate lifestyle changes into their existing regimen is much more likely to be successful than advocating whole scale change in terms of maintaining weight loss in the long-term.

Alice also needs to be realistic in terms of the weight loss that she can expect, and the recommended rate of weight loss is just 1-2 lbs per week.² This can be achieved by a calorie intake that is 600 kcals than that which she needs to maintain her current weight. She also needs to recognise that slips or binges are common and that this should not lead her to give up completely, but rather to reframe her thinking so that she perseveres. Given that her husband is also overweight getting him on board with a weight loss programme may well help support Alice as well as improve his own health.

Alice's smoking is also of concern in terms of her long-term health and is more likely to be detrimental to her at this point than her weight. However, smoking cessation is often associated with modest weight gain. For most patients advocating dieting and smoking cessation simultaneously is unrealistic. You need to take your cue from Alice as to which is her current priority whilst taking care not to condone smoking as a means of weight maintenance.

Alice shares with you that she has been doing some research on the Internet and she has been reading about some herbal preparations that help weight loss. She would like to know what you think about trying these.

Many overweight patients seek a quick fix to their situation. Our clear role as health professionals is to help them make an informed choice in their situation by:⁶

• Sharing what we know works
• Building confidence in their ability to lose weight
• Share our concerns if we think the choice they are making is a poor one

This means that we need to have some awareness of the options available for patients, including those advertised on the Internet. Capsaicin (pepper extract) and hoodia (cactus extract) both have some generic evidence that the raw ingredient may induce weight loss but not in the formulations available.⁷ Some weight loss products may even be related to amphetamines and so are actively associated with health risks, not just an absence of benefit. In IT literate patients it is worth signposting them to reputable websites such as www.patient.co.uk. It is also worth familiarising yourself with some of the common commercially available weight loss programmes such as Weightwatchers and Slimming World so that you can engage in meaningful discussion about their use.

Alice's blood results come back showing that she has a fasting glucose of 7.2 g/dl and fasting cholesterol of 5.6, HDL 1.3 and LDL 4.3. She has been trying to increase her exercise and decrease her calorie intake and has been modestly successful having lost 3 lbs. in the past month.

Alice should be encouraged by her progress as she is losing weight at an appropriate rate, but she has already developed comorbidities as a result of obesity. Hence offering Alice an anti-obesity drug may be an appropriate next step in this instance. (Table 1)

The only anti-obesity drug currently available in the UK is orlistat (brand name Xenical). There have been two alternatives available in the past but both have been withdrawn - sibutramine due to concerns about its cardiovascular safety and rimonabant due to concerns about its psychiatric effects. Orlistat is used as an adjunct to dietary and exercise advice in individuals with a BMI of > 30kg/m2 in whom at least 3 months of behaviour modification has failed to achieve a realistic reduction in weight. It is also advocated in those, like Alice, who have a BMI of > 27kg/m2 and established risk factors.

Orlistat has been available since 1998. It is an inhibitor of gastrointestinal lipase enzymes, which normally catalyse the hydrolysis of dietary fat. Consequently it reduces fat absorption, resulting in a loss of 25 - 35% dietary fat in the faeces compared to around 5% loss with placebo. The usual dose is 120mgs three times daily, however it is now also available over the counter as alli, at a dose of 60mgs three times daily under pharmacist supervision. It is thought that this lower dose has about 85% of the efficacy and 50% of the side effects of the prescription dose.⁷ A month's prescription of orlistat costs around £30 - £35.

The main side effects of orlistat are gastrointestinal, such as oily spotting from the rectum, flatus with discharge, faecal urgency and fatty or oily faeces. These effects ameliorate with time as patients get used to the low fat diet needed to avoid them, and any patient with persistent symptoms could be gently challenged as to their continued dietary fat intake. The manufacturing company offers an excellent support line, including suitable recipes, which patients should be encouraged to make use of in combination with the prescription.

Orlistat also reduces absorption of fat-soluble vitamins (A, D, E, K) and beta-carotene although this does not seem to be of clinical significance in patients with a reasonable diet. If a patient is thought to need supplementation then this needs to be taken at least 2 hours after orlistat or at bedtime. Interestingly, orlistat does not seem to interact with lipophilic drugs such as fluoxetine and simvastatin.

Orlistat is contraindicated in patients with chronic malabsorption syndrome or cholestasis and in women who are pregnant or breastfeeding. It is also worth remembering that persistent gastrointestinal symptoms may influence the efficacy of some forms of oral contraception.

In Alice, orlistat may well help to attenuate her weight loss but needs to be used in combination with continuing behavioural modification and support. NICE² recommends continuing for longer than 3 months only if the individual concerned has lost 5% of their initial body weight since starting drug treatment, although the targets are slightly less stringent for those like Alice who have type 2 diabetes. It is continued after 12 months, usually for weight maintenance, in a small minority of patients with whom the potential benefits and limitations have been discussed.

CONCLUSION

It is worth remembering that not all obese patients will be like Alice and actively seek help for their problem. Yet many patients with co-morbidities like hypertension and chronic obstructive pulmonary disease would also benefit from weight loss advice, and so obesity screening should form part of their regular reviews of treatment. If you are developing a formal role in weight management as part of your practice then you should probably also familiarise yourself with bariatric surgery⁸ and very low calorie diets² as these also have a role, particularly for those who are significantly obese.

REFERENCES

1.Benninger M., Segreti J (2008) Is it bacterial or viral? 1. Statistics on Obesity, Physical Activity and Diet: England, 2011 accessed at: http://www.ic.nhs.uk/pubs/opad11 (accessed June 2011)

2. NICE. Obesity: the prevention, identification, assessment and management of overweight and obesity in adults and children. NICE 2006: CG43.

3. Why & How should adults lose weight? Drugs & Therapeutics Bulletin Vol 36. No 12. Dec 1998. pp 89 - 92.

4. Tuthill A et al. Psychiatric co-morbidities in patients attending specialist obesity services in the UK. QJM: An International Journal of Medicine 2006: 99: 317 - 25

5. Obesity in Adults accessed at http://www.patient.co.uk/doctor/Obesity-Management-in-Adults.htm (accessed June 2011)

6. Anstiss, T & Fry M Cardiovascular risk: Key Questions - Lifestyle changes Pulse 13 April 2011 pp19-23

7. Haslam, D & Fry M Key Questions - Obesity Pulse 23 March 2011 pp18-19

8. Surgery for Obesity in Adults Drugs & Therapeutics Bulletin Vol 46. No 6. June 2008. pp41 - 45