ARTICLE
blood are required to promote removal of calories from the bloodstream in the post- prandial state; hence the characteristic hyperinsulinaemic state of many obese patients and type 2 diabetics. The biochemistry of appetite control and satiety is complex. Ingestion of calories is driven by a wide range of social and personal factors. Food intake is often utilised to assuage feelings of loneliness, boredom, anger or grief and is also utilised to celebrate significant life and personal events. In our society, the intake of food has taken on a significance much greater than addressing hunger; consequently, it has become more difficult to address the causes of excess intake, which are also correspondingly much more complex in our society. It is clear that appetite control is a complex phenomenon, involving both ‘higher’ and ‘lower’ brain centres, and is not explicable in any simplistic way given our current understanding of neural pathways and interactions.
On the basis of new understanding of the biochemistry of appetite control, new classes of pharmacological agent to reduce appetite have been introduced to the market, and have met with varying degrees of success. The complexity of the biochemical processes involved in the central control of food intake is evidenced by the difficulty in finding agents that specifically reduce appetite without causing unacceptable side effects. Newer agents discussed below offer greater prospect of long-term success and are largely based on the role of intestinal hormones as satiety inducing agents.
TREATMENT OF OBESITY There is general agreement that the ‘conventional’ approach of giving advice, often braced with threats of imminent death and numerous leaflets, has failed. Newer non-pharmacological approaches have achieved much greater success in achieving and maintaining clinically significant degrees of weight loss. A standard benchmark of meaningful weight loss for any interventional programme to address obesity is generally set at about 5% of initial weight. Successful non-pharmacological
approaches to weigh management are generally based on behavioural modification techniques. Such psychologically-based therapies, initially developed for drug addiction treatments, can be successfully adapted to weight loss. The premise is basically that the patient’s relationship with food has become pathological, and for these patients, food, like drugs, is being used to address some otherwise unsatisfied need in their lives. Behavioural modification therapies (BMT) aim to identify that need and provide other, less damaging means of addressing the need. Behavioural modification is a very successful approach to weight modification in appropriate patients, particularly those patients with a weight-related co-morbidity such as type 2 diabetes. However, BMT therapists require
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specific training to be successful and achieve the results found in the clinical trials. Often, BMT can be combined with other pharmacological and non-pharmacological therapies to achieve greater degrees of weight loss. In our own practice, a BMT programme (Motivate) achieves an average of 7% weight loss over six months that is maintained for at least two years. Particularly successful applications of BMT combined with either lifestyle or pharmacological treatments is in the area of the prevention of the development of type 2 diabetes in high-risk obese individuals. A relative risk reduction of almost 60% in progression to type 2 diabetes can be achieved.
Appetite reducing drugs The introduction of glucagon-1-peptide agonists has transformed practice and prognosis for the obese type 2 diabetic patient. This class of agents is based on the ‘satiety peptide’, glucagon-like peptide-1 (GLP-1), and they are licensed (in general) for type 2 diabetics not receiving insulin, although the indications are likely to broaden as more experience is gained in clinical practice. GLP-1 is secreted from the stomach and small intestine following ingestion of food. GLP-1-based agents induce satiety and hence reduce calorie intake, leading to weight loss. Secondary gains include a reduction in HbA1c for poorly controlled diabetics. Nausea can be an issue for some patients but this is generally transient.
A major limitation of these agents is that
they require to be injected subcutaneously – a drawback for some patients – and their licence is limited for use in those patients who have already developed type 2 diabetes. GLP-1 agents can be combined with BMT for appropriate patients and result in approximately double the degree of weight loss achieved by BMT alone in type 2 diabetics.
In our own practice, the combination of
BMT and GLP-1 agonist in type 2 diabetes, introduced in 2009, addressed the continuing increase in the proportion of obese patients seen using conventional dietetic approaches, and reduced the prevalence of obesity in that population from 49% to 26% within two years.
Surgical approach Bariatric surgery is also an option for more severely affected patients, with sleeve gastrectomy or gastric banding being the most popular procedures. Bariatric surgery achieves impressive weight loss in severely obese patients and can effectively cure type 2 diabetes in many patients. Unfortunately, the surgical route is not appropriate for mass use as it carries significant morbidity and mortality. Furthermore, as the psychological drivers for excess food intake are often not addressed appropriately in the surgical careplan, many patients remain ‘dissatisfied’ despite very significant weight loss, and the anticipated social or personal benefits of weight loss are not realised. A major problem is that, despite the
proven success of BMT, GLP-1 agonists and bariatric surgery, there is no comprehensive access to, nor availability of, appropriately trained and quality-assured programmes of care for the population affected. Weight modification programmes are cost-effective and clinically effective. In our own practice, the cost per patient for BMT is approximately £100 per patient and the net savings, estimated in terms of overall utilisation of healthcare resources, is £500 per patient.
BENEFITS OF WEIGHT LOSS The personal, psychological and clinical benefits of weight loss for obese patients are not in doubt. Calorie restriction, self-imposed or imposed externally, achieves real reductions in death rates within a short timescale.
The benefits of weight loss accrue for affected patients at any age and any degree of
THE BIOMEDICAL SCIENTIST 701
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