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The clinical significance of obesity cannot be overstated; alongside increasing age it is the largest contributor to long-term morbidity in developed countries. In New Zealand one in three people (31%) are now obese and the prevalence is even more concerning among Pacific peoples (68%) and Maori (48%).

A healthy dietary pattern and regular exercise remain the cornerstones of obesity management. Medicines play a very limited role in the treatment of obesity and there are currently no anti-obesity medicines funded in New Zealand, although a number of newer medicines have been recently become available overseas.

To lose weight a person’s daily energy intake needs to be less than their daily energy expenditure. A daily energy deficiency of approximately 2500 kJ (600 calories) is recommended for most people wanting to lose weight. This equates to five slices of bread per day, or 2.5 cups of cooked rice or pasta. To maintain a stable weight, a female eating a healthy diet requires approximately 8400 kJ (2000 calories) per day and a male requires approximately 10 500 kJ (2500 calories) per day.

There is no difference in the weight-loss efficacy of diets with different macronutrient compositions, e.g. low carbohydrate diets or low fat diets, although there are adverse nutritional outcomes associated with some of these diets. This means that a person will lose weight on any diet that they are able to stick with, as long as energy consumption is less than energy expenditure. Therefore, the best health advice for someone trying to lose weight is that they eat a balanced and nutritious, calorie-reduced diet. Healthy dietary advice remains the same as it has for years: reduce sugar and saturated fat consumption, while increasing vegetables, whole grain cereals and fibre. What has changed in recent years is that international guidelines now allow people more choice in the relative amounts of macronutrients they can consume each day to achieve their daily energy intake. This means that nutritional guidelines can be translated into diets as diverse as the Mediterranean diet, with a relatively high amount of energy derived from unsaturated vegetable oils, to Asian-style diets which contain a relatively high carbohydrate intake.

People who wish to lose weight need to increase their energy expenditure as well as restricting their energy intake. Any increase in physical activity is likely to be beneficial. Health professionals play an important role in encouraging patients to overcome barriers to make exercise a permanent part of daily life, including:

  • Increasing self-efficacy
  • Negotiating weight-based and cardiovascular goals
  • Regular follow-up to monitor progress and provide ongoing support

Bariatric surgery is the most effective and sustainable weight-loss treatment for select patients who are morbidly obese, although it is reserved as a last-line of treatment. There are three gastric procedures commonly performed in New Zealand: adjustable gastric banding, sleeve gastrectomy, and roux-en-Y gastric bypass. Some degree of nutritional supplementation is required post-surgery depending on which procedure is performed. High-quality, long-term studies are required to determine exactly how successful this form of surgery is in assisting patients maintain long-term weight loss.

Peer group discussion points

  1. Do you find it difficult initiating discussions about weight-management with patients who are obese and if so, what are some of the strategies you use to overcome this?
  2. Do you often encounter misconceptions about diets and are there currently any “fad diets’ in particular that patients ask you about?
  3. Are there any features in common that you have noted in patients that have been able to maintain long-term weight loss? If so, do you think these qualities can be engendered in other patients?
  4. What strategies do you use to motivate patients to increase their levels of physical activity?
  5. Do you prescribe anti-obesity medicines and if so, which ones and how effective have you found them to be?
  6. Have you been involved in the care of any patients who have undergone bariatric surgery? If so, were these patients successful in maintaining long-term weight loss and how did it affect their quality of life?