Weight management: lifestyle services for overweight or obese adults

The PDG considered that the overarching approach to lifestyle weight management should be to do no harm.

Generally, the more weight an adult loses as part of a lifestyle weight management programme, the more health benefits they are likely to gain. (For example, they could benefit from reducing their blood pressure or improving control of blood glucose levels.) A commonly stated 'realistic' goal is to lose around 5–10% of baseline weight. The evidence reviews for this guideline estimated that the mean percentage weight loss from participating in a lifestyle weight management programme was somewhat lower, with an average of around 3% of baseline weight. However, the PDG noted that even losing this relatively small amount of weight is likely to lead to health benefits (particularly if the weight loss is maintained for many years).

Observed weight losses from multicomponent lifestyle weight management programmes (as identified in the evidence review) are unlikely to be associated with unintended or adverse effects. (For example, musculoskeletal injuries or increased anxiety.) But the PDG noted that any unintended or adverse effects were not actively investigated, or systematically reported, in the majority of trials reviewed.

The PDG heard that people who are obese may perceive or experience stigma on a daily basis, and that any failure to lose weight (or regaining weight following weight loss) may have a negative psychological effect. Although this should not be a reason to avoid managing weight, it does highlight the importance of adopting a respectful, non-judgemental approach. It also highlights the importance of providing long-term support. The PDG noted that it is vital people are enabled to make informed choices about if, when and how they manage their weight. Training and continuing professional development is, members believe, particularly important in both these contexts. The Group also noted that the type and level of training for weight management programmes varies substantially. In particular, healthcare professionals have reported concerns about their lack of training or confidence in raising the issue of weight management.

The PDG considered a substantial body of evidence, including 29 randomised controlled trials of lifestyle weight management programmes lasting at least 12 months. Seven of the 29 trials reported outcomes at 3 years or longer. But no studies were identified with outcomes beyond 5 years. Maintaining weight loss is known to be difficult and, as a result, extrapolating longer term outcomes from short term studies may be misleading. Modelling showed that even a small amount of weight loss is cost effective, but only if it is maintained long term on a lower weight trajectory.

The PDG concluded that multicomponent lifestyle weight management programmes that address dietary habits, physical activity and behaviour change techniques can help adults lose weight and maintain that weight loss for at least 12 to 18 months. However, it was difficult to draw conclusions about why some programmes were more effective than others, or about the effect of specific components. (Examples of the latter include: the setting, face-to-face versus remote contact and the effect of the length or intensity of a programme.) Few studies reported outcomes for specific groups and it was unclear what any reported 'tailoring' meant in practice.

The PDG noted that obese adults may attempt to lose weight many times throughout their lives. The point at which they may be successful (and the number of times this translates into a referral to services) was unclear. In addition, the effect (both positive and negative) on their psychological or physical health remains unclear. The PDG agreed that people who are obese need as many opportunities as possible to lose weight. Members also agreed that this should be an ongoing area for research.

The PDG was unable to consider the relative effectiveness of alternative approaches to weight management – such as focusing on a healthy lifestyle and the prevention of weight gain rather than weight loss – because of a lack of trials that met the review inclusion criteria.

The PDG noted the lack of longer term follow-up of a range of approaches to weight management and the lack of standard evaluation of trials. This includes standard reporting of weight outcomes and strategies for dealing with missing data for different groups to judge the effect on inequalities in health. It has made a research recommendation on this to improve the evidence base.

The guideline focused on multicomponent lifestyle weight management services and excluded other routes for managing obesity, such as drugs or surgery. Evidence that focused only on populations with linked conditions (such as type 2 diabetes) was excluded, as was evidence on people with more complex needs (such as those who are obese and also have alcohol or mental health problems). The relative effectiveness of, for example, specific dietary approaches or the effect of wider behaviours that have been linked to weight gain (such as shift working or sleep) was not considered. Therefore it is important to read this guideline in the context of broader NICE guidance on obesity.

The PDG noted that local services or activities that address the wider determinants of health may also help people to change their dietary habits or physical activity levels and manage their weight.

The PDG was concerned that people who have attended weight management services may not have enough sources of support to prevent them regaining the weight they have lost. Members recognised the importance of commissioned services addressing the prevention of weight regain. The evidence reviewed suggests that commercial multicomponent lifestyle weight management programmes available in the UK are likely to be effective, at least up to 12 to 18 months. However, this finding is based on a relatively small number of trials and no head-to-head comparisons of the relative effectiveness of programmes were available. The evidence reviewed also suggests that primary care-led services may be less effective than commercial programmes, but it is unclear why. The PDG noted that local authority services may be established to support people living in particular geographic areas, or from lower income groups. This is particularly the case if their needs are not being met by commercial programmes.

The PDG discussed the importance of ensuring commissioners have access to robust, regularly updated information on effective lifestyle weight management programmes. Members noted how time consuming and potentially difficult it would be otherwise for each local area to decide which programmes may be most effective and cost effective. It was noted that programme range, content and evidence of effectiveness may be subject to change. They agreed that a national source of information on programmes shown to be effective – based on robust and consistent data – would be helpful. The PDG's conclusions were informed by the randomised controlled trials of programmes included in the evidence reviews. Members noted that it was unclear what impact any subsequent changes made to the format or content of programmes would have on effectiveness.

The PDG noted that the ability to review, improve or decommission programmes at a local level is dependent on monitoring processes being built into the programme from the outset. Members also agreed that establishing systems for information sharing between referrers and providers (such as weight outcomes at programme end or at 12 months) was key.

The PDG was concerned that people from lower income groups may struggle to attend programmes once their referral period is over. This is a particular concern if participants wishing to continue the programme beyond the referral period have to pay for it.

The PDG noted the importance of an integrated approach to weight management to ensure referrals can easily be made within and across different tiers of weight management services. In addition, because some people who are obese may have other health issues, it noted the importance of local links between a variety of services. (This includes, for example, weight management, smoking cessation, mental health services, substance misuse and alcohol counselling services.)

The PDG noted that the recommendations in this guideline apply equally to all types of lifestyle weight management programme.

The economic model estimated that a 12-week programme costing £100 or less will be cost-effective for adults who are overweight or obese under 2 conditions. First, the weight loss, compared with what it would have been without the intervention, must be maintained for life. Second, at least 1 kg of weight is lost and this weight difference is maintained for life (that is, the person's lifetime weight trajectory is lowered by at least 1 kg). A 24-week programme costing £200 or less was estimated to be cost effective under the same conditions. However, there were not enough data to populate the model for adults with an initial body mass index (BMI) of more than 40 kg/m². So it was unclear whether or not it would be cost effective for this group. For programmes costing £500 per head to be cost effective, it is estimated that an average 2 kg weight differential must be maintained for life. A 3 kg loss must be maintained for life for programmes costing £1000 or more per head. The model estimated that programmes costing £100 or more per head are not cost effective if, on average, participants regain the weight lost within 2 to 3 years or less. This is regardless of the average initial weight loss. The key variable is thus the speed with which weight is regained. However, the PDG noted that evidence based on long term follow up of participants was limited.

The length of time that someone's weight trajectory must be below the 'without-intervention' trajectory and still remain cost effective is reduced by the following 4 factors:

• a higher initial weight loss

• the person being older (for a given BMI group)

• the person having a higher BMI (for a given age group)

• a lower cost per head of the intervention.

In relation to age, the model implies that the recommendations will generate better value for money for people older than 50 – even if they only maintain a lower weight trajectory for 3 to 10 years. This is because older people will gain the health benefits sooner (not because older people lose more weight than younger people). Trials suggest average weight loss is similar for all ages and BMI groups. For people aged 20–39, weight loss may need to be maintained for up to 40 years before the intervention is worth undertaking.

In relation to weight, the model implies that implementation of the recommendations will generate better value for money when used with adults who are obese (rather than overweight) (see adults who are overweight or obese). As a result, the PDG felt that people with a BMI between 30 and 40 kg/m² should be made a priority for funded referrals to lifestyle weight management programmes. But members also agreed that people who are overweight (BMI 25 to 30 kg/m²) should not be excluded from funded referrals if there is enough capacity. There were insufficient data to make a judgement on this for people whose BMI is above 40 kg/m².

The modelling data relate to population cohorts of a given age, sex and BMI category – not to every individual in each cohort, because weight loss and gain vary greatly between people in each cohort. Effective interventions for a particular cohort will usually be cost effective for people who have lost at least the average amount of weight, or who have regained weight at an average or slower than average rate.