Gaps in the evidence

Guidance

The Programme Development Group (PDG) identified a number of gaps in the evidence related to the programmes under examination, based on an assessment of the evidence. These gaps are set out below.

1. There is a lack of long-term (that is, 3 years or longer) trials of lifestyle weight management programmes to determine cost effectiveness.

(Source: evidence reviews 1a and 1c; economic modelling)

2. There is a lack of trials directly comparing lifestyle weight management programmes in the UK.

(Source: evidence reviews 1a, 1b and 1c)

3. There is a lack of evidence on whether there are any adverse or unintended effects associated with long-term weight management programmes. There is also a lack of evidence on 'weight cycling' (repeated attempts to lose weight) in relation to these programmes.

(Source: evidence reviews 1a, 1b and 1c; expert paper 1)

4. There is a general lack of evidence on which specific components of a lifestyle weight management programme ensure effectiveness. In particular, it is unclear what effect programme length and intensity has on effectiveness.

(Source: evidence reviews 1a and 1b)

5. There is a lack of evidence on the effect of sexual orientation, disability, religion, place of residence, occupation, education, socioeconomic position or social capital on the effectiveness of lifestyle weight management programmes. There is also a lack of analysis of participants by age and gender.

(Source: evidence review 1a)

6. The existing evidence base is limited by studies characterised by: short-term follow up, small sample sizes, the collection of data at only a limited number of time points (usually 2), demographic samples that limit the ability to generalise and non-reporting of reasons for people dropping out.

(Source: evidence reviews 1a and 1b)

7. There is a lack of evidence on whether any particular approach to commissioning leads to better outcomes for participants in lifestyle weight management programmes.

(Source: evidence review 2)

8. There is a lack of evidence as to whether any particular type of training for practitioners leads to more effective programmes.

(Source: evidence review 2)

The Committee made 5 recommendations for research into areas that it believes will be a priority for developing future guidance.