Wednesday October 31 2012
Gradual weight loss has better long-term results
“Weight maintenance is the key to dieting,” exclaims The Daily Telegraph, while The Independent entices readers in by headlining “how to end yo-yo weight loss”.
These headlines stem from a randomised controlled trial of 267 obese women that split the women into two groups:
- women who went into a 20-week weight loss programme, followed by an eight-week problem-solving training module – where they were given advice on ways to maintain their weight loss
- women who had the eight weeks ‘stability skills’ training before entering into the 20-week weight loss programme
The ‘stability skills’ training included practical advice and training on ‘simple, hassle-free’ ways to maintain weight, such as becoming more aware about portion size and gradually increasing levels of physical activity.
Both groups lost similar amounts of weight during the identical 20-week weight loss programmes – approximately 9% of their body weight (7.3-7.7kg (16-17lb) – but women who had the ‘stability skills’ training were able to keep more of their weight off.
After a year, those who first had the skills training regained an average of 1.45kg (3.2lb), compared with 3.3kg (7.3lb) regained by those who did not have the training.
The study strengths included a relatively large study size, a randomised design and year-long follow-up period. However, a limitation was that the majority of the study participants were middle-aged, white, university-educated women, so there is no guarantee the ‘stability skills’ element would work in other groups.
It may also be the case that the stability skills training may be just as effective if carried out after the weight loss programme and that the content of the training is more important than its timing.
The study authors acknowledged that they did not know whether the timing or the content of the skills training were responsible for the weight maintenance effects, or a whether it was a combination of both.
Where did the story come from?
The study was carried out by researchers from Stanford University School of Medicine and the University of Florida and was funded by the US National Institutes of Health.
The study was published in the peer-reviewed Journal of Consulting and Clinical Psychology.
The media reporting was generally accurate and explained how this study may provide an approach to help some women maintain weight loss achieved through adopting ‘stability skills’ to avoid ‘yo-yo’ weight loss.
What kind of research was this?
This was a randomised control trial (RCT) looking at whether learning a set of ‘stability skills’ before losing weight helped to keep the weight off.
The researchers highlight that many weight loss interventions produce short-term success, but the problem is keeping the weight off in the long term. Typically, some or all of the weight is put back on after the diet has finished, leading to so-called ‘yo-yo’ dieting and weight loss.
The researchers wanted to find out whether training women in maintaining their weight before a weight loss programme (through ‘stability skills’ training) would help them keep the weight off after the programme.
Or, as the Daily Mail, puts its: “Delay your diet for two months while you practise it first”.
What did the research involve?
A total of 267 overweight or obese women (having a BMI of 27-40) were recruited and randomly assigned to one of two six-month interventions. Their weight was assessed at the start (baseline) and again at six, 12 and 18 months.
The first group, known as the Maintenance First group, participated first in a newly designed eight-week stability skills maintenance module and then started a standard 20-week-long weight loss programme. The other group, Weight Loss First, was designed to represent the more mainstream approach. This group participated first in the 20-week weight loss programme and then started a different eight-week course on problem solving skills and maintenance. This did not contain the same new ‘stability skills’ package as the first group.
The stability skills maintenance module aimed to teach the women a set of skills designed to optimise day-to-day satisfaction with their lifestyle and teach self-regulatory habits to maintain their weight. This involved teaching them about:
- energy balance principles
- appropriate portion sizes and being physically active without feeling deprived or dissatisfied
- daily weighing to monitor fluctuations in weight but without feeling guilty or alarmed
- fine tuning lifestyle habits by making quick, small, easy adjustments with minimal effort
- how to overcome inevitable setbacks with confidence
(Similar advice can be found in our series of Lose Weight articles).
The 20-week weight loss programme that both groups received was multifaceted but, in brief, contained weekly facilitated group sessions where participants were weighed, goals were set and reviewed.
This kind of programme is widely used by commercial slimming clubs.
Participants were also given written materials containing strategies on how to change their behaviour, plan social support and prevent relapse. A key part of this programme was effective problem solving within the group eg generating solutions to problems for one another.
The interventions lasted a total of six months, after which the participants were followed up for another 12 months to assess their weight.
There was no staff contact during the follow-up period, so the women were left to their own devices.
This was to mimic ‘real-world’ conditions where a woman would exit a commercial weight loss programme and not receive any long-term support.
The six-month weight loss programme deliberately ended in October so that the 12-month maintenance phase included Halloween (traditionally more of a celebration in the US than in the UK) through to New Year’s Eve to challenge the women in maintaining their weight loss efforts.
Only women over the age of 21 who were free of diseases such as diabetes, heart disease and other chronic conditions – as well as being able to be physically active – were eligible for inclusion in the study. Pregnant women were excluded.
The analysis was based on the intention to treat principle, which analyses participants in the groups to which they were originally assigned. This includes people who dropped out of the study for any reason.
What were the basic results?
Retention in the trial was very high, with 93.3% of women initially randomised also being weighed at 18 months.
A total of 267 women were analysed. The average age of the women in both groups was 48-49 years old and over two thirds were college-educated and white. Most women had participated in a weight loss programme in the past.
The Maintenance First participants lost a similar amount of weight during the six-month intervention period (average % weight loss -8.6%, standard deviation [SD] 5.7%) as the Weight Loss First participants (average weight loss -9.1%, SD 6.9%).
This equated to an average 7.3kg (16.1lb) (SD 4.9kg or 10.9lb) weight loss in the Maintenance First participants compared to 7.75 kg (17.1lb) (SD 6.1kg or 13.4lb) in the Weight Loss First participants.
However, Maintenance First participants regained significantly less weight during the 12-month follow-up period than the Weight Loss First group.
The average weight regained in the Maintenance First group was 1.45kg (3.2lb) – which equated to regaining 20% of their lost weight, compared to 3.3kg (7. lb) for Weight Loss First participants, who regained 43% of their lost weight.
This difference held even after the researchers adjusted for small differences in starting weight and other demographic characteristics.
During the stability phase the majority of Maintenance First participants kept their weight within 5lb less than their starting weight.
How did the researchers interpret the results?
The researchers concluded that learning stability skills before losing weight was successful in helping women to maintain weight loss without intervention staff contact during the follow-up. They suggest this approach could inform the study design of future weight loss interventions.
This RCT involving 267 obese, white, college-educated women showed that training women for eight weeks in techniques to stabilise their weight before entering into a comprehensive weight loss programme can help them keep more weight off than women who went straight into the weight loss programme. All women regained some weight but it was significantly less in those receiving the training.
The study had many strengths, including its relatively large study size, its randomised design and year-long follow-up. However, it has limitations that should also be considered.
Two thirds of the study sample were middle-aged, white, university-educated women. There is no guarantee this type of intervention would work in other groups, as education level and ethnicity are known to influence obesity levels at a population level.
The authors acknowledge that future research needs to examine whether the stability skills-first approach works for other groups, such as:
- younger women
- men of all ages
- individuals who are less educated
- individuals from different ethnic backgrounds
- people who are heavier (eg morbidly obese people)
- those who have other (co-morbid) medical conditions
- those with a binge eating disorder
Also, while a 12-month follow-up period is a relatively long time as far as RCTs go, this is not a long time in the grand scheme of a woman’s life.
So, it is not clear whether all the women in the study will eventually put the weight back on, just at a slower rate. As the aim was to avoid ‘yo-yo’ weight changes, this is important. Studies with longer follow-up times will be needed to clarify whether this is the case and whether the weight stays off or creeps back on.
It was not clear how important it was that the stability skills training came before the weight loss intervention because the Weight Loss First group did not receive the same stability skills training after. Hence, it may be the case that the stability skills training may be just as effective if placed after the weight loss and the content of the skills training is more important than when it is delivered. This limitation was acknowledged by the study authors.
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on twitter.