"Stepping on the scales every day could be the key to weight loss, a study has found," the Mail Online reports. This report was based on a US study which suggested daily weighing can lead to a small, though sustainable, loss in weight.
The study involved 162 overweight and obese adults trying to lose weight, who were allocated to either weighing themselves daily and tracking their weight on a graph, or a control group. Both groups were given an educational session about other evidence-based strategies they could use to lose weight.
After a year, those weighing themselves lost more weight – about two kilos more on average – than those who didn’t. This difference seen in the averages between the two groups seemed largely to be due to an effect in men. The results in women in both of the groups were similar.
There are limitations to this study. For example, participants in the weighing group may have felt more pressure to lose weight than the control group as they were receiving the intervention.
Also, the fact that the weight loss was mainly found in a small group of men (just 40) is a preliminary finding, and needs to be confirmed in a larger sample.
Weight monitoring is already a part of many weight loss strategies. For some people, weighing themselves regularly may not be helpful and could actually be discouraging. Different people often find different ways to motivate themselves and a one-size fits all solution may not be effective.
Where did the story come from?
The study was carried out by researchers from the University of Minnesota and Cornell University in the US. No specific funding for the study itself was reported, but the first author was funded by a National Institutes of Health/National Institute of Diabetes and Digestive and Kidney Diseases-Ruth L. Kirschstein National Research Service Award.
The Mail Online’s story incorrectly reports the amount of weight lost in the study. It says that “Eventually, each participant lost a total of 10 per cent of their body weight.” While losing 10% of weight was the target for those taking part, only about 9% of those who weighed themselves and 5% of the control group achieved this. On average they only lost 2.5% of their weight.
What kind of research was this?
This was a randomised controlled trial (RCT) which looked at whether daily weighing and recording weight helped overweight adults to lose weight and keep it off.
Many trials have tested weighing yourself combined with other activities aimed at weight loss, but the researchers in this study wanted to look at the effect of just weighing yourself. They report that previous studies have had conflicting findings about whether weighing yourself helps you to lose weight, and many of the studies have been observational, meaning drawing conclusions about its effects is difficult.
An RCT is the best way to identify the effects of a particular intervention or treatment.
What did the research involve?
The researchers recruited 162 overweight or obese adults and allocated them at random to either weighing themselves daily or not doing this. After a year, the non-weighing group also started weighing themselves daily. The researchers compared how much weight each group lost in the first year, and whether they kept the weight off in the second year.
The researchers recruited participants through advertisements asking for volunteers who wanted to lose weight. Only adults aged 18 or over, who had a body mass index (BMI) of 27 or more, who did not have diabetes, and had never had an eating disorder were eligible to take part.
All participants had an educational session about evidence-based ways to lose weight, and a target of 10% reduction in weight over the year was recommended. These sessions emphasised that people should chose a weight loss strategy to suit their own needs. They also encouraged small changes to reduce intake by about 100 kilocalories a day, such as:
- skipping dessert a few times per week
- using a meal replacement for lunch three times a week
- abstaining from snacking most days of the week
At the end of the sessions for people in the self-weighing group, the intervention was explained to them. The researchers called their weighing intervention the "Caloric Titration Method" (CTM). They gave each member of the group a standard bathroom weighing scale and asked them to weigh themselves at the same time and way every day. Ideally, they were asked to do this first thing in the morning immediately after getting up. They were also asked to enter their weight on a website each day. (The site is still, at time of writing, accepting free registrations for people who want to try CTM.)
The website plotted a graph of weight to show whether it was changing, and also highlight the next weight loss target on the graph. The targets were each set at 1% of body weight, and once a target was achieved and the person stayed at this weight for eight days, the next target was set at 1% lower, and so on. This continued up to a maximum of 10% weight loss, after which they were asked to maintain the weight loss. If the participants did not enter at least three weights a week, they were sent an email reminder. In the second year, the group were asked to continue to use self-weighing to maintain their weight loss or lose more weight if they wished.
The idea is to allow people to see the effect of small changes to diet through weighing themselves, to see quickly whether the changes are working or whether they need to make more changes. The method promotes slow weight loss with the idea that this might be maintained better than rapid weight loss.
The control (no weighing) group were not asked to weigh themselves, but were told they would receive the intervention after a year. After a year they were given the scales and a session on CTM.
The researchers weighed participants four times during the study, and compared weight changes between the groups.
What were the basic results?
The participants were aged about 46 years old on average, and had an average BMI of 33.5 and average weight of 93.8kg. Most of the participants were female (82%), and of white ethnicity (89%).
The researchers found that over the first year, those who were weighing themselves daily lost significantly more weight than those who were not. People in the self-weighing group who completed the year lost an average of 2.6kg while the non-weighing group lost an average of 0.5kg. The results were similar if the last measurement available for people who did not complete the year were included in the analysis.
When looking at the results by gender, women in the two groups did not differ very much in their weight loss, but men who weighed themselves lost more weight than those who didn’t. However, this difference did not reach statistical significance, probably due to the small number of men in the study.
In the second year of the study, the weighing group kept off the weight they had lost (average change in weight 0.1kg). Once the control group started weighing themselves daily in the second year, they also lost 1.9kg on average.
Most of the participants did not reach their target 10% weight loss; on average they lost 2.5%.
How did the researchers interpret the results?
The researchers concluded that "the use of frequent weighing accompanied by visual feedback of weight, without a prescribed diet or exercise plan, was effective in producing a small but sustainable weight loss in overweight males". They suggest this strategy may be useful when combined with other approaches to achieve healthy weight loss.
This RCT suggested that weighing yourself daily and tracking your weight on a graph might help some people to lose weight.
The strength of this study was its RCT design, but there are some limitations:
- Participants could not be blinded to what intervention they were receiving, and this might have affected their attempts to lose weight. Those in the weighing group may have felt more pressure to lose weight than the control group as they were receiving the intervention, rather than the weighing having an effect itself.
- While the difference between the groups appeared to be due to an effect in men only, the study only included a small number of men (40) and results need to be confirmed in a larger sample.
- Participants were all volunteers who wanted to lose weight, and may be more motivated to do so than people in the general population.
- Most participants were adults of white ethnicity and results may not be representative of other groups.
- The average amount of weight lost was relatively small – 2.6kg or 5.7lbs over a year. As the authors suggest, it may need to be combined with other techniques to improve these results.
Overall, these results suggest that weighing yourself and keeping track of your progress on a chart might be useful, possibly more so for men. Weight monitoring is already a part of many weight loss strategies. NICE guidance recommends that lifestyle weight management services should include monitoring weight and participants' personal goals throughout these programmes. What helps people to lose weight may differ for each person, and the main thing is to find something that works for you.
The average effects seen in this study were relatively small so daily weighing is likely to need to be combined with other approaches to a calorie controlled diet and regular exercise to achieving greater weight loss. For more information join up with the NHS weight loss plan