In the last decade, the ‘5:2 diet’ has exploded in popularity, transforming the eating patterns of thousands of people seeking to lose weight.
The 5:2 diet is an example of what’s called intermittent fasting, or time-restricted eating.
At its most basic, the 5:2 system means you can eat what you want five days per week (trying to still eat sensibly on those days), while on the other two days of the week, you restrict your calorie intake significantly, often to around just 500 calories.
While some research suggests intermittent fasting is no better than conventional dieting for long-term weight loss, other kinds of experiments hint at significant benefits linked to time-restricted eating – including health benefits from fasting that might go well beyond dieting.
Now, a new study led by researchers from Queen Mary University of London in the UK has identified another reason why some people may want to consider the 5:2 diet over other approaches.
In what the researchers claim is the “first randomized evaluation of the 5:2 diet”, the team studied 300 adults with obesity, each of whom were randomly assigned to one of three different kinds of weight loss intervention.
In the experiment, 100 of the participants (one-third of the whole group) were given conventional weight management advice in a single session with an advisor, who provided written materials that explained things like portion control, keeping a food diary, and tips on how to avoid unnecessary snacks.
Another group of 100 participants (called the ‘self help’ group) had a different session, in which they were advised on how to follow the 5:2 diet during the experiment, and given a leaflet explaining meal examples, with links to additional online support, but were otherwise left to try the diet by themselves without much additional assistance.
The last 100 participants received similar advice and documentation about how to follow the 5:2 diet, but were additionally enrolled in a series of group support sessions that ran for six weeks, aimed at helping them discuss their experiences on the diet with others, ask questions of advisors, and so on.
These three groups of participants were then followed for one year, at which point the experiment ended. At the end of the year, each of the three groups showed signs of moderate weight loss on average: 15 percent of participants in the ‘conventional advice’ group lost at least 5 percent of their body weight (the primary outcome measure of the study).
The two groups of 5:2 dieters lost slightly more weight on average in terms of that measure, with 18 percent of the ‘self help’ group losing at least 5 percent of their body weight, compared to 28 percent of the ‘group support’ participants.
But while all groups achieved moderate weight loss during the experiment, there was another key differentiator in the data.
When compared against the participants who received conventional weight management advice, the 5:2 diet participants rated their experience during the experiment more highly.
In a survey about the experiment, the 5:2 dieters rated their interventions higher in terms of helpfulness than the conventional weight management advice, and indicated they were more likely to recommend the diet to others.
Feedback also showed the 5:2 dieters had more readiness to continue the diet after the experiment ended.
In short, you might say the 5:2 dieters seemed to have an overall better time while trying to adhere to their weight loss plan.
“Here we’ve been able to provide the first results on the effectiveness of simple 5:2 diet advice in a real-life setting,” explains health psychologist Katie Myers Smith from Queen Mary University of London.
“We found that although the 5:2 diet wasn’t superior to traditional approaches in terms of weight loss, users preferred this approach as it was simpler and more attractive.”
According to the researchers, the weight loss efficacy of 5:2 seen in the study is about the same as what other intermittent fasting studies have shown.
While 5:2 dieting doesn’t seem to achieve amazing results compared to conventional weight management advice, the more favorable user ratings could be an important factor to consider for doctors advising real-world people struggling to lose weight.
“Clinicians providing brief advice on weight management may consider recommending the 5:2 diet,” the researchers conclude in their study.
“The approach is not superior to the standard multimodal advice, but it is simpler and more attractive to users.”
The findings are reported in PLOS One.