5:2 diet advice as effective as GP weight management advice

5:2 diet advice as effective as GP weight management advice
© iStock/Edwin Tan

A clinical trial has found people prefer receiving information on the 5:2 diet than standard GP advice on weight management despite both interventions achieving similar weight loss results.

A new trial funded by the Medical Research Council (MCR) and led by the Queen Mary University of London is the first randomised evaluation of the 5:2 diet, a popular type of intermittent fasting. Researchers studied the long-term effects of 5:2 diet instructions compared to traditional weight management advice in 300 UK adults with obesity over a year.

The 5:2 diet follows the guidelines that individuals can eat what they want five days a week, then dramatically cut calories for the other two days.  Dieters are recommended to consume a ‘normal’ number of calories five days a week, and for the other two days, they are asked to eat 25% of their usual calorie total – 500 calories for women and 600 for men.

The first randomised study of the 5:2 diet

In the study, a 20-minute traditional weight management advice session involves the programme and key tips with an advisor then supporting material is supplied. This includes the British Heart Foundation guides ‘Facts Not Fads’ and ‘Get Active, Stay Active’, the NHS ‘Change 4 Life’ series of booklets and a leaflet listing local resources for exercise. However, participants in the 5:2 group received a leaflet on restricting their caloric intake on two non-consecutive days a week, with meal examples with the required calories and pointers to additional online support.

Previous evidence suggests that peer support could be important for encouraging dieters to adhere to and realise the effects of the 5:2 diet. To test this, the researchers studied the impact of a weekly support group in addition to the simple 5:2 diet advice. They also found that initial face to face support generated better early effects and improved adherence to the 5:2 diet; these effects weakened over time.

The effects of weight management advice

The study found that long-term weight loss was similar for those who received the 5:2 diet or standard GP weight management advice, with 18% and 15% of participants on average losing at least 5% of their body weight at the one-year mark. However, when asked to rate each intervention, participants in the 5:2 diet group were more likely to recommend the intervention to others or are willing to continue with their diet.

Dr Katie Myers Smith, Chartered Health Psychologist and Senior Research Fellow at Queen Mary, said: “Here we’ve been able to provide the first results on the effectiveness of simple 5:2 diet advice in a real-life setting. 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. Based on these findings, GPs may consider recommending the 5:2 diet as part of their standard weight management advice.”


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