The Faculty of Medicine at the University of Southampton conducted a study to identify whether tailored dietary advice is superior to usual dietetic advice in promoting a reduction in waist circumference, weight loss, body fat and favourable changes in metabolism in individuals with overweight and obesity.
We interviewed Dr Ella Baker, research fellow, and Dr Louise Clamp, research dietician, who have been carrying out the study to learn more about the study and find out about first conclusions.
How was the study designed?
The main goal of the trial was to investigate the effect of providing a personalised nutrition plan to individuals with overweight or obesity over a 4-month period. We were mainly interested in decreasing waist circumference, body weight loss and fat mass loss, but also in improving metabolic and inflammatory markers measured in the bloodstream.
Our trial had three groups of participants. All participants received an individualised eating plan, but two groups received additional information and education based on their metabolic, inflammatory and genetic phenotype (which we described as a “cluster”). The information these two groups received was orientated towards foods that would target improvements according to the cluster. The difference between these two groups was that one also received behaviour change prompts, encouraging the participants to adopt healthy behaviours. We had consultations with all participants during the trial and they made visits to our clinical research facility at the start and end of the study so we could measure their body composition and take blood samples.
How many people are participating in the study, and which requirements have to meet?
We recruited men and women aged 18-65 years with excess body weight, but who were otherwise generally healthy. We ended up with 60 participants starting the 4-month intervention and of these, 54 participants completed the study. These participants were randomly assigned to the three groups (control (n=15) or personalised nutrition (n=19) or personalised with behaviour change prompts (n=20)).
The study lasts four months. What was expected from volunteers during the study period?
Before starting the intervention, all participants came to our clinical research facility. During their visit we measured their body weight, body fat and waist and hip circumference and they provided samples of blood, urine, faeces and saliva. The participants also completed several questionnaires, for example, about their consumption of different foods and how much physical activity they did and also about their quality of life.
During the 4-month period of the trial, participants tried to incorporate the dietary changes they were recommended. All participants were followed up monthly. They received detailed advice based on their feedback and were orientated towards implementing three targeted improvements over the coming month. The PREVENTOMICS analysis provided a basis for more personalised dietary changes. For example, individuals in the microbiota cluster were encouraged to incorporate at least one new pro- and pre-biotic food each month. Obviously, the participants in the behaviour change group received prompts via their smartphone, encouraging them to incorporate healthy activities into their daily routine.
At the end of the 4-month intervention, the participants returned to the clinical research facility and we repeated all the measurements and questionnaires we had done at the earlier visits. From the nutrition questionnaires we were able to determine how the food intake pattern had changed in response to the advice received. In general, we have seen broad shifts away from refined carbohydrates, sources of added sugar and processed meat and increases in fruit and vegetable intake, which resulted in an improvement in the inflammatory nature of the diet, particularly among the personalised diet groups.
We have seen broad shifts away from refined carbohydrates, sources of added sugar and processed meat, resulting in an improvement in the inflammatory nature of the diet
Which indicators did you use to assess the impact of the nutritional study in participants’ health?
We were mainly interested in whether participants had reduced waist circumference (primary outcome measure), but also whether they had lost body fat and body weight and whether that differed between the groups.
It appears that the more personalised information and education provided to the experimental groups may have increased their adherence to the diet plan compared to the control group. However, it will be interesting to see how blood biomarkers, associated with specific clusters, have changed in response to more targeted food recommendations in the personalized diet groups. (e.g. metabolic and inflammatory markers in the blood and the gut microbiota). It will also be of interest to quantify the dietary improvements and assess changes in quality of life.
Personalised information seems to have increased participants’ adherence to the diet plan
Could you prove that participants following PREVENTOMICS tailored nutritional advice experienced a greater reduction in excess body fat and improved their overall health?
We found that the group receiving personalised advice and heathy behaviour prompts had a reduction in their waist circumference by an average of 5 cm. This was a bigger reduction than seen in the control group and would suggest a loss of fat from within the abdomen. That is an important improvement.
That group also tended to show improvements in body weight and body fatness. Thus, it seems that the tailored nutritional advice combined with healthy behaviour prompts is effective in this population. It remains to be seen whether any of the interventions improved metabolism or inflammation. We should have those results soon.