Does seeing a dietitian help with weight? A review of 62 trials

Why this study matters

Dietitians are regulated health professionals in Canada, and many people wonder whether working with one makes a measurable difference. This review, from the Evidence Analysis Center of the Academy of Nutrition and Dietetics, gathered every randomized trial it could find in which a dietitian delivered a weight-management program. It asked what happened to weight and several health measures compared with usual care or no program at all.

Who was in the study

The review included 62 randomized controlled trials of adults with overweight or obesity. The published summary does not give the total number of participants. The researchers searched six medical databases for trials published in English between January 2008 and January 2021.

What the researchers did

This was a systematic review and meta-analysis. A systematic review searches for all relevant studies using a set method. A meta-analysis combines their results into a single estimate.

The trials compared a weight-management program delivered by a registered dietitian, or the international equivalent, with usual care or no intervention. The researchers combined the results using a random-effects model, a statistical approach that allows for differences between trials. They checked for publication bias, which happens when studies with positive results are more likely to be published. They rated each trial's risk of bias and graded how certain the overall evidence was. Subgroup analyses looked at program features such as telehealth or group contacts.

What they found

Compared with control conditions, dietitian-led programs improved every measure below (R32-C141). Each result is a mean difference, which is the average gap between the dietitian group and the comparison group. The confidence interval is the range within which the true value would likely fall.

BMI is weight in kilograms divided by height in metres squared. The SF-36 is a survey that scores physical and mental well-being. "High certainty" means the researchers were confident the true effect is close to the estimate. "Low certainty" means the true effect could differ meaningfully.

The minus signs mean the dietitian groups had lower values than the comparison groups, which is the desired direction for weight, BMI, waist size and blood pressure.

Side effects and people who stopped

The published summary we reviewed does not report side effects or how many people dropped out of the trials.

What this study does not tell you

• The 62 trials used different programs, contact schedules and follow-up lengths. The averages hide a lot of variation.
• The comparison was usual care or nothing. The review does not measure what a dietitian adds on top of a specific weight-loss medicine.
• The 4.01% figure cannot be placed beside percentages from medicine trials. Different people, comparison groups and time frames were involved.
• Only English-language trials from 2008 to 2021 were included.
• The summary does not state how long the benefits lasted after programs ended.
• The summary we reviewed does not state who funded the review.

What it means in Canada

This review supports dietitian-led care as a measurable part of weight management, separate from any medicine. Many Canadians can access dietitians through provincial health services, employer benefits, or private practice. To find nutrition and lifestyle services, see compare services. For medicine information, see semaglutide in Canada and tirzepatide in Canada. For coverage, see public drug coverage by province.

Related reading

Other studies in this library that bear on the same question.

Source