Twenty-five out of 28. That is the number to put in your next corporate proposal, and it is not about what happens during coaching. It is about what happens after it ends.

A rapid systematic review published in the American Journal of Lifestyle Medicine went looking for one specific thing: whether health and wellness coaching clients were still better off once the coach went away. The authors screened 231 studies from the Compendium of Health and Wellness Coaching and selected 28 of sufficient quality to examine whether a coaching effect survived post-intervention.

Coaching effects were sustained in 25 of the 28 studies — nearly 90%.

The design detail that makes this usable

Most coaching "evidence" measures people while they are still being coached. This review deliberately did not.

Clients had to receive no additional coaching before the follow-up measurements, which usually occurred three to 12 months after the original coaching period. The average engagement across the 28 studies ran 6.4 months with about eight sessions, and follow-up measures came, on average, nearly seven months after coaching ended.

Translated: roughly eight sessions over half a year, then half a year of nothing, then someone knocked on the door to check.

And in nine of the studies, things had not merely held. Outcomes of interest actually improved after the coaching stopped. The Wellcoaches summary of the findings suggests habits formed during coaching kept compounding months after the final session.

Read the fine print before you quote it

The honest version of the number matters more than the loud version. The authors sorted outcomes into physiological, behavioural, psychological and health risk categories, rating each as not sustained, partially sustained, fully sustained or improved — and 25 of 28 studies showed partially or fully sustained or improved outcomes in one or more variables studied.

One or more variables. Not every measure in every trial. Three studies did not show it at all. The review also flagged limitations in the available research and the need for better-designed long-term studies.

Still, there is a genuine benchmark here. The authors' finding is backed up by a large JAMA-published cluster randomised trial in which blood pressure changes after coaching held for up to four years.

Why this ruins the standard renewal pitch

Here is the uncomfortable part for anyone selling length. A meta-analysis of randomised controlled trials in Academy of Management Learning & Education put coaching's effect size at g = .59 — solidly moderate — and found effects were larger with qualified coaches in non-leadership applications, while not depending much on the length of the overall coaching assignment.

More months is not the product. Durability is the product.

The field appears to be catching up to that. A cross-domain rapid systematic review titled "How Long Do Coaching Effects Last After the Engagement Ends?", covering studies that report follow-up assessment, was published 8 October 2026 in the International Journal of Evidence Based Coaching and Mentoring.

If you are writing a proposal this week, the defensible line is not "you will feel better in 12 weeks." It is: measure the client six months after we finish, and build the engagement so that measurement survives.