Staying upright after eating is one of the simplest, most consistently recommended reflux habits, and the reasoning is mostly gravity: an upright position keeps stomach contents lower, making it harder for them to travel back up into the esophagus compared to sitting hunched over or lying down.
Why walking specifically may add a benefit
A light walk after a meal may also help speed stomach emptying, which reduces the amount of time food sits in the stomach putting pressure on the lower esophageal sphincter. The operative word is light — a gentle walk, not vigorous exercise, since intense activity right after eating can itself trigger reflux in some people by increasing abdominal pressure.
How long and how soon
A ten to fifteen minute walk starting shortly after finishing a meal is a reasonable target; even standing and doing light activity around the house accomplishes the main goal if a walk outside isn't practical. The bigger point is simply avoiding the couch or bed for the first hour or so after eating, especially after the largest meal of the day.
This is one of the lowest-effort, most evidence-backed habits available and costs nothing to try.
