Many people don't get enough fiber. Two dietitians, Lauri Wright and Samantha Coogan, say the exact time matters less than getting enough fiber over the whole day. Wright stresses total intake, while Coogan suggests splitting fiber across several meals.
A study in the British Journal of Nutrition compared higher-fiber and higher-protein diets in 19 adults who were overweight. Nearly half of each day's calories were eaten at breakfast. Stool samples showed a greater share of several beneficial bacteria on the higher-fiber diet. Both diets used the same meal schedule, so this does not show that fiber works better at breakfast than later.
If you're increasing your fiber intake from scratch, eating a lot of it in one sitting may feel uncomfortable, with gas or bloating in some people, Coogan said.
Instead of trying to front-load most of the recommended 25 to 30 grams of fiber at once, Coogan said it's ideal to split that intake into 7 to 10 grams per meal across several meals. She said this should be gentler on your stomach while still getting you the fiber you need.
Breakfast is an easy meal to fit fiber into, especially if you already enjoy foods like oatmeal, cereal, or other whole grains.
"Fill half your plate with vegetables or fruit at lunch and dinner, or swap white rice or pasta for brown rice, quinoa, or whole-grain pasta," Wright said.
At the end of the day, both dietitians agreed that the goal is just to get more fiber into your diet, however you can.