What it is
Fiber is the part of plant carbohydrates your own enzymes can't break down. Your gut bacteria ferment some of it; the rest provides bulk. Between them: better satiety per calorie, steadier digestion, healthier blood lipids, and a long list of associations with good long-term outcomes.
How much
The common guideline is about 14 g per 1000 kcal — roughly 25 g for most women and 38 g for most men. Your automatic goal applies that logic, scaled to your calorie target, as a floor: fiber is a nutrient to reach, not to cap. Increase it gradually — a sudden jump is the classic recipe for bloating.
How well it's tracked
Well. Fiber is on virtually every nutrition label and is stored with every diary entry, so your fiber trend is one of the trustworthy ones.
Too little
Low fiber shows up as hunger between meals, sluggish digestion, and a diet that's easy to overeat. It's the most common shortfall in modern diets — most people run well under the guideline.
Food sources
Legumes, oats, whole grains, fruit (especially with skins), vegetables, nuts, and seeds. As a rule: the closer a carb is to how it grew, the more fiber came along.
In the app
Fiber has its own card in Insights with a chart against your goal band, top contributors per day, and a floor/target you can customize.