Digestive changes — especially constipation — are common in the first weeks of keto (research review). The good news: it's usually easy to fix.

Why it happens

  • Less fiber. Cutting grains, beans, and fruit often means eating less fiber, which keeps things moving.
  • Fluid and salt shifts. Early keto flushes out water and sodium, which can leave the gut drier.
  • Diet change itself. Any big shift in how you eat can briefly upset digestion while your body adapts.

How to fix it

  • Eat more low-carb fiber. Non-starchy vegetables, nuts, seeds (chia and flax are great), and avocado. The research review suggests around 15–20 g of fiber a day from these foods (review).
  • Drink more water. Fiber works best with enough fluid.
  • Keep salt and electrolytes up. See electrolytes on keto. Magnesium in particular can help.
  • Move your body. Even a daily walk helps digestion.

When to see a doctor

Most keto constipation eases within a couple of weeks as your body adjusts. See a doctor if it's severe, lasts a long time, or comes with pain, bleeding, or other worrying symptoms — those need proper medical attention, not diet tweaks.

Sources