Oats

If lentils are the savory answer to GLP-1 constipation, oats are the breakfast one. Oats are among the richest common sources of beta-glucan, a soluble fiber that forms a soft gel in the gut, eases the sluggish digestion these medications cause, and feeds a satisfying, slow-burning fullness. Dry rolled oats carry roughly 11 grams of fiber and a surprising 17 grams of protein per 100 grams, though a realistic 40-gram bowl lands closer to 4–5 grams of protein and 150 calories — which is exactly why the dietitian move is to fortify them. Stir in a scoop of protein powder, a spoon of Greek yogurt, or a tablespoon of nut butter and a plain bowl of oats becomes a balanced, protein-and-fiber meal that checks two of our six boxes at once. Served warm and soft, oats are gentle and soothing, in the same easy-to-tolerate camp as yogurt and broth, and overnight oats offer a no-cook, grab-from-the-fridge version for low-energy mornings. They also carry useful iron and magnesium, minor wins against the micronutrient erosion that comes with eating less. The main caveat is portion discipline in the other direction: oats are carbohydrate-dense, so a giant bowl can crowd out the protein you need or spike blood sugar if loaded with sweeteners — keep the base modest and let the protein topping do the heavy lifting. Choose rolled or steel-cut over instant flavored packets, which often hide added sugar. Compared with berries, the other fiber pick lower on this list, oats bring far more soluble fiber and staying power, making them the more strategic everyday choice for regularity.