I was told by my gastroenterologist that I have Chronic Constipation and to eat 26 grams of fiber per day. Also, to stop eating oily foods and salt and drink at least 8 - 10 8oz glasses of water per day. Because I eat so much fiber, I end up drinking close to a gallon of water per day. Because of all the water I also drink Propel, an electrolyte drink, so I don't loose all the salt in my body. (Some of the food I eat has added salt.) I also drink one Boost high protein beverage per day in order to add to my vitamin, mineral and protein intake.
I saw a dietitian who only gave me a 1 day diet. I recommend that you see one, if you can afford it. I found high fiber products in the grocery store and the Boost, so the diet has been modified.
I'm only allowed to have 1 Tablespoon oil & Vinegar and 1 Tablespoon Avocado Oil per day.
Try eating 1 piece of Keto bread: 9 grams of fiber, 2/3 cup of Fiber One Cereal: 18 grams of fiber
or 2 Tablespoons Chia Seeds mixed in 4 oz Activia: 8 grams of fiber (mix well and leave overnight in the refrigerator, 1 cup berries: 7 grams fiber, 1 medium apple: 4 grams of fiber, 4 - 5 prunes: 3 grams fiber, 2 Tablespoons popcorn - (I pop it in the microwave without oil): 3 grams fiber, 1 medium sweet potato: 4 grams fiber, and 2 Tablespoons soy beans: 7 grams fiber
Mix and match to suit your taste. Always check the fiber content on the foods you buy, because sometimes the amount of fiber I'm listing here doesn't match the products in the grocery store.
You also have to keep in mind that you can eat all the vegetables you want and be sure to eat enough protein.
You may not need to eat as much fiber, so start with a much smaller amount of fiber and a lot of water. You don't want to end up with diarrhea.
I hope this helps you.