Paleo Diet Constipation: Causes, Fiber Math and Fixes

By Paleo Life Coach Editorial Team · Last updated October 12, 2026 · Checked against NIDDK, gastroenterology and dietetic guidelines, and USDA FoodData Central

You cut out bread, oatmeal and beans, filled the plate with meat and eggs, and a week later you’re running to the bathroom less often than you used to. Paleo diet constipation is a common complaint in forums, and it usually has a plain cause: the foods paleo removes are some of the biggest fiber sources in a typical diet. This guide counts fiber in two real paleo days using USDA data, lists the paleo foods with the most fiber per serving, and explains which fixes have trial evidence behind them.

The quick version: Paleo can cause constipation when grains and legumes are replaced mostly by meat and eggs, which contain no fiber. A meat-heavy paleo day can fall under 10 g of fiber; adults need 22-34 g. Adding berries, kiwifruit, avocado, vegetables, nuts and seeds, plus enough fluids, usually closes the gap.

Does the paleo diet cause constipation?

It can, but it doesn’t have to, and the only trial that reported bowel symptoms found the opposite problem. In a four-week randomized trial of 39 healthy women, 23% of the paleo group reported diarrhoea compared with 0% in the group following Australia’s standard dietary guidelines (Genoni et al., 2016). The study didn’t report constipation rates.

What does change on paleo is the type of fiber you eat. The same research group found that paleo removes “two major sources of fibre, grains and legumes,” and resistant starch intake fell significantly on the paleo diet (Genoni et al., 2019). Long-term paleo followers ate 2.62 g (strict paleo) and 1.26 g (pseudo-paleo) of resistant starch a day, compared with 4.48 g in controls, and had a different gut bacteria profile (Genoni et al., 2020).

So paleo isn’t a constipating diet by design. A paleo plate that’s mostly meat, eggs and a side salad is low in fiber, and low fiber is one of the causes of constipation the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) lists, alongside not drinking enough liquids, low physical activity and changes to how much and what you eat (NIDDK). Starting paleo checks the last box by definition.

How much fiber does a paleo day actually contain?

It depends almost entirely on what fills the space the bread used to fill. NIDDK says adults should get 22 to 34 grams of fiber a day, depending on age and sex (NIDDK). Here are two paleo days with the same protein foods, counted from USDA data.

Worked example: a meat-heavy paleo day vs a fiber-forward paleo day

Worked example: a meat-heavy paleo day vs a fiber-forward paleo day
Meal	Meat-heavy day	Fiber (g)	Fiber-forward day	Fiber (g)
Breakfast	3 eggs + 30 g bacon	0	3 eggs + 1 cup spinach + 1 cup raspberries	8.7
Lunch	150 g chicken breast + 2 cups romaine + olive oil	2.0	Same + half an avocado	8.7
Dinner	200 g sirloin + 1 cup broccoli	2.4	Same + medium baked sweet potato	6.2
Snack	1 oz almonds	3.5	2 kiwifruit + 1 oz almonds + 1 tbsp ground flaxseed	9.5
Total fiber		7.9 g		33.1 g

Calculated from USDA FoodData Central SR Legacy: egg 171287, bacon 168277, chicken breast 171077, romaine 169247, sirloin 168728, broccoli 170379, almonds 170567, spinach 168462, raspberries 167755, avocado 171705, baked sweet potato 168483 (114 g), green kiwifruit 168153 (69 g each), ground flaxseed 169414 (7 g). Portion weights from USDA household measures.

The meat-heavy day reaches only a third of the low end of the NIDDK range. The fiber-forward day reaches 33.1 g without a single grain or bean, and, after dropping the bacon, it adds only about 340 calories. Both days are low in total calories as written; add cooking fat or bigger portions to meet your needs, and the fiber totals won’t change.

If you also cut carbs hard, the gap gets wider, because many of the highest-fiber paleo foods are fruit and starchy vegetables. Our guide to paleo diet carbs per day shows how to keep carbs moderate without dropping fiber.

Which paleo foods are highest in fiber?

Berries, artichokes, chia and flax lead per serving. The second number column matters if you’re watching calories: it shows fiber per 100 calories, so you can see which foods give the most fiber for the energy they add.

Which paleo foods are highest in fiber?
Paleo food and portion	Fiber per portion (g)	Calories per portion	Fiber per 100 calories (g)
Chia seeds, 1 oz (28 g)	9.8	138	7.1
Raspberries, 1 cup (123 g)	8.0	64	12.5
Blackberries, 1 cup (144 g)	7.6	62	12.3
Prunes, about 10 (100 g)	7.1	240	3.0
Artichoke, 1 medium (128 g)	6.9	60	11.5
Avocado, half (100 g)	6.7	160	4.2
Pear, 1 medium (177 g)	5.5	112	4.9
Apple with skin, 1 medium (182 g)	4.4	95	4.6
Green kiwifruit, 2 (138 g)	4.1	84	4.9
Sweet potato, baked, medium (114 g)	3.8	103	3.7
Almonds, 1 oz (28 g)	3.5	164	2.2
Brussels sprouts, 1 cup raw (88 g)	3.3	38	8.8
Broccoli, 1 cup raw (91 g)	2.4	31	7.6
Cauliflower, 1 cup raw (107 g)	2.1	27	8.0
Flaxseed, ground, 1 tbsp (7 g)	1.9	37	5.1

Source: USDA FoodData Central SR Legacy, raw unless noted. Meat, poultry, fish, eggs and oils contain no fiber.

Two things stand out. Berries and green vegetables give the most fiber per calorie, so they’re the best fit if you’re eating paleo to lose weight. Prunes and nuts are fiber-dense per portion but calorie-dense too, which is fine in normal amounts. Our paleo diet food list shows where each of these sits in the paleo rules.

What do clinical guidelines say helps with constipation?

Two recent guidelines are worth knowing, and several of their food recommendations happen to be paleo.

The 2025 British Dietetic Association (BDA) guideline is the first full dietary guideline for chronic constipation in adults. Built from four systematic reviews covering 75 randomized trials, it made food recommendations for kiwifruit, prunes and rye bread, drink recommendations for high-mineral water, and supplement recommendations for fiber supplements, some probiotics, magnesium oxide and senna. It made no recommendation for any whole diet because the evidence was lacking (Dimidi et al., 2025). That includes paleo.

The 2023 American College of Gastroenterology and American Gastroenterological Association guideline covers over-the-counter and prescription treatments. It suggests fiber supplements such as psyllium, inulin or bran (a conditional recommendation, low certainty of evidence) and magnesium oxide (conditional, very low certainty), and strongly recommends polyethylene glycol (AGA summary).

Here’s how those recommendations line up with paleo:

What do clinical guidelines say helps with constipation?
Recommended option	Fits paleo?	Notes
Kiwifruit	Yes	2 green kiwifruit a day was the dose tested in a US trial
Prunes	Yes	100 g a day in the same trial; calorie-dense
Rye bread	No	A grain; skip on paleo
High-mineral water	Yes	Plain water with naturally high mineral content
Psyllium (fiber supplement)	Gray area	A seed husk, not a grain; many paleo followers use it
Bran or inulin supplements	Bran no; inulin depends on source	Bran comes from grains
Magnesium oxide, senna, laxatives	Not a food question	Ask your doctor or pharmacist before using them regularly

Sources: Dimidi et al., 2025; AGA summary of the 2023 ACG-AGA guideline; Chey et al., 2021.

Do kiwifruit and prunes work as well as fiber supplements?

In one US trial, they did about as well. Researchers at Michigan Medicine in Ann Arbor assigned 79 adults with chronic constipation to 2 green kiwifruit a day, 100 g of prunes a day, or 12 g of psyllium a day for four weeks (Chey et al., 2021). All three increased complete bowel movements per week. Kiwifruit and prunes improved stool consistency; all three reduced straining. Side effects were most common with psyllium and least common with kiwifruit, and fewer people were dissatisfied with kiwifruit than with the other two.

It was a small, partly randomized trial, and 87% of participants were women, so treat it as encouraging rather than settled. But it means the paleo-friendly options aren’t second-best choices: a couple of kiwifruit a day is a reasonable first step.

How do you fix constipation on paleo?

Work through these in order. Most people find the first three are enough.

Add fiber at every meal, a little at a time. NIDDK advises adding fiber gradually “so your body gets used to the change” (NIDDK). Add one item from the table above each day or two rather than jumping from 8 g to 33 g overnight.
Drink enough. NIDDK says liquids help fiber work better and that you should ask a health care professional how much is right for your size, activity and climate. Bone broth and soups count; our paleo soup recipes add vegetables and fluid at once.
Eat 2 kiwifruit or a portion of prunes daily. Both fit paleo and were tested in the trial above.
Don’t fear starchy vegetables. Sweet potatoes, squash and fruit add fiber that strict low-carb paleo cuts out.
Move. NIDDK lists low physical activity as a cause of constipation. Walking counts; see paleo exercise for how hunter-gatherer activity compares with ours.
Check your supplements and medicines. NIDDK lists iron supplements, calcium-containing antacids, opioid pain medicines and some blood pressure and antidepressant medicines among those that can make constipation worse. If you started a calcium or iron supplement when you dropped dairy or grains, mention it to your doctor.

If you’re eating paleo for the first time, there’s also an adjustment period. NIDDK notes that bowel habits can change when “you change how much and what you eat.” Other first-weeks symptoms are covered in our paleo flu guide.

When should you see a doctor about constipation?

See a doctor if constipation doesn’t improve with these changes, or if you have a family history of colon or rectal cancer. NIDDK says to see a doctor right away if constipation comes with any of these (NIDDK):

bleeding from the rectum or blood in your stool
constant pain in your abdomen
inability to pass gas, vomiting or fever
lower back pain
losing weight without trying

Don’t start regular laxative or magnesium supplement use without talking to your doctor or pharmacist, especially if you have kidney disease or take other medicines.

Frequently asked questions about paleo diet constipation

Why am I constipated on the paleo diet?

Most often because fiber dropped. Paleo removes grains and legumes, two major fiber sources, and meat, eggs and oils contain none. A meat-heavy paleo day can provide under 10 g of fiber against an adult target of 22-34 g. Fluid intake, activity and the general change in diet can also slow things down in the first weeks.

How long does constipation last when starting paleo?

There’s no study that measures it. NIDDK notes that changing how much and what you eat can change bowel habits, and most people adjust as they add fiber and fluids. If constipation lasts more than a couple of weeks after you’ve raised fiber, or comes with pain, blood or weight loss, see a doctor.

What paleo foods help you poop?

Kiwifruit and prunes have the best trial evidence: 2 green kiwifruit or 100 g of prunes a day improved bowel movements in a four-week US trial. Raspberries, blackberries, artichokes, chia seeds, avocado, pears and vegetables are also high in fiber. Drink enough liquid alongside them so the fiber works.

Is psyllium husk paleo?

It’s a gray area. Psyllium is the husk of a plant seed, not a grain or legume, so many paleo followers accept it, though strict lists rarely mention it. Fiber supplements such as psyllium carry a conditional recommendation for chronic constipation in the 2023 gastroenterology guideline. Start with a small amount and plenty of water.

Can paleo cause diarrhea instead?

Yes. In a four-week trial of 39 women, 23% on the paleo diet reported diarrhoea compared with none on a standard healthy diet. If diarrhoea lasts more than a few days or comes with fever or blood, talk to your doctor.

Do I need a fiber supplement on paleo?

Usually not, if you eat fruit, vegetables, nuts and seeds at most meals; the fiber-forward day above reaches 33 g from food alone. A supplement can help if you can’t reach your target with food. Ask your doctor before relying on supplements or laxatives regularly.

Your next step: count one day of fiber

Write down what you ate yesterday and add up the fiber using the table above. If you’re under 20 g, add one high-fiber food per meal over the next week, starting with kiwifruit or berries at breakfast, and drink a glass of water with each. For a full view of what paleo can leave short besides fiber, read our guide to paleo diet nutrient gaps.

Consider this general nutrition reading, not a replacement for advice from your doctor. Talk to your doctor if constipation is new, severe or lasting, or before using laxatives or supplements.

Paleo Diet Constipation: Why It Happens, the Fiber Math for a Paleo Day, and What the Trials Say Helps