Is your weight-loss plan causing constipation? A few simple lifestyle changes can help

Sue Heikkinen, MS, RDN, CDCES, BC-ADM, ACE-PT - Registered Dietitian Nutritionist and Certified Diabetes Care and Education Specialist

Constipation is a common complaint from people on weight-loss diets. Here are causes, plus tips to help prevent and manage this bothersome condition.

Weight loss and constipation–unfriendly but common partners

You may have days where you aren’t “regular,” but what actually is constipation? The American Gastroenterological Association (AGA) defines constipation as when you have infrequent (less than three times a week) or hard-to-pass bowel movements.

Not only is constipation uncomfortable, but it can also increase the risk of hemorrhoids and diverticulosis (pouches in the walls of the colon). Constipation can be a challenge with some weight-loss plans, but there are strategies to help keep your digestive tract in tip-top shape.

6 Reasons your weight-loss plan may cause constipation

1. Rapid weight loss or calories too low

Constipation is a risk with any reduced-calorie weight-loss plan. It is typically a result of decreases in the volume of food waste and the rate at which waste is moved through the digestive tract.

Rapid weight loss, particularly with a very low-carb plan, can increase fluid loss, leading to hard stools. Severely restrictive diets can lead to constipation by slowing the metabolic rate, more the reason to avoid extreme weight-loss plans.

2. Fasting or skipping meals

Although intermittent fasting is a popular weight loss approach, constipation risk is a potential drawback when you go a long time without eating. Eating a meal signals the digestive tract to move waste along. Breakfast is the most important meal in terms of prompting digestive tract movement. If you follow an intermittent fasting plan, consider moving your eating window earlier to take advantage of the morning meal effect on your bowels. If you tend not to eat breakfast, see if adding breakfast to your plan reduces constipation.

3. Not enough fiber

Fiber is an indigestible form of carbohydrate that helps soften and add bulk to the stools, helping them move through the digestive tract faster and more easily. If you cut whole grains, fruits, and legumes to reduce calories and carbs, you will likely lack fiber. Boost fiber with lower-carb options such as nuts, seeds, berries, chia, and flaxseeds.

Track your fiber with MyNetDiary to ensure you aren’t short-changed on this digestive ally. The USDA Dietary Guidelines recommend 14 grams per 1000 calories, though it may be wise to aim for a bit more if you are on a low-calorie weight-loss plan. You can adjust your goal in Settings.

You may get enough fiber but not enough of the right kind of fiber. Well-formed poops rely on two types of fiber, insoluble and soluble. Insoluble (doesn’t dissolve in water) fiber provides bulk to the stool, helping it move faster through your digestive tract. Whole wheat products, nuts, and vegetables are good sources of insoluble fiber. Soluble (absorbs water) fiber makes the stool softer and easier to pass. Soluble fiber-rich foods include barley, carrots, oats, flaxseed, beans, and psyllium.

4. Not enough fluid

About 20% of your water intake comes from food sources. So when you eat less, you are reducing this hidden fluid source. On the other hand, you may need more fluids when you cut out sugary beverages (good for you!) but fail to sufficiently replace them with water or other no-calorie drinks.

Also, don’t overlook the importance of extra fluid as you increase fiber, whether from foods or supplements. A high-fiber diet without adequate fluid can actually cause stools to be more challenging to pass.

A goal of at least one mL of fluid per calorie you consume is a good place to start. For example, if you consume 2000 calories, your fluid goal is 2000 mL (or about 8 cups). Set your fluid goal and track it in a snap with MyNetDiary’s Water Tracker.

5. Lacking fruit

Many weight-loss plans limit fruit to curb calories and carbohydrates. Of course, fruit is more than a source of fiber. Fruit is hydrating, and many are high in the natural sugar fructose and sugar alcohols such as sorbitol, both of which can draw more fluid into the digestive tract. Indeed, some people notice that too much fruit can trigger loose stools.

Prunes aren’t the only fruit with a reputation for helping provide constipation relief. Kiwifruit has benefits for constipation with less bloating and gas than eating prunes. Research demonstrates improved regularity from eating two of these fuzzy fruits a day.

6. Medications or supplements

Have you added new dietary supplements to your plan, or are you eating a lot of fortified shakes or bars? Check that you aren’t getting excess iron or calcium, which may contribute to constipation.

If you are taking a prescription weight-loss medication, note that constipation is also a possible side effect of many of these drugs. Discuss any concerns about medications contributing to constipation with your doctor or pharmacist.

What can you do to prevent constipation?

Perhaps you’ve upped your fiber and fluid, yet constipation is still an issue. Thankfully, there are additional strategies you can try.

Move more

Not only is exercise an essential part of any weight-loss plan, but it helps move your bowels and strengthens the muscles involved in digestive health. Aim for at least 30 minutes of activity most days. Upright activities such as walking, running, or dancing may be especially effective, as they provide the effect of gravity combined with the impact of movement.

Don’t ignore the urge to go

The signal can diminish if you ignore the initial urge to have a bowel movement. Meanwhile, the stool hardens and becomes more difficult to pass. Even though the timing may not be convenient, it is worth responding to “nature’s call” to prevent constipation issues later. Consider building a few minutes into your morning routine to allow this valuable time in the bathroom.

Add a fiber supplement

Despite your best efforts, getting enough fiber from food on a weight-loss diet may be challenging, especially if you strictly limit carbohydrates. Consider adding a fiber supplement such as psyllium (Metamucil), which may be the most effective form of fiber for constipation.

Try an over-the-counter remedy

If lifestyle approaches alone don’t do the trick, non-prescription laxatives may be useful. Check with your doctor first to ensure they are safe for you to use regularly and which products would be most appropriate.

Create a custom tracker for your gut

MyNetDiary allows you to create a custom tracker for anything you desire. Consider tracking the frequency of bowel movements and stool consistency to identify connections between food choices, activity, supplements, and other factors.

You may also use MyNetDiary’s "Notes" feature for any additional observations you want to record.

Don’t accept constipation as an unavoidable part of losing weight.

Getting enough fluid and fiber and adopting a healthy and active lifestyle are great strategies to promote regular bowel movements. Know when it is time to get more help. According to the AGA, you should talk to your doctor if any of the following apply:

• Symptoms last longer than three weeks
• Symptoms are severe, including pain with passing stool
• You notice stools are consistently thinner
• You notice blood in the stool, or you have black stools
• You have anemia, or
• In addition to other symptoms, you have unexplained weight loss. However, unexplained weight loss can be challenging to notice when actively trying to lose weight.

Related content

Constipation - National Institutes of Heath

How to figure out how much water you should drink plus an easy way to track it

Why you should eat good sources of fiber every day

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Weight Loss->Weight Loss Tips & Quips Other Health Issues->Gastrointestinal (Gut)

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