Nutrisystem Side Effects: What to Know Before Signing Up

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Written by Megan Ayala. Last Updated: January 10, 2023

According to the Centers for Disease Control and Prevention, in 2017-2018, the prevalence of obesity was a staggering 42.4 percent [1]. It is no wonder why weight loss programs like Nutrisystem are so highly sought-after.

After all, a study conducted in 2013 by the American Journal of Hypertension came to the conclusion that Nutrisystem’s diet program was not only effective at reducing weight and fat, but it was also good for reducing unhealthy blood pressure levels [2].

Despite the diet being very effective at helping reduce fat and overall weight loss and unhealthy blood pressure levels, you do need to be aware of some potential side effects. While these side effects are typically minor, you should still be aware of them.

Before we get into some of the different side effects that you can experience while following the Nutrisystem diet, we will be going over what Nutrisystem is, how it works, and what makes it different.

What is Nutrisystem?

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Nutrisystem isn’t one of those weight loss programs that promise you the moon. Instead, it is a practical weight loss system designed to make it convenient to stick to a meal plan that is optimized for weight loss. This meal plan is both customizable and proportioned. The program itself is designed to be easy-to-follow and balanced.

With the Nutrisystem program, you get delivered ready-to-eat meals that are pre-proportioned. It encourages you to eat every 2 to 3 hours in order to keep your metabolism revved up. The meals and snacks are small but nutrient-dense.

With the program, you are also supposed to supplement with fresh groceries in order to get more healthy vitamins and minerals into your daily diet.

Learn More About Nutrisystem by Reading our Full Review

Top Potential Side Effects Of The Nutrisystem Diet

1. Nutrisystem and Stomach Problems

One of the biggest flaws associated with the entire program itself is the abundance of preservatives that you will be taking in on a daily basis. This is the cost of convenience. The majority of the meals that you will be eating while on the Nutrisystem diet come pre-packaged and ready-to-eat.

Therefore, you will be consuming a lot of preservatives while on it. The packaged food that you are eating is going to contain a lot of preservatives in order to keep it from spoiling. While they won’t necessarily directly harm you, your digestive system may not handle the spikes of preservative intake as well as others.

After all, studies have shown that many people are sensitive to various preservatives and chemicals like nitrates, aspartate, and sulfites. In some, foods with these chemicals can cause headaches and migraines [3].

2. Bloated and Gassy from Nutrisystem (Thanks, High Fiber)

Because a lot of the system is designed around providing you with high amounts of fiber to curb cravings and to minimize hunger, you should expect to experience a lot of the side effects that come with increasing your fiber intake.

While fiber is an essential component of a well-optimized diet, getting too much of a good thing is rarely a good thing. That is exactly the case with fiber.

Studies have shown that when people consume too much fiber throughout the day, they can experience numerous side effects. One of them would be gastrointestinal distress which can include everything from bloating to cramping to constipation [4].

Some of the other symptoms that you can experience when you consume too much fiber can be caused by the fiber limiting the absorption of essential minerals. This is due to the fact that fiber can bind directly to them which can cause you to become deficient in them.

3. Normal Side Effects From Switching Diets

One thing to note is that you can always expect to experience a range of side effects when you are making such a dramatic shift in your diet. If you are going from a diet full of nearly 2,000 calories and you are cutting it down to a caloric deficit, you will experience side effects. These side effects can include fatigue, headaches, cramping, and more.

This will primarily be dictated by what kind of diet your body is used to.

If your body is used to cramming down a lot of simple carbohydrates, you will shock your body when you switch to Nutrisystem because it features a lot of low-glycemic carbohydrates that don’t impact your blood sugar levels nearly as much.

4. Hunger Pains

While the entire point of switching to a weight loss program like Nutrisystem is to avoid overeating and to lose weight, you will experience the side effect of being hungry initially. While the Nutrisystem does pack in a lot of satiating nutrients including a lot of lean protein and fiber to help keep you feeling full, you are bound to experience some hunger pains during the early going.

This is nothing to be alarmed about as it is completely normal.

5. Quick Weight Loss That Stalls

Another thing to be aware of would be the fact that you can expect to lose a good amount of weight during the initial stages of the diet.

Your first week or two will be priming your body to enter a fat-burning state. Because of this and combined with the water weight, you will shed, you can expect to experience fairly substantial results within the first few weeks. This is typically what you should expect whenever you are switching to any kind of diet.

However, once your body becomes accustomed to the diet itself, the weight loss will stall and slow down. Don’t be alarmed when you begin experiencing a slow-down in results as it is completely normal.

6. You May Lack Energy

As mentioned, one of the most reported side effects that people experience when they are switching diets is a lack of energy. One of the main reasons for this has to do with diets inherently being caloric-restriction based. Because of this, you have to sacrifice certain foods in order to maintain a caloric-deficit.

This typically means shedding foods that contain essential nutrients. For this reason, you are recommended to take a multi-vitamin along with the diet itself according to Nutrisystem’s website [5].

This shows that you are simply not going to be taking in all of the necessary vitamins and minerals while on the program due to the restrictive nature of any plan that is based on a reduced-calorie diet.

7. Nausea on Nutrisystem?

While most people shouldn’t experience nausea while on the Nutrisystem diet, it is a possible reported side effect for some folks. This may be because of nitrates, or could even be because you aren’t eating enough. If you experience this, check in with Nutrisystem customer service and see what they suggest as a possible solution.

8. Not Pooping on Nutrisystem

This is an embarrassing subject for most, but is a topic we’ve seen related to possible Nutrisytem side effects. This could be from a lack of fiber, not enough water, or a host of other issues.

Again, check in with Nutrisystem if you experience constipation while following their diet. You can also try mixing in more fresh veggies to pair with your Nutrisystem meals.

9. Mood Swings

One of the side effects that may be more noticeable would be mood swings. As mentioned, this diet encourages the intake of low-glycemic carbohydrates. Therefore, you can expect to experience some of the common benefits associated with low carbohydrate diets. Once you are actually on the diet and your body has become accustomed to the change in carbohydrate intake, you will likely experience the opposite effect with your mood improving. However, during the adjustment phase, you can expect minor swings that can make you a little bit more moody than usual.


Overall, the Nutrisystem has relatively minor side effects. In fact, many people who follow the Nutrisystem program experience little to no noticeable side effects at all. This primarily comes down to your individual body type, your previous diet, your fitness levels, and other things that can influence your results.

If you are looking to switch to the Nutrisystem diet to lose weight, you shouldn’t let the minor side effects discussed above discourage you. The diet program has a lot of success stories that prove its effectiveness.

The diet is based on sound weight loss principles that include incorporating a diet consisting of high amounts of lean protein, high fiber, and low-glycemic carbohydrates in order to shed excess fat.

If you do experience any side effects while following Nutrisystem, you should consult with your medical doctor, and also check in with Nutrisystem support staff, as they’re there to help on your weight loss journey.

If you are thinking about following the Nutrisystem diet, keep in mind you may or may not experience some of the side effects listed above. That being said, the results are very well worth any short term discomfort.

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