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7 biggest benefits of protein bars for building muscle and losing fat

Written by John Davis

Last updated: November 8, 2022

Protein bars are a quick and easy way to deliver protein to your body when you’re too busy for a healthy meal.

Though there are a ton of low-quality protein bars out there that aren’t much more than candy bars with a bit of protein powder added in, there are still some great protein bars that can be incredibly handy for losing weight or gaining muscle.

We’ve reviewed the science of protein supplementation in-depth and distilled that knowledge into these tips for making the most out of a high-quality protein bar.

Protein bar benefits

1. You need protein to put on muscle mass

It’d be great if you always had fresh-cooked lean protein meals ready to go, but most of us don’t.

That’s where protein bars come in. Pioneered by sports-focused companies like PowerBar and Clif Bar, the category has a giant market size today.

Protein bars are useful primarily for three things: gaining muscle, losing weight as a meal replacement, and as a versatile, all-around snack when you are on the go.

The ingredients of a protein bar dictate, more or less, to what extent it’s useful for each of these categories.

2. The main benefit of a protein bar is the quality and dosage of its protein content

What does protein do for you? It’s no secret it helps you build muscle.

That’s been so universally accepted as doctrine now that it hardly needs proof. But in case you had any doubt, plenty of science has demonstrated that supplementing with protein works definitively. Here’s something you might not know–it works for everyone, not just young, fit-looking lifters.

A 2012 study published by scientific researchers in The Netherlands demonstrated that protein supplementation helps frail elderly people add muscle during a weightlifting program (1).

This study used a twice-daily supplement of 15 grams of protein, which is right in the ballpark of what you’d find in a decent protein bar. So, if adding muscle mass with protein works for 80-year-old elderly people, it’s definitely going to work for you.

If you want to add muscle mass, your number one priority is its protein content. So check that nutrition label and get a bar that packs in as much protein as possible.

3. Protein is useful for weight loss too

For weight loss, it’s a little different. Oddly, you still want a good amount of protein. This was demonstrated in a 2008 study in the journal Nutrition and Metabolism (2).

In the study, one group of subjects was given a protein supplement drink to take daily, while the other group was given a similar carbohydrate-only drink.

During the course of the study, the subjects who took the protein supplement were able to lose more body fat while maintain their lean muscle mass. If you want to progress more quickly to your desired body shape, this is definitely the way to do it.

At first, it seems a little off: how could eating more protein help you lose weight? We know protein helps build muscle, so the muscle mass maintenance makes sense. But what about losing fat?

4. Protein induces a feeling of satiety

The best explanation has to do with satiety, or the feeling of fullness you get after a meal. It’s a well-known phenomenon that protein increases fullness to a much greater extent than an equal amount of calories from carbohydrates.

Some possible mechanisms for this were laid out in a 2008 scientific article by European researchers (3). The details of this aren’t important; the bottom line is that protein fills you up, so keep the protein content high.

5. A protein bar with fiber is great for weight loss

The other part of the weight loss equation is fiber content. Dietary fiber is also known to increase satiety, and one repeated observation that obesity researchers have made is that people who eat more fiber tend to weigh significantly less.

As far back as 2000, nutrition researchers were outlining the function of dietary fiber in increasing fullness and fighting weight gain (4).

What’s this mean? If you want to use a protein bar as a meal replacement, look for something that combines high protein and high dietary fiber content.

6. Protein bars for weight loss should be low in sugar

Lastly, if you want to lose weight, you should also keep the sugar content low. From the looks of the epidemiological research, sugar is public enemy number one in the fight against obesity.

Multiple large-scale long-term studies have found an association between sugar intake and weight gain, as well as the negative health effects associated with it, like metabolic syndrome and type two diabetes.

An influential paper published in 2001 in the Lancet by Dr. David Ludwig and other researchers at Harvard University and Boston Children’s Hospital found that each additional serving of sugar-sweetened drink per day, body mass index increases by 0.24 kg/m2 –and remember, it only takes a few points of BMI to tip you from healthy to overweight, or from overweight to obese (5).

The American Heart Association recommends a maximum of 37 grams of added sugar per day for men, and only 25 per day for women (6).

Considering that some protein bars have over 20 grams of sugar per serving, it’s pretty hard to stay below this limit if you are eating a sugar-laden protein bar.

So, the upshot of all this is that, for optimal muscle-mass benefits, focus on protein. For weight loss, keep the protein and fiber high, and the sugar low.

7. Taking a protein bar instead of a sugary breakfast can help control type two diabetes

Breakfast has long been suspected to play a role in weight loss and the maintenance of metabolic health, but recent research has provided experimental evidence that consuming a high-protein breakfast that includes whey protein (a key source of protein in most protein bars) can lead to improvements in the symptoms of type two diabetes (7).

By designing a breakfast intervention that used whey protein to deliver 28 grams of protein, the researchers were able to examine the effects of this type of intervention compared to a similar breakfast that was not high in whey protein.

They found that the intervention created more favorable changes in indicators of metabolic function and inflammation, concluding that a high protein breakfast aided by whey protein could be a useful addition to a treatment strategy for type two diabetes.

In the context of protein bars, a high-protein and low sugar protein bar could be a great way to achieve these beneficial metabolic changes, especially if it replaces an unhealthy breakfast that’s high in sugar or refined carbohydrates.

Protein bar side effects

Protein bars are just food. One of the nice things about protein bars is that they are, for the most part, just food. So they don’t really have any distinct side effects outside of their nutritional constituents.

Low-quality protein bars can have negative long-term health consequences. Of course, eating too much of the wrong kind of protein bar isn’t going to be the best thing for your long-term health.

Too much sugar, or not enough fiber, could have an impact on your metabolic health, so watch your proportions and watch your nutrition labels. This applies to everything else in your diet, too, not just protein bars.

A protein bar with too much sugar alcohol can cause stomach pain and bloating. One notable exception to this rule are protein bars with a lot of sugar alcohol in them. In high doses, these can cause stomach pain, bloating, and other gastrointestinal side effects.

A scientific article in the International Journal of Dentistry by Kauko K. Mäkinen describes in detail the uncomfortable side effects that some people experience when consuming sugar alcohols (8). If you know you get gastrointestinal troubles from artificial sweeteners, steer clear of protein bars that use them.

Protein bar usage

How often you want to take a protein bar is going to be contingent on what you’re trying to accomplish. For muscle building purposes, you’ll want to calculate your goal for your additional daily protein intake, then divide it by the amount of protein in your protein bar of choice.

In any case, you probably don’t want to eat more than three a day; otherwise that probably means you are getting lazy with your actual meals.

For weight loss, one or two protein bars per day is best. As a meal replacement for weight loss, you are looking at one or maybe two a day, either replacing lunch or functioning as a late brunch and mid-afternoon snack (without any lunch in the middle).

Even while on a diet, you still want a real breakfast and dinner, since that’s the best way to get your fruits, vegetables, and fiber in your diet. Those are important for losing weight, too.

Target 1.6 to 2 grams of protein per kg of body weight to build muscle. If you are taking a protein bar for adding muscle, you know that adding muscle mass requires at least 1.6 grams of protein per kilogram of body mass per day, and perhaps as much as 2.0 grams per kilo per day or more.

Of course, you don’t want to rely on protein bars for your only dietary source of protein, as other sources like chicken and salmon are high in protein and have additional benefits.

Aim for 50 grams of protein per day for weight loss. For weight loss, most research indicates that supplementing with around 50 grams of additional protein per day can help you capitalize on the thermogenic and appetite-suppressant effects of protein. That might be two protein bars per day, or a protein bar plus a protein shake.

For best results, you’ll want to consume protein early in the day if you are shooting for weight loss. Protein at night won’t be as helpful, because the appetite suppressant effects won’t be as useful.

Protein bar benefits FAQ

Q: Are protein bars actually good for you?

A: A lot depends on the specifics of the protein bar. If we are talking about a protein bar that supplies 15 or 20 grams of protein, some dietary fiber, and barely any sugar, then yes, a protein bar is a great way to add protein to your diet and swap out for a potentially less healthy meal if you are on the go.

On the other hand, a protein bar that provides a mediocre amount of protein, no fiber, and a lot of sugar is not much better than a candy bar in terms of health.

Q: Do protein bars make you put on weight?

A: Protein bars can seem a bit paradoxical because they are touted as a way both to lose weight and to put on muscle mass. Which of these effects they will have depends entirely on the context of your diet and lifestyle when you are taking protein bars.

If you are taking a protein bar as part of a high calorie, high protein diet and are doing a lot of weight training or other resistance training, you’ll find that you’ll put on muscle mass fairly easily.

On the other hand, if you are using protein bars as a part of a diet that is generating a caloric deficit, and you are focusing more on aerobic exercise, a protein bar is more likely to help you lose weight.

Q: Are protein bars good for weight loss?

A: When used correctly, a protein bar is a great way to assist with a weight loss program. For maximum success, use a protein bar in lieu of a less healthy meal, like a sugary cereal for breakfast or a mediocre cafeteria lunch.

Protein has two primary advantages for weight loss: first, it induces a thermogenic effect compared to an equal amount of calories from carbohydrates or fat. Second, it induces the feeling of satiety, or fullness, to a much greater extent than other macronutrients.

This second effect means that high protein meals and snacks are particularly well-suited for consumption earlier in the day, since the satiety effect will make you eat less at future meals (i.e. lunch and dinner). So, protein bars are good for weight loss, but only when used intelligently.

Q: Can protein bars help you feel full?

A: A good protein bar has two ways to induce satiety (the opposite of hunger): it can rely on the appetite-suppressing effects of its protein content, and it can rely on the fullness-inducing effects of its fiber content.

The best protein bars do both. Animal sources of protein (think whey or bone broth protein) do a better job of inducing satiety thanks to their high BCAA content, and a good protein bar will also use a solid source of dietary fiber to add some bulk, which also helps tamp down on hunger cravings.

Related: Our best protein bar picks


Protein bars are a great substitute for carb and sugar-packed snack foods, and are the perfect way to keep your protein intake high when you’re on the go.

Whether you’re a serious athlete or a regular person just trying to lose weight, keeping some protein bars handy can be incredibly useful for healthy nutrition when you’re on the go.


John Davis

John Davis is a Minneapolis-based health and fitness writer with over 7 years of experience researching the science of high performance athletics, long-term health, nutrition, and wellness. As a trained scientist, he digs deep into the medical, nutritional, and epidemiological literature to uncover the keys to healthy living through better nutrition.