Last Updated On January 1, 2026
It's a question many of my clients have asked me over the years -- does protein powder cause weight gain?" And I can see why.
Some people say protein shakes help lose weight, while others say it causes weight gain. So which is it?
To help you out, I will answer this question in detail, covering EVERYTHING you need to know about protein powder and gaining weight.
Can Protein Powder Cause Weight Gain?
Yes, protein powder can cause weight gain. However, only if you’re in a calorie surplus.
When Working Out
If you’re like me and work out regularly, protein shakes are an awesome way to up your protein intake so you can aid muscle growth.
However, consuming protein shakes can make you gain weight due to you adding more calories to your diet. So it's CRUCIAL to monitor your overall calorie intake and adjust it accordingly. If you do find yourself gaining some body weight, I wouldn’t be overly concerned immediately.
A 2018 study found that whey protein shakes and resistance training increased lean muscle mass and had little effect on body fat mass.[1] In other words, the participants’ weight gain was muscle mass. (Phew, I was getting worried; I love a protein shake).
What If I Am Not Working Out?
If you’re not working out, your body still needs protein, and if you’re in a caloric surplus, you’ll gain weight.
Protein is a crucial macronutrient that your body needs to function optimally.
Yet, it DOESN’T mean you need to take whey protein supplements. You can get enough protein from food. Such as:
Sometimes it's more convenient to use protein shakes. I love throwing a few scoops of whey protein into my shaker as a snack. It's quick and easy.
If you’re not working out or adjusting your diet accordingly, adding protein powder to your calorie intake will result in weight gain. And as you're not working out, this weight gain will likely be fat. Which is the last thing you want, right?
Specifically For Females
Females, are you worried about gaining weight if you drink protein shakes? If so, DON’T. WORRY.
You'll be happy to know the rules for males and females are the same. You'll only gain body weight if you're in a calorie surplus. The extra calories from the protein shakes need to be considered if you're tracking your macros.
If you’ve seen some “Doctor” or “Influencer” tell you that protein shakes are bad for women and make you gain weight, quickly UNFOLLOW them and throw that notion in the trash. After all, protein powder is no different from other high-protein foods, but it can be more convenient.
Different Types of Protein Powder And Their Effect On Body Fat
There is a wide range of ways to get protein in your diet, with protein powders being one of them. And there are MANY different types of protein powders for you to consider.
Whey Protein
Whey protein is the MOST COMMON protein powder around, and you’ll see many gym goers supplementing with it.
It's derived during the cheese-making process and contains fewer calories than other types of protein shakes. It can help you lose weight so long as you're in a calorie deficit (eating less calories than you burn).
I'm a HUGE fan of whey protein and use it to boost my daily intake. It’s often available in two forms:
- Whey Protein Concentrate (70-80%)
- Whey Protein Isolate (90-95%) - Perfect if you have lactose intolerance.
Whey Isolate is excellent for supporting your weight loss goals.
Casein Protein
Casein is a milk protein that is slow releasing and takes longer to digest. You can often find it in meal replacement shakes, as it keeps you feeling fuller longer. Studies have shown that it could be an excellent protein for losing weight.[2]
Hemp Protein
Derived from the cannabis plant, this protein is rich in branched-chain amino acids, “aka” the building blocks of muscle. While it contains a lower amount of protein (15g per serving), the extra protein will help with building muscle tissue. And could be used alongside a healthy diet to help you lose weight.
Egg Protein
Egg protein helps with muscle repair and has been shown to reduce appetite and support weight loss goals.[3] It’s a great source of protein, in my opinion. Egg protein has around 24g per scoop.
Soy Protein Powder
Soy protein is EXCELLENT for vegans and contains essential amino acids, which your body needs to gain muscle mass. So how much protein does it have? Soy protein has around 25g per scoop.
Pea Protein
Like the other proteins on this list, pea protein can be used to build muscle. It’s not my favorite protein shake to drink (I think they taste awful compared to other sources), but it can be used to improve your body composition.
How Can Protein Powder Make You Gain Weight?
Protein powder can make you gain weight in several ways:
Too Much Protein Powder
Like anything, too much of a good thing is never good.
The same can be said for protein powder. While I’m a HUGE advocate of having a high-protein diet, if you add protein powder to your diet, you might consume too many calories. Doing so will cause you to gain weight.
Wait… I thought protein powder was good for me?
It is, but like all foods, it contains calories. And they should always be accounted for.
Calories in Protein = 4 per gram.
While protein powders aren’t high-calorie foods, the calories do add up. So please don't make the mistake of thinking they don't count.
Not Measuring Protein Powder
Most protein powders come with a scoop. (Which is ALWAYS at the bottom of the tub…talk about a nightmare).
However, sometimes the scoop is smaller than it needs to be. If so, the protein shake’s nutrition labels will tell you to have 1.5-2 scoops per serving.
If you misread this or miss it all together…like I’ve done in the past (oops), you might be getting less protein powder than you think.
This mightn’t seem like an issue, but if you’re mixing your protein powders with other ingredients, you could end up with more carbs than protein.
However, this can work the other way around too. If you don’t read the label correctly, you might end up with several heaped scoops of protein powder in your shake rather than the one that’s needed. Resulting in more protein in your shake and excess calories. This could lead to weight gain.
It’s one of the leading protein powder mistakes I’ve seen gym-goers make.
Tips From A Trainer!
Always read the nutrition label thoroughly before you start taking protein powder. It’ll stop any mistakes from occurring.
Buying Whey Protein Concentrate
Before I start this section, there is NOTHING wrong with whey protein concentrate. It’s an excellent source of protein for muscle building and can help you reach your fitness goals.
However, your body won’t thank you if you're lactose intolerant. (And neither will the rest of the gym-goers).
By drinking whey protein concentrate, your overall health might be taking a hit. Your gut will likely inflame, leading to several issues, including SEVERE bloating. The bloating could make you look like you’ve gained weight.
A quick way around this is to use vegan protein sources or Whey Isolate (my preferred protein source).
Relying On Protein Powder As The Only Protein Source
Vegans and Vegetarians, I’m calling you out on this one. - As you’re usually the main culprits. (Sorry, it’s TRUE).
If you rely solely on protein supplements as your only protein source, they might make you gain weight.
There are two reasons why I’ve found this happens:
- Protein shakes aren't as filling as whole foods (solid food). As they don't fill you as much, you'll be more likely to eat other foods high in carbs or fats. These additional calories will result in excess weight gain.
- Your diets are low in protein, but you're already hitting your daily calories from other "real" food sources. The extra calories from the shakes will cause you to gain weight.
As you can see, both are a result of a calorie surplus.
You can work around this by ensuring you have a balanced diet of healthy foods (which can include some processed foods occasionally). And that you’re actually eating protein rather than relying 100% on protein powder blends. Protein-rich foods for Vegans and Veggies are:
How Much Protein Do You Really Need?
The amount of protein you need will depend on several factors:
If you’re working out
If you’re working out daily, your protein NEEDS to be higher.
Physical activity like resistance training causes micro-tears in your muscles that must be repaired. This is where protein helps. You need around 0.8 grams of protein per lb of body weight.[4]
If you’re NOT working out
As you're not working out, your protein requirement won't be as high as somebody performing regular exercise.
HOWEVER,
Looking to build your muscles
Want to build muscle? Then there are two things you need:
- Regular strength training
- High protein diet including healthy fats
Eating more protein will help you start gaining weight (so long as you’re eating MORE calories than you burn.
If you want to build muscle, I’d recommend eating 1-1.2 grams of protein per lb of body weight. You can get protein from a protein shake or protein bars (both are convenient ways to boost your intake).
Looking to lose fat
If you're the average person looking for weight loss, you must keep your protein levels at around 1g per lb of body weight.
I recommend this amount as you want to maintain as much muscle mass as possible while the pounds drop.
Protein Powder & Fat FAQs
You should take 1-2 protein shakes per day to gain weight. The more shakes you have, the more calories you’ll be consuming.
For healthy weight gain, protein shakes should be used to supplement your diet. A convenient way is adding them between meals to boost your calorie intake.
Around 35% of your calories should come from protein (depending on your goals, body weight, and other factors).
You shouldn’t take protein shakes if you’ve got kidney issues (kidney disease). Doing so can cause harm, so always consult your doctor beforehand.
How To Choose The Right Protein Powder For You?
When it comes to choosing the right protein powder (or any good supplement) for you, you need to consider the following:
The protein you choose won’t directly cause weight gain, but the extra calories from the protein shake can make you fat IF they’re not taken into account.
You can avoid this by figuring out your basal metabolic rate (how many calories your body needs) and ensuring you don’t have too many servings.
References:
- https://academic.oup.com/nutritionreviews/article/76/7/539/4982765?login=false
- https://www.karger.com/Article/Abstract/12817
- https://www.mdpi.com/2072-6643/14/14/2904
- https://www.acsm.org/docs/default-source/files-for-resource-library/protein-intake-for-optimal-muscle-maintenance.pdf
Last Updated on January 1, 2026
