Does protein powder make you gain weight or lose it?

Protein powders are considered a convenient way to boost protein intake, but you may wonder whether using them could lead to weight gain. While a high-protein diet is unlikely to cause weight gain on its own—and may even support weight loss, especially when paired with exercise—it's important to understand that protein needs vary from person to person. Factors like age, sex, weight, and activity level all play a role in how much protein you require. 

If you’re looking to supplement with protein powder, it can be a helpful addition to your diet, but it’s essential to be mindful of potential risks associated with dietary supplements. Here’s what you need to know about how protein shakes fit into your fitness goals.

Everyone’s protein needs are different. The ideal amount of protein your body needs will depend on a few factors, including age, sex, weight, activity level, and whether you’re pregnant or breastfeeding. The US Department of Agriculture (USDA) offers a wide range of recommendations for adults, suggesting that protein should account for anywhere from 10 to 35 percent of your daily calorie intake — equivalent to 50-175 grams of protein per day for a 2,000-calorie diet, for example. For a personalized recommendation for daily protein intake, plug your info into the USDA’s Dietary Reference Intakes calculator.

You can reach your quota by including a variety of protein-rich foods in your diet, including meat, poultry, fish, dairy, eggs, and legumes. However, even foods that aren’t thought of as sources of protein — like asparagus or brown rice — also offer small amounts of protein that add up throughout the day. If you’re having trouble getting enough protein through whole foods, you may want to consider boosting your consumption using supplements like protein powder.

When most people talk about gaining weight, they mean gaining body fat. On its own, protein powder isn’t likely to make you gain fat. But when you look at the big picture, it could factor in. The main cause of weight gain is excess energy consumption — i.e., a calorie surplus, eating more calories than you burn. (Weight management is quite complex, with a lot of different factors at play, but this is the root of weight gain at the simplest level.) If you add a significant amount of protein powder to your diet on top of your usual meals, and that pushes you into excess calorie intake, it could potentially lead you to gain weight as fat.

Protein powder will also affect your body differently depending on exactly what’s in it. For example, some protein powders contain carbohydrates (including sugar) and fat in addition to protein. In excess, these nutrients can contribute to excess calorie intake and cause weight gain. It also depends on what you are mixing the protein powder into. Some people mix protein powder into water while others mix it into milk or yogurt. Remember that the vehicle you are using to consume the protein powder comes with its own calories. 

Certain ingredients in protein powder can also cause bloating — which isn’t true weight gain but may feel like it. Sugar alcohols (e.g., sorbitol, xylitol, maltitol), for example, are often used to make protein powder taste good without adding calories or sugar, but they can cause bloating and GI symptoms in some people. 

Outside these factors, however, protein powder generally should not make you gain weight. In fact, of the three macronutrients (carbohydrates, fats, and proteins, which constitute all of our food), protein may be the least likely to make you gain weight as fat on your body. A 2017 review of research found that consuming too many calories via a protein-rich diet leads to lower gains in fat mass than are induced by diets high in carbs or fats. This protective effect against fat gain seems to be even more potent when combined with resistance training.

It can. Researchers can’t say that protein powder specifically is what influences weight loss, but eating more protein, in general, seems to make a positive impact. Numerous studies show that eating a high-protein diet (between 18-45 percent of total calories) helps induce fat loss, whether or not you’re in a calorie deficit. The effects are strongest when a high-protein diet is paired with exercise, though research shows that increasing protein intake alone (while reducing carbohydrates) may still help you lose weight.

There are a few different reasons why eating lots of protein may aid weight loss and help you maintain a healthy weight. For one, protein helps promote feelings of satiety, which can help you eat less over the course of the day or make smarter food choices by staving off hunger between meals. This is key because one of the most common weight-loss strategies involves creating a calorie deficit (consuming fewer calories than you’re burning), often through eating less and exercising more.

Protein also helps maintain and build muscle mass, which boosts your metabolism. More muscle mass is associated with a higher basal metabolic rate, meaning your body naturally burns more calories even at rest. This is especially important when you’re eating a low-calorie diet since operating on a calorie deficit can result in muscle loss — unless you’re eating plenty of protein. Research shows that a high-protein diet helps preserve muscle mass during a moderate calorie deficit, particularly when paired with resistance exercise.

Protein may stoke your metabolism in another way. After you eat, your body uses energy to digest your food, contributing a small but significant portion of your overall metabolic rate and calorie expenditure for the day. This is called the “thermic effect of food.” Your body has to work harder to digest protein than carbs or fats, which means it revs your metabolism more than the other macronutrients. Researchers think this extra work your body has to do plays a role in protein’s weight loss effects as your body burns more calories to digest it.

There are many different types of protein powder to choose from, each with advantages and disadvantages. In terms of weight loss and maintenance, we don’t have clear evidence on whether one protein source is better than another. 

Protein supplements vary by brand and flavor, so you may need to experiment to find what works best for you. Here’s an overview of some popular types:

• Whey protein: Whey is a complete protein that comes from milk. It’s one of the most thoroughly researched proteins and is shown to be great at stimulating muscle growth. It’s rapidly digested by the body but can cause digestive discomfort, especially for those with lactose intolerance. (Opting for whey protein isolate can help, as it has very little lactose.)

• Casein protein: This is another complete protein from milk. It’s absorbed more slowly than whey and reduces muscle breakdown, which is why some people supplement with casein before bed to help with recovery.

• Egg protein: Egg is a complete protein that’s digested slowly. It has a neutral taste and can be a good choice for someone who wants a dairy-free animal-based protein powder.

• Soy protein: Soy is a complete, plant-based protein that’s shown to promote similar muscle mass and strength gains as animal protein. It’s a great choice for vegans or vegetarians who want to avoid animal products, though it may cause bloating, gas, or digestive issues in some people.

• Pea protein: This is another complete, plant-based protein suitable for vegans or those who don’t want to consume dairy or egg. It’s easily digested and, depending on the product, can be high in fiber and micronutrients.

It’s important to know that the US Food and Drug Administration (FDA) doesn’t regulate dietary supplements the same way it regulates food and drugs. The FDA doesn’t approve dietary supplements for safety and effectiveness before they go to market, meaning it’s up to manufacturers to monitor and accurately report what’s in their products. As a result, some products sold to consumers may have potentially dangerous ingredients or not contain what the label says.

To minimize your risk and ensure you’re buying a high-quality product, look for a third-party certification like NSF Certified For Sport, which verifies that products don’t contain unsafe levels of contaminants or prohibited substances and that the label matches what’s actually inside the product.   

Many different factors influence how much protein you should eat daily and via protein powder, including age, body composition, total calorie intake, and how much and how hard you’re exercising. The ISSN recommends spreading out your protein consumption evenly throughout the day to best support muscle protein synthesis, so you don’t want to get all your daily grams from a single giant protein shake. If you’re trying to lose weight by restricting calories, the ISSN recommends aiming for three to four meals daily with 20–40 g of protein per meal. 

A single serving of protein powder generally contains 20-30 g of protein, so one serving should be a reasonable dose as a post-workout snack or as an addition to a meal. Always follow the directions on the packaging, including taking note of how many servings can or should be consumed per day, if specified.

Protein is an important nutrient for overall health, and getting enough can significantly impact your fitness goals. Overall, adding extra protein to your diet via protein powder isn’t likely to make you gain weight unless you’re eating a lot of extra calories each day. When combined with physical activity, eating a high-protein diet with the help of protein powder may even help you gain muscle and lose fat. Just keep in mind that while protein powder can help you get enough protein, it’s not always necessary — there are plenty of high-protein foods out there to help you get your fill.

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Every article on Health Guide goes through rigorous fact-checking by our team of medical reviewers. Our reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the writer.

Current version

November 05, 2024

Written by

Lauren Mazzo

Fact checked by

Raagini Yedidi, MD

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About the medical reviewer

Raagini Yedidi, MD

Raagini Yedidi, MD, is an internal medicine resident and medical reviewer for Ro.