Whey protein 101: How to use it to build muscle and lose fat

• Whey is a protein supplement derived from dairy that contains all nine essential amino acids.
• Whey protein benefits include building muscle mass or losing weight.
• While whey is considered safe, it can cause acne, bloating, and unintentional weight gain.

Whey protein has generated quite the buzz among athletes and exercise enthusiasts as being the "gold standard" of protein supplements.

To determine whether whey protein deserves this title, we talked to two dietitians about the benefits, potential side effects, and different types.

What is whey protein?

Whey is a protein derived from dairy foods and is sold as a protein powder supplement.

One reason whey protein is the most popular protein supplement on the market is that it is a complete protein source, says Kelly Jones, RD, a dietitian and board-certified specialist in sports dietetics.

Complete proteins contain all nine essential amino acids your body needs to function normally. There are around 20 amino acids, but these nine can't be produced by the body itself, meaning you have to get them through your diet.

Medical term: Amino acids are components of proteins that play a role in digestive, hormone, and brain function.

In addition to being a complete protein, whey is also rich in leucine. Leucine is an amino acid known to help build and repair muscles, which is why many athletes tend to opt for whey protein supplements over other protein powders, Cassetty says.

While you can find leucine in some plant-based protein supplements, these supplements are less likely to be complete protein sources.

Here is a nutritional breakdown of your daily value (DV) of calories, protein, fat, and carbs in one serving - 30 grams - of whey protein.

Whey protein benefits

Related Article Module: 5 science-backed benefits of whey protein and common side effects

Whey is a convenient and effective supplement choice for those who need an extra boost in meeting their daily protein needs. Here are some of the benefits of adding whey protein to your diet:

• Whey protein can help you lose weight: A small 2008 study compared weight loss between a control group and a group that added whey protein to their diet. Both groups reduced their caloric intake by 500 calories. Those who consumed whey protein lost significantly more fat and retained more lean muscle mass than those who did not.
• Whey protein can help you gain weight: Adding whey protein into your diet is an easy way to increase your overall calorie intake, thereby assisting with weight gain. To gain weight healthily, aim to increase your calories by about 500 - or 4 servings of whey protein - per week and add resistance training to your exercise routine.
• Whey protein can help you build muscle: Adding whey protein to your diet, in combination with regular exercise and meeting your daily protein needs, has been shown to improve muscle building and muscle preservation.

Whey protein side effects

Whey protein is generally safe, but people with certain sensitivities may experience some side effects, like:

• Digestive issues like indigestion or bloating
• Unintentional weight gain
• Acne, due to it being a dairy product
• Low-level exposure to heavy metals, like cadmium or BPA

Supplements are not regulated by the FDA, meaning it is up to the manufacturers to evaluate the safety of the product. For this reason, it's important to be choosy and informed when it comes to picking a whey protein supplement.

"I highly recommend only purchasing whey protein products that are third-party tested," says Jones. This means an organization has independently tested the products in a supplement to make sure they are safe.

General advice: An easy way to tell if a food is regulated is to make sure the label says "nutrition facts" instead of "supplement facts," Jones says.

Whey protein may also interact with certain medications, reducing the body's ability to absorb some drugs. These include:

• Albendazole: a medication for certain parasites like tapeworms
• Alendronate: an osteoporosis medication
• Some antibiotics like Cipro and Penetrex

Important: Do not consistently substitute whey protein for whole foods. "If you're always reaching for whey powders instead of real food, you'll be missing out on the essential vitamins, minerals, and antioxidants that also support fitness, muscle repair, and overall health," says Jones.

Whey protein types

Whey protein types differ in how much they're processed and protein concentration. According to Jones, there are three types of whey protein:

• Whey protein isolate: This type is at least 90% protein. It is the most processed as most or all of the carbohydrates and fats are removed.
• Whey protein concentrate: This type contains 70% to 80% protein. It is the least processed and contains some carbs and fat. It's also usually the cheapest form of whey protein.
• Whey protein hydrolysate: This type contains 80% to 90% protein. It is the fastest and easiest type of whey to digest.

All types of whey contain small amounts of lactose, but whey protein concentrate contains the highest concentration.

Important: Because the lactose content in all types of whey protein is so small, it is tolerable for most people, even those with lactose intolerance, says Cassetty. "However, if you have severe lactose intolerance, isolate and hydrolysate may be preferable," she says.

If you are unsure which type of protein is right for you, consider seeking help from a physician or dietitian. "The right protein can vary for each person, depending on their digestion, performance, allergies, and health goals," says Jones.

Insider's takeaway

Whey protein is a convenient option that can help you meet your daily protein needs. It is safe for most people to consume and can help you reach various health goals including weight gain, weight loss, and muscle growth.

Whey protein is not regulated by the FDA, so it's important to do your research or consult a physician or dietitian before picking any protein supplement.

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