How Protein Shakes Help with Weight Loss and Belly Fat (2024)

Consuming more protein can help you feel full longer, build lean muscle, and support your metabolism. Different types of protein powders contain different nutrients.

Protein is an important nutrient for weight loss.

Getting enough protein may support a healthy metabolism and reduce your appetite. It may also help you lose body fat without losing muscle.

Protein shakes are a convenient way to add more protein to your diet. They’ve even been shown to aid weight loss.

Protein has been shown to help decrease hunger and appetite.

One key reason is that protein generally helps you feel full for longer. This is partly due to the release of fullness hormones GLP-1 and PYY.

Studies also show that higher protein intake may result in less hunger throughout the day.

In one small 2015 study, a high protein breakfast helped older women consume up to 135 fewer calories later in the day, compared with a low protein breakfast or skipping breakfast.

One 2016 meta-analysis of five studies also connected high protein intake and increased fullness. However, review authors caution that factors like body weight, eating behavior, and other health issues all play a role in the sensations of fullness.

Furthermore, another review published in 2020 reports that ingesting more than 35 grams (g) of protein at once appears most effective for effects like less hunger, a reduced desire to eat, and greater feelings of fullness.

Only a few studies have looked at protein shakes and appetite specifically.

One 2019 study with nine young women with obesity found that a whey protein drink actively reduced appetite.

In a 2021 study, participants given a high protein shake before their workout reported feeling less hungry after exercising than when given a lower protein shake with an equal number of calories.

Thus, while results are promising, numerous factors may affect the influence of protein shakes on appetite and hunger.

A high protein diet, especially when combined with strength training, can help build muscle.

Because muscle aids metabolism and energy production, building muscle is a great way to keep your metabolism healthy.

This is especially true if you follow a calorie-restricted diet to lose weight.

That’s because extreme calorie restriction may result in muscle loss and fat loss. This loss of lean muscle may slow your metabolism, making it easier to regain weight once you stop the restrictive diet.

Conversely, eating sufficient amounts of protein, combined with strength training, may help prevent this muscle loss and resulting metabolic slowdown.

A 13-week study in older adults with obesity found that those who consumed an extra 20 g of protein weekly (in the form of a shake) gained 2.8 pounds (lb), or 1.3 kilograms (kg), more muscle mass than those who ate less protein.

Plus, in a 6-week study, participants followed either a low or high protein diet, which included shakes. Each diet was calorie-restricted. Notably, participants following the higher protein plan gained 2.4 lb (1.1 kg) more muscle and lost 2.9 lb (1.3 kg) more fat.

Your body also uses more energy to digest protein than it does fat or carbs, which means your body burns more calories in the process. This effect, called the thermic effect of protein, may provide a slight metabolism boost.

Although few studies use protein shakes specifically, researchers generally agree that high protein diets are an effective way to lose weight and body fat.

A 14-week study gave women with overweight or obesity a resistance exercise program alongside a high carb or high protein, calorie-restricted diet. Those in the high protein group lost 1.7 times more body fat than those in the high carb group.

In a 12-week study, women with a moderate weight but high body fat percentage followed either a high or standard protein diet. Those on the high protein diet lost an additional 3 lb (1.4 kg) of body fat and around 1 inch (2.2 centimeters) in waist circumference.

The participants in the high protein group also retained significantly more muscle mass than those on the standard protein diet.

A 2020 review further suggests you can minimize weight regain by following a high protein diet in the first 3–12 months after losing weight. However, long-term studies must confirm whether this effect lasts beyond the first year.

Still, a small 2017 study found that when participants with excess weight drank low sugar protein shakes as part of a diet program, their weight loss improved.

Because so many lifestyle and ingredient variables are involved in weight loss studies, it’s hard to draw a direct connection between protein shakes and weight loss.

Protein’s effect on metabolism, appetite, and muscle mass may also help prevent regaining weight once you’ve lost it.

This effect should apply whether you get protein from shakes or whole foods.

One 2015 review suggests that higher protein intakes of 25–30 g per meal improve both weight loss and weight management. However, researchers caution that full adherence to a high protein diet, plus other lifestyle factors, is usually necessary.

Similarly, studies suggest that high protein diets result in less short-term weight regain after you lose significant amounts of weight.

All the same, more studies are needed.

Protein shakes are made by mixing protein powder with water or another liquid, plus optional other ingredients.

Although most people don’t need protein shakes to meet daily protein requirements, protein shakes can be convenient if you have limited access to high protein foods or experience trouble meeting your needs through food alone.

You can buy protein powder and mix it yourself or purchase premade liquid shakes.

Types of protein powder

Some of the most popular types of protein powder are:

• Whey protein: quickly absorbed, dairy-based, and contains all nine essential amino acids
• Casein protein: slowly absorbed, dairy-based, and provides all essential amino acids
• Soy protein: plant-based and offers all essential amino acids, plus soy isoflavones that may provide some health benefits
• Hemp protein: plant-based, contains all essential amino acids, rich in omega-3 and omega-6 fatty acids, and has a high arginine content
• Rice protein: plant-based but lower in the essential amino acid lysine
• Pea protein: plant-based and less allergenic alternative to soy and whey protein, but lower in the essential amino acids cysteine and methionine

Certain protein powders and drinks contain a mix of protein types.

For example, many plant-based brands combine types to diversify the amino acid profile. Some dairy-based protein powders combine whey and casein to provide immediate and longer lasting effects on muscle synthesis.

Which type of protein is best for protein shakes?

Different types of protein may affect your body in distinct ways.

For instance, whey is typically absorbed more quickly than casein. This makes it optimal for promoting muscle protein synthesis after exercise. It may also help you feel less hungry in the short term.

While some small studies have shown whey protein to be more effective for weight loss than soy and other plant-based proteins, others show no real difference.

As such, individual lifestyle factors may be more important than the type of protein regarding weight loss or other desired outcomes.

One key factor to consider is the quality of protein you purchase.

Whey, casein, and soy are considered complete proteins. This means they contain sufficient amounts of all the essential amino acids your body needs.

All the same, these three may induce an allergic reaction in some people. Rice and pea protein are often considered less allergenic. However, rice protein is low in the essential amino acid lysine. Pea protein is low in the essential amino acids cysteine and methionine.

Hemp protein is also considered less allergenic. Furthermore, it contains sufficient levels of all essential amino acids. As such, it can be considered a complete source of protein.

As long as you regularly consume a variety of protein sources, opting for incomplete proteins in your protein shake is unlikely to be a problem. That said, it’s always best to talk with a doctor or registered dietitian before adding new supplements to your diet.

Protein powders aren’t the only way to add additional protein to your shakes. Here are a few whole foods you can use in place of protein powder:

• Greek or plant-based yogurt: Greek yogurt is naturally rich in protein, as are plant-based alternatives made from soy. Each provides around 6–10 g of complete protein per 3.5 ounces (oz), or 100 g.
• Nuts and seeds: Most nuts and seeds pack around 5–7 g of protein per 1 oz (28 g). Combine with soy or hemp milk for a complete source of plant-based protein.
• Spirulina: This blue-green algae offers around 8 g of complete protein per 2 tablespoons (14 g). This serving also covers 95% of the Daily Value (DV) for copper and 22% of the DV for iron.
• Tofu: This popular soy food contains around 5–13 g of complete protein per 3.5 oz (100 g), depending on the variety. It has a naturally mild flavor, so you can blend it with frozen fruit and liquid to yield a protein-rich shake.
• Puffed quinoa: This pseudocereal provides around 10 g of complete protein per 2.5 oz (70 g). Expect it to thicken and add a slightly nutty flavor to your shake.
• Oats: This grain offers around 5 g of protein per 1.5 oz (40 g). Combine with cow’s milk or hemp milk to get a complete source of protein.

These protein-rich ingredients are an easy addition to homemade shakes. Simply combine them with your choice of dairy or plant-based milk, fruit, and leafy greens for a nutrient-rich, whole-food alternative to protein powder-based shakes.

The Food and Drug Administration (FDA) doesn’t typically review supplements for safety and effectiveness before they hit the shelves.

Thus, it’s important to research the ingredients in your protein powder and the brand’s trustworthiness. When possible, choose a protein that has undergone third-party testing.

Additionally, suggestions for serving sizes also vary by brand. Make sure to check nutrient labels to be sure you’re getting the amount of protein you desire.

If you’re lactose intolerant, drinking protein shakes made with whey or casein may cause side effects, such as:

• bloating
• cramps
• gas
• diarrhea

You can avoid these symptoms by switching to protein powders not derived from dairy, such as those made with protein from:

• eggs
• peas
• soy
• hemp

While most research suggests high protein diets are safe, people with underlying kidney issues may need to avoid them. If you have kidney complications, talk with your doctor before increasing your protein intake.

Most adults can easily get enough protein through food sources without drinking protein shakes. That said, protein shakes can be a delicious way to add extra protein to your diet.

If you’re trying to lose or manage weight, extra protein from shakes may help you feel less hungry.

It may also help you maintain muscle and metabolism and lower the likelihood of regaining lost fat, especially when combined with an exercise routine.