A protein shake diet encourages weight loss by curbing appetite and reducing the total calories consumed. While these diets can be effective in the short term, it is unwise to live solely or primarily on meal replacement shakes.

Protein helps build muscle and plays a role in almost everything the cells in the body do.

Protein needs will vary from person to person based on weight and activity level, but most people need at least 50 grams of protein per day. This amount can easily be met by consuming beans, lentils, nuts, meat, eggs, and dairy products.

Protein shakes aim to provide, as much or more protein, as ordinary food, but with fewer calories. The idea is that weight loss and muscle gain are improved, as a result.

Fast facts on the protein shake diet:

  • Most protein shake diets encourage the use of meal replacement protein shakes.
  • A protein shake diet requires eating at least one protein shake per day.
  • The primary risk of a protein shake diet is when protein shakes are the only source of food.
  • Anyone choosing to try a protein shake diet should check the protein source and other ingredients.

protein shake powder on a spoon and made in a glassShare on Pinterest
Protein shakes may offer as much protein as food, but with less calories.

Protein shakes offer more than just protein. They are typically fortified with a range of vitamins and minerals, and may also contain fruits, vegetables, and other nutrients.

Research has linked protein consumption to increased feelings of fullness. Thus, people who include enough protein in their diets, including from protein shakes if they choose, may have fewer food cravings and, so, eat less.

Health benefits of protein

Most protein-rich foods are high in a variety of vitamins and minerals. Some of these nutrients, such as B-complex vitamins, iron, choline, and zinc, are difficult to get in adequate quantities from other sources.

Other vital nutrients that are plentiful in some protein-rich foods include:

How does protein work in the body?

Protein supports numerous vital functions of the body, including building and repairing:

  • bones
  • muscles
  • skin

Protein also helps the body create hormones and enzymes and metabolize vitamins. It is an essential part of a well-balanced and nutrient-dense diet that encourages good health.

What can you eat on a protein shake diet?

A variety of companies offer protein shake-based diets. So the requirements and offerings of each program vary. Some diets are more extreme, encouraging participants to eat only or primarily protein shakes.

The most balanced protein shake diets include protein shakes, as only part of a diet that is rich in other food sources. For instance, the diet might recommend replacing one to two meals with a protein shake, then eating one to two different meals that are also healthful, and one to two snacks.

A well-balanced diet should always include an appropriate amount of protein, nutrient dense carbohydrates, and healthy fats.

A variety of sweetenersShare on Pinterest
Sweeteners may be used in protein shakes to improve the flavour.

Meal replacement shakes are not intended to replace healthy, balanced diets. It is difficult, and perhaps even impossible, to get every nutrient from a single food source.

Furthermore, a body starved of nutrients may experience problems with metabolism, slowing or completely thwarting weight loss. A 2015 study found that people who eat a varied diet are less likely to be obese.

Some protein shakes use lots of sweetener to improve flavor, which can trigger blood sugar spikes. Protein shakes that use sugar alternatives may be more difficult for the body to metabolize. Some people experience negative reactions, such as nausea, vomiting, bloat, and gas.

A Consumer Reports analysis also found that some protein drinks have unsafe levels of contaminants. Three of the drinks tested by the consumer watchdog had high levels of contaminants such as:

  • mercury
  • arsenic
  • cadmium

Consumers who drink three servings of these drinks each day could suffer serious health consequences.

Contaminants are just one more reason why relying on protein shakes, as a sole source of nutrition, can be unsafe.

In an additional eight of the drinks tested by Consumer Reports, levels of lead were high enough to need a consumer warning in California.

Because protein shakes are treated as nutritional supplements, they are subject to fewer regulations than medication is in the United States. Marketing materials for these products, Consumer Reports argues, may also be misleading.

The organization recommends eating protein-rich foods, such as milk, lean meats, and eggs instead of protein shakes.

Share on Pinterest
It is recommended to speak to a doctor or registered dietitian, to safely implement a protein shake diet.

Protein consists of amino acids, and the best proteins are "complete," which means they contain all nine essential amino acids. Most protein shakes use one or a combination of the following six varieties:

  • whey protein
  • casein protein
  • egg white protein
  • soy protein
  • plant protein
  • beef protein

To get the most out of a protein shake diet, talk to a doctor or registered dietitian first. Then consume protein shakes only on a short-term basis.

A person should stick to 1-2 protein shakes per day, and choose those that complement a healthful diet.

For instance, a person who does not get many vegetables in their diet might choose a meal replacement protein shake that contains vegetables.

To maximize weight loss, eat nutrient-dense, low-calorie foods in between protein shake meals. Eggs, lean meat, lentils, fruits, and vegetables are excellent ways to round out a protein shake diet.