People take protein supplements for different reasons. Protein powders like whey protein have been shown to promote muscle growth and improve recovery, and they may even help with satiety and weight loss, according to July 2017 research in Nutrients.
But when it comes to protein powder and protein shakes, you might be wondering how much is too much. Whether you prefer whey protein powder or are into plant-based varieties, too much of anything (even so-called "healthy" foods) can be a bad thing. Read on to find out what happens if you drink too much protein.
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When you take too much protein powder, the excess is excreted in urine or stored as glycogen and fat. That said, drinking two protein shakes a day is likely safe for most people.
But even though they're considered "healthy," drinking too many protein shakes may cause you to take in too many calories and sugar, leading to weight gain and other health problems. Swapping meals with protein shakes can also cause nutrient deficiencies.
Unless directed otherwise by a doctor or dietitian, a high-protein diet is not recommended for people with existing liver or kidney problems as it may worsen their symptoms.
How Much Protein Do You Need?
People often think that when it comes to certain nutrients, more is better. Using supplements to get mega-doses of nutrients hasn't been shown to provide additional benefits; and in most cases, people can get everything they need through whole foods.
The recommended dietary intake (RDI) set by the Food and Nutrition Board of the National Academies of Medicine is 46 grams of protein for people assigned female at birth (AFAB) and 56 grams for people assigned male at birth (AMAB).
That means it's probably safe for you to drink two protein shakes a day and no more than three protein shakes per day, depending on how much protein is in your powder.
Those recommendations are based on an estimate of .8 grams of protein per kilogram of body weight. So, a 150-pound person needs about 55 grams of protein daily whereas if you weigh 190 pounds, your protein needs will be higher than the RDI — 69 grams.
There may be a benefit to getting more protein if you have are very active and/or have specific goals such as building muscle or losing weight. Recreational athletes need between 1.2 and 2 grams of protein per kilogram of body weight, according to the Academy of Nutrition and Dietetics and the International Society of Sports Nutrition (ISSN).
Effects of Drinking Too Much Protein
Drinking too much protein through protein shakes can have negative side effects. There aren't many specific differences among the types of protein powder if you drink too much, though milk-derived supplements may cause digestive issues.
Excess protein is excreted through your urine, so there's little danger in getting too much of the nutrient. That said, drinking too many protein shakes comes with other risks.
Many of the commercial protein shakes on the market and the ones you can buy at smoothie bars have high amounts of added sugar. For example, 12 ounces of one commercial protein shake has 30 grams of sugar — more than the amount in a can of soda — per the USDA.
Too much sugar in your diet can lead to and worsen a whole slew of health problems, such as obesity, heart disease and type 2 diabetes, per the Mayo Clinic.
It's true that getting enough protein can help with weight loss and may improve body composition. It helps keep you full for longer, promotes lean muscle growth and supports your metabolism. But drinking too much protein in shakes can have the opposite effect.
Even if you're putting in time at the gym and need a lot of extra protein, taking in more calories than you need can lead to weight gain. While protein in any form may aid weight loss due to its effects on appetite and satiety, taking in more calories than you're burning will still lead to weight gain.
In addition, protein shakes may not be your best bet for increasing protein intake when trying to lose weight. Liquid calories have less of an effect on satiety than calories from solid foods, according to a review published in February 2015 in Trends in Food Science & Technology. For extra protein, you may be better off eating a chicken breast than drinking protein shakes.
It's possible that drinking too many protein shakes may lead to dehydration, according to April 2002 article in University of Connecticut Advance. During the study, researchers observed that after adopting a high-protein diet, athletes showed signs of dehydration despite drinking the same amount of water as when eating a moderate-protein diet.
The researchers say this is a key finding, as the kidneys require more fluids in order to flush excess protein from the body. Also worth noting, the athletes in the study didn't feel thirstier despite the increased need for fluids.
The researchers say non-athletes and athletes should both drink more water when increasing protein in the diet to reduce the risk of dehydration.
Some people swap out meals with protein shakes to help with weight loss or just to be healthier in general — but this might not be the best strategy.
Protein shakes may be high in protein, but they typically lack other important nutrients such as complex carbohydrates, healthy fats and fiber. Eating meals that are balanced with a variety of nutrients helps to support all of your body's functions.
If you're using protein shakes as a meal replacement, you'll have to be diligent about getting enough of your key nutrients at other meals to avoid deficiencies.
If you're drinking a protein shake twice a day or more, you may wonder how safe it is for your kidneys. There are many rumors about how protein powder affects the kidneys, but the truth is that it doesn't seem to negatively affect renal function in people with healthy kidneys, per July 2015 research in The American Journal of Clinical Nutrition.
Excess protein, though, can be harmful to those with chronic kidney disease, according to January 2017 research in the journal Current Opinion in Clinical Nutrition and Metabolic Health. Researchers suggest that drinking too much protein in shakes may worsen this condition.
Tammy Sanders, RD, LDN, CDE, at DaVita®, a dialysis clinic chain, recommends that dialysis patients use one scoop of protein powders such as whey protein per day. They can add some to their morning coffee as well as to low-potassium fruit juices and homemade desserts. Depending on the brand, one scoop delivers about 10 to 50 grams of protein.
Contrary to popular belief, whey protein won't damage your liver. You've probably heard of elite athletes who developed liver disease or died from cirrhosis, but that's likely due to their use of anabolic steroids, which cause hepatotoxicity, according to a March 2018 review in Current Sports Medicine Reports.
Too much protein, though, can worsen existing liver diseases, such as cirrhosis and hepatic encephalopathy. Dietary protein increases ammonia concentrations, which in turn, may affect hepatic function in people with liver problems, according to June 2015 research in the American Journal of Renal Physiology.
Excess protein may worsen hepatic encephalopathy symptoms in up to 35 percent of cirrhotics. Furthermore, one-third of those who have this disease are protein intolerant, according to a December 2014 study in Hepatology International.
If you have liver problems, consult your doctor before taking whey protein powder or other protein supplements.
The Bottom Line
Even athletes can get all the protein they need from whole foods without drinking protein shakes, according to the Academy of Nutrition and Dietetics. While protein shakes are convenient, they should not be your main source of the nutrient.
Filling up on shakes can cause you to take in too many calories, and it can also keep you from eating other foods that offer essential nutrients like dietary fiber and healthy fats.
If you want to include a protein shake in your daily diet, start with one scoop of protein powder per day. Choose a high-quality protein powder without added sugar, then get the rest from sources of protein like fish, chicken, nuts and beans.
- MDPI: Nutrients: Effects of Whey, Soy or Leucine Supplementation With 12 Weeks of Resistance Training on Strength, Body Composition, and Skeletal Muscle and Adipose Tissue Histological Attributes in College-Aged Males
- Examine: Does High-Protein Intake Help When Dieting?
- Springer Link: Obesity Surgery: Whey Protein Supplementation Enhances Body Fat and Weight Loss in Women Long After Bariatric Surgery
- ScienceDirect: Nutrients in Dairy and their Implications on Health and Disease: Chapter 16 - Lactose Intolerance
- NIH: U.S. National Library of Medicine: Genetics Home Reference: Lactose Intolerance
- Johns Hopkins Medicine: Lactose Intolerance
- ScienceDirect: Nutrition: Dietary Protein Intake and Change in Estimated GFR in the Cardiovascular Health Study
- Current Opinion in Clinical Nutrition and Metabolic Health: Dietary Protein Intake and Chronic Kidney Disease
- DaVita: Whey Protein Powder and the Dialysis Diet
- NCBI: Hepatology International: Protein Restriction in Hepatic Encephalopathy Is Appropriate for Selected Patients
- Today's Dietician: High-Protein Diets and Weight Loss
- USDA: National Agricultural Library: How Many Calories Are in One Gram of Fat, Carbohydrate, or Protein?
- USDA: National Nutrient Database for Standard Reference Legacy Release: Whey Protein Powder Isolate
- AARP: Healthy Living: How Much Protein Do You Need After 50?
- Royal Society of Chemistry: Dietary Protein Intake and Human Health
- Albion Alumni: Proteins
- NCBI: Nutrition & Metabolism: A High-Protein Diet for Reducing Body Fat: Mechanisms and Possible Caveats
- Mayo Clinic: Added Sugar
- University of Connecticut Advance: Too Much Protein Causes Dehydration