I’m not sure why anyone would want to consume JUST protein shakes, and nothing else.
As a nutrition coach, I certainly wouldn’t recommend it to any of my clients.
But as a thought experiment, could you actually survive on protein shakes?
Yes, you can survive on protein shakes alone, but you won’t optimize your health & fitness results, and you run the risk of experiencing nutrient deficiencies and digestive issues, especially if you try this beyond 1-2 weeks. In general, I recommend using protein shakes for a maximum of ⅓ of your daily protein intake.
So, while you can stay alive on protein shakes, you won’t be thriving.
- Your body has a way to use dietary protein as an energy source when it is not getting many carbohydrates so protein shakes can keep you alive.
- You run the risk of several negative side effects by drinking only protein shakes, including boredom, low energy, increased hunger, and digestive distress that can make you sick in the long-term.
- You can make protein shakes more nutritious by adding whole food ingredients like fruits, vegetables, nuts and seeds, and mixing with liquids other than water (I give you some examples below).
What Happens If You Just Drink Protein Shakes?
If you just drink protein shakes, and the only ingredients are protein powder and water, you will start missing out on both macronutrients (carbs and fat) and micronutrients (vitamins and minerals). Your body will start using protein to make glucose molecules (a form of sugar), but it has no way to make micronutrients.
If you use only protein powder and water, you will not be able to get the same intake of carbohydrates and fat as a regular mixed diet which includes a variety of whole foods.
Although your body can use protein for energy, carbohydrates are the body’s preferred source of energy, so you will likely have less energy than normal.
You will also not have fat as a source of energy, and you will not get essential fatty acids to help with skin and hair health, and regulation of hormones and blood pressure.
General dietary guidelines recommend a minimum of 20% of total daily calories come from fat because of the essential roles that they play in the body, including absorbing fat-soluble vitamins (A, D, E and K), balancing inflammation, and providing energy.
Your body will also not be getting the vitamins and minerals it needs for various aspects of your overall health.
I’ll cover the details of what this means in the next section.
Drawbacks Of Only Consuming Protein Shakes Every Day
If you only consume protein shakes every day, you can encounter several negative side effects, including:
Whole food sources of protein also include naturally-occurring micronutrients such as vitamins and minerals. If you only consume protein shakes, you are less likely to get the recommended amounts of these micronutrients, even if your protein shake has added vitamins and minerals.
Not all protein shakes have added vitamins and minerals, and those that do often have only the most common/popular vitamins and minerals added, whereas there are dozens of micronutrients.
Also, if you are not consuming dietary fat, you will not have a way to absorb the fat-soluble vitamins (A, D, E and K).
Micronutrient deficiencies can lead to decreased mental function, fatigue, lethargy, hair loss, and in more serious cases, blindness, and increased risks of other diseases.
Nutritional supplements like protein powder are not subject to the same FDA regulations as foods, which means that they are not tested to ensure that they only contain the ingredients stated, in the amounts stated. It’s possible for protein powders to include cheap filler ingredients that are not listed on the label.
These fillers are often starchy fibers to add bulk to the protein powder without actually adding protein. If they are even listed at all, they go by names like:
- Coconut flour
- Maltodextrin (corn sugar)
- Natural flavoring
- Prebiotic fiber
Drinking only protein shakes makes it more likely that you could be consuming these types of ingredients without even knowing it. These ingredients are frequently linked to digestive issues (covered in the next section).
Worse yet, your protein powder might contain a banned substance that is not allowed for your sport, which is a big deal if you are a competitive athlete.
Your best bet to ensure that you know exactly what you are getting is to buy a brand of protein powder that is third-party certified for purity and accuracy of the label.
If you only consume protein shakes, you can end up under-consuming fiber (or over-consuming it, if your protein powder has fiber as a filler ingredient), which can cause digestive issues like bloating, gas, constipation, or diarrhea. Other common ingredients like lactose & artificial sweeteners can cause these problems.
You might find that the amount of artificial sweetener in one scoop of protein powder doesn’t bother you, but if you consume protein shakes all day long, you get so much that you end up with painful stomach cramps.
- Can Protein Shakes Make You Nauseous? (Yes, Here’s Why)
- Protein Shakes & Diarrhea (Causes + Fixes Explained)
Rapid Weight Loss
Only consuming protein shakes can make it harder to get the same total calories as eating whole foods, partly because of the boredom of having the same thing all day. Rapid weight loss means losing more muscle mass and ending up with a lower metabolism than a slower rate of weight loss where more of the loss is fat.
At first, some people might be excited about the idea of losing weight quickly. However, rapid weight loss means that your body is more likely to start breaking down its own lean tissue (muscle) as a source of energy.
The end result is that you end up with a smaller, lighter body that has even less muscle mass than when you started, which means that your metabolism will be even lower and you will need to consume fewer calories than before just to maintain your weight.
It’s much better to pursue a small calorie deficit (10-20% lower than maintenance calories, the amount you need to maintain your current weight) so that weight loss will come mainly from excess body fat and not muscle.
You can preserve your lean muscle mass with adequate protein intake and resistance training as a signal to your body that it needs to keep its muscle.
- Related Article: How To Use Protein Shakes For Weight Loss? (A Helpful Guide)
When you consume only protein shakes, your carbohydrate intake is likely much lower (unless you have carbs in your powder, or mix it with a high-carb liquid like juice). It’s much harder for your body to create energy from protein. Without carbs as the body’s preferred source of energy, you’ll feel sluggish.
This is especially true in high-intensity settings where your body needs quick sources of energy like explosive weightlifting, sprinting, or other high-intensity workouts.
If you are only drinking protein shakes, you are more likely to feel hungry because drinking calories is less filling than chewing whole foods. Even though protein is the most satiating macronutrient, chewing and swallowing a chicken breast is more filling than drinking an equivalent amount of protein shake.
Feeling hungry all the time is not a pleasant sensation, even if you are trying to increase your intake for a calorie surplus, and especially if you are trying to decrease your intake for a calorie deficit.
Hunger and cravings also make it more likely that you will stop following your nutrition plan, and this can lead to episodes of binge eating.
If you only consume protein shakes as part of your nutrition plan, you are more likely to experience boredom because you are consuming the same thing for every meal, every day. Boredom will make it less likely that you will stick to the plan, which makes it less likely that you will get the results you are hoping for.
Even if you carefully planned your protein shakes to include added ingredients to make sure that you were getting all of the necessary micronutrients in the recommended amounts, and you made sure that your total calories and macros were sufficient for your needs, it would be hard to stick to this plan because of how boring and repetitive it would become.
- Related Article: Drinking Whey Protein Every Day (Are There Drawbacks?)
How Many Protein Shakes Should I Drink?
My recommendation is that no more than one-third of your total daily protein intake should come from protein powder. I also recommend that you combine your protein shakes with other foods to create balanced snacks or meals.
Before or after a workout, it is a good idea to combine a lean protein source like protein powder with a fast-digesting carbohydrate like a banana or white rice.
At a main meal away from your workout, you’d also want a slower-digesting source of complex carbohydrates, like potatoes or legumes, and a healthy fat like nuts, seeds, or avocado.
Even if you can’t or don’t want to combine whole foods with your protein shake (maybe you need a liquid diet for a health reason, or you have a busy schedule and you need to be able to drink your meals on the go), you can still add ingredients in the blender to make a balanced protein shake.
- 3 Protein Shakes A Day: Pros, Cons, & Should You Do It?
- 4 Protein Shakes A Day: Pros, Cons, & Should You Do It?
- Protein Shake Fast: What Is It + 6 Reasons NOT To Do One
Frequently Asked Questions
What Happens If You Only Drink Protein Shakes For A Week?
What happens if you only drink protein shakes for a week depends on whether you use only protein powder and water, or whether you make your shakes with additional ingredients that allow you to match your normal intake as far as macro and micronutrients. You are likely to feel hungrier and have less energy than normal.
In one week, you are unlikely to develop a dangerous deficiency in any one micronutrient, but you’re not likely going to feel your best, either.
If you’re only using protein power and water, it is also less likely that you will achieve the same total daily calorie intake. This would likely lead to weight loss, but you’d feel extremely hungry, too.
Can You Live Off Multivitamins and Protein Shakes?
Yes, you can survive off of multivitamins and protein shakes for many months, but you will not thrive. You will run the risk of micronutrient deficiencies, poor gut health from low fiber intake, and low energy. Overall, you will be in poorer health than getting the same nutrients from minimally processed whole foods.
Fromentin, C., Tomé, D., Nau, F., Flet, L., Luengo, C., Azzout-Marniche, D., Sanders, P., Fromentin, G., & Gaudichon, C. (2013). Dietary proteins contribute little to glucose production, even under optimal gluconeogenic conditions in healthy humans. Diabetes, 62(5), 1435–1442. https://doi.org/10.2337/db12-1208
Hannah Ritchie and Max Roser (2017) – “Micronutrient Deficiency”. Published online at OurWorldInData.org. Retrieved from: ‘https://ourworldindata.org/micronutrient-deficiency’ [Online Resource]
Ashtary-Larky, D., Ghanavati, M., Lamuchi-Deli, N., Payami, S. A., Alavi-Rad, S., Boustaninejad, M., Afrisham, R., Abbasnezhad, A., & Alipour, M. (2017). Rapid Weight Loss vs. Slow Weight Loss: Which is More Effective on Body Composition and Metabolic Risk Factors?. International journal of endocrinology and metabolism, 15(3), e13249. https://doi.org/10.5812/ijem.13249
About The Author
Lauren Graham is a Precision Nutrition Level 1 certified nutrition coach. She focuses on helping busy professionals balance healthy eating and purposeful movement. Lauren has a background in competitive swimming and is currently competing as a CrossFit athlete. She has a passion for training, teaching, and writing.
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