Do Protein Shakes Make You Fat Without Working Out?

In general, protein shakes do not make you gain weight without working out. Protein supplementation is popular not only for physically active people as a way to increase muscle protein synthesis. But also for the general public as a meal replacement and weight reduction component.

This means you can still use protein shakes, even when you don’t work out. But there are some consequences when you go overboard.

What Happens If You Drink Protein Shakes Without Working Out?

Generally, if you drink protein shakes without working out your body will break down protein into amino acids and use them for protein synthesis. However, chronically elevated levels of some amino acids can lead to insulin resistance by activating gluconeogenesis and persistent activation of mTOR.

People who get the most benefits from high-protein diets and protein shakes are typically physically active.

Some of the amino acids like BCAA (branched-chain amino acids) can be oxidized only in the skeletal muscles (source). That’s why drinking protein shakes after working out is recommended.

  • Resistance training opens the proverbial doors for amino acids to enter so they can be used to build muscle mass.
  • It enhances protein absorption in the muscle. This means when you work out, more amino acids will be used up to recover from the exercise, not just randomly circulate in the body.

This is good.

However, if there are too many amino acids in the body, and not enough resistance training been done, the doors are closed.

This means BCAA cannot enter into the muscle, so they will hang out in the liver and stimulate gluconeogenesis (glucose production).

A study done by Martina Goffredo from Yale University School of Medicine shows that elevated plasma amino acids including valine, isoleucine, tryptophan, and lysine are linked to hepatic and peripheral insulin resistance (source).

Does it mean you shouldn’t drink protein shakes when you don’t workout? Not exactly.

This means that for many people who are not working out, overconsuming protein shakes won’t provide any additional benefit. And in some cases, it might have a negative impact on health.

In summary: Protein supplementation should be used only if enough protein is not available in the normal diet. It should not be the staple part of the diet.

Do You Have To Work Out When Drinking Protein Shakes?

In general, you don’t have to work out when drinking protein shakes. Protein supplementation can be used for athletes, sportspeople, and lifestyle consumers as a part of a regular diet. Protein shakes are widely used as an ingredient in healthy cooking, smoothies, and meal replacements.

There are many ways to use protein shakes even when you don’t workout:

  • Mixing protein shake with fruits and veggies to create a smoothie
  • Adding protein shake to meals like breakfast cereals to increase total protein
  • Using protein powder to make cookies, brownies, or cakes
  • Using protein shake as a snack

In other words, you don’t need to be an athlete to drink protein shakes.


Please remember that the majority of scientific research done on protein shakes was performed on athletes or physically active individuals (source). This means that:

  • Gut microbiota
  • Fat oxidation
  • Protein metabolism
  • Insulin signalling
  • Glucose levels

And hundreds of other things will be totally different for sedentary versus physically active people.

In other words, just because protein shakes offer a laundry list of benefits for high-level athletes, it doesn’t mean they will have the same or even similar benefits for regular folks.

In summary: Moderation is the key. Protein consumption is a necessary part of daily diet as long as this consumption doesn’t exceed a person’s energy needs.

Can You Gain Weight By Just Drinking Protein Shakes?

In general, you can gain weight by just drinking protein shakes if your total energy consumption exceeds total daily energy expenditure. Regardless if you’re drinking protein shakes, eating fruits, or consuming only animal-based products, if you eat more than you burn, you will gain weight.

In other words, when you’re in calorie surplus, you will gain weight.

Doesn’t matter if you created a calorie surplus by eating protein, carbs, or fats. Any excess amount of calories consumed is gonna be converted into fat.

When Should I Drink Protein Shakes For Weight Loss?

The best time to drink protein shakes for weight loss is after physical activity. Drinking a protein shake after working out enhance muscle protein synthesis, inhibits muscle protein breakdown, increases energy expenditure, lowers the appetite, and can lead to higher lean body mass.

Actually, there are two best time to consume protein shakes. During and after workout.

  • During workout

During the exercise, there is microscopic damage done to the muscle tissue which increases muscle protein breakdown. Having a protein shake during the workout helps to send those amino acids to where they belong, start to repair the damage, and stimulate protein synthesis (source).

  • After workout

Resistance training in itself creates an opportunity to build muscle by repairing the damaged tissue. And the rate of protein absorption by the muscle is much greater after a workout.

Will Protein Make Me Gain Weight If I Don’t Work Out?

As a whole, protein won’t make you gain weight if you don’t work out. Proteins should be part of the regular diet, and it is recommended to consume a minimum of 0.8 grams of protein per kg of body weight for sedentary people and 1.5 grams of protein for physically active people.

Related article: Can You Gain Fat On A Calorie Deficit?

Can I Lose Weight Without Protein Shakes?

Generally, you can lose weight without protein shakes. Weight loss depends on calorie deficit only, regardless of the macronutrients or diet methods. Protein shakes can enhance daily protein intake in times of low protein availability, but they are not the predictor of weight loss.


In summary, protein shakes won’t make you gain weight even without the exercise as long as you take it easy and don’t live on shakes. It may feel logical that if high-protein diets offer weight loss, then eating mainly shakes will give even better results.

But that’s not the case.

I love protein shakes to use as a base of cookies or brownies, or even smoothies. But it is important to highlight that shakes should be used on occasion, and preferably in the times when you just don’t have any access to regular food.

Michal Sieroslawski

Michal is an exercise physiologist (MSc) and a veteran endurance athlete. He loves to experiment and share his successes and failures to help busy men and women who want to lose weight.

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