Should You Take Protein Powder on Rest Days? Here's What to Know

The day to day routine doesn’t change much.  Wake up, work, train, eat, do it again.

Whether you’re a guy or girl reading this, you resistance train to gain strength, build some muscle and improve your body composition.

If you’re not, you should be!

On training days, you have likely come across the recommendation to fuel recovery with essential amino acids and high-quality protein. But what about the days you do not lift? Should you drink protein shakes on rest days, or skip the shake when you are off?

Based on the research, the answer is yes, and we'll provide a compelling rationale.

Should You Take Protein Powder on Rest Days?

Yes. Your body is in a constant state of flux between building and breaking down proteins all throughout your body, not just in your muscles, but also in your bones, liver, skin, tendons, ligaments, and lungs.

For this reason, an adequate delivery of protein is important each day, as is delivery of the essential amino acids, which you can get from animal-based protein sources like beef, poultry, milk, and eggs.

You have likely read several times over that on the days you train a key step to promoting maximal recovery and stimulating increases in muscle strength and growth is to take a daily dose of the essential amino acids.

Studies have shown that around 6 – 12 grams of the key amino acids are what is needed to maximally stimulate growth (1).

Other studies have shown that a high-quality protein source like whey protein isolate, which contains the highest concentration of the essential amino acids of all protein sources, does a great job at stimulating increases in protein growth (4).

A typical 25 gram dose of whey protein isolate delivers the upper end of the required amino acids, and works best as one larger dose rather than several smaller ones (5).

So how does this carry over to rest days? A study by Burd (2) helped shed light on the question. Fifteen young men completed a resistance training bout, then returned the next morning (a rest day) and consumed a shake containing 15 grams of whey protein isolate. 

Measures of muscle protein synthesis showed that a single bout of resistance exercise provides a stimulatory effect on muscle proteins for up to 24 hours after the workout, well beyond the five-hour window previously reported (3).

The proteins responsible for contracting and shortening muscle tissue were stimulated to an even greater degree, suggesting that proteins involved in the exercise process experience specific and favorable changes the day after training (2).

Practically speaking, a protein shake on a rest day, particularly the day after a workout, may stimulate protein growth to a greater extent than would occur without a preceding training session. The finding has real world relevance whether you are traveling, missing a couple of sessions, or taking a planned recovery day.

While strong arguments could be made to suggest a whey protein isolate is a preferred source of protein because of its higher concentration of essential amino acids than other protein sources, these study findings should not lead someone to think they have to consume whey protein for this to work as its possible other protein sources may also have a similar impact.

Total Daily Protein Matters More Than Timing

While fueling around your training sessions is well established, research suggests total daily protein intake is the larger driver of long-term changes in muscle mass and body composition. From a practical standpoint, a protein shake on a rest day is not wasted. It is helping you reach your daily protein target, which is what matters most.

Most research suggests a daily intake of 0.7 to 1 gram of protein per pound of bodyweight, with the appropriate amount depending on your goal:

• Bulking: Lean toward the higher end to support muscle growth and recovery.
• Cutting: Maintain or slightly increase intake to preserve lean muscle while in a calorie deficit.
• Maintenance: The middle of the range tends to be sufficient for day-to-day recovery.

If your schedule, appetite, or training load makes it difficult to reach this number with whole food alone,  protein powder is one of the simplest ways to close the gap.

Whole Food Protein Sources Still Matter

Protein powders are best used as a tool rather than a replacement. Whole food sources such as beef, poultry, eggs, dairy, fish, and legumes provide protein along with vitamins, minerals, and fiber that supplements do not deliver. A protein shake is best used to help reach your daily target when whole food is harder to come by, not to replace meals altogether.

What Type of Protein Powder Is Best on Rest Days?

Different proteins fit different rest day needs:

• Whey Protein Isolate (Phormula-1): Digests fast and delivers the highest concentration of essential amino acids. Ideal post-workout and great any time.
• Casein: Digests slowly, providing a steady release of amino acids. Good before bed or between meals.
• Plant-Based Blends (pea, rice): Work well for those who avoid dairy.

If you're a runner, see our guide on the best protein powder for runners. If you're trying to add size, our breakdown of protein powder for weight gain is a good next step.

Common Rest Day Protein Myths

• Myth: The anabolic window means a rest day shake is wasted. Research has shown that muscle protein synthesis remains elevated for up to 24 hours, and possibly longer, following a single bout of resistance exercise.
• Myth: Protein powder causes fat gain. Fat gain is the result of consuming more total calories than your body uses, not any one specific food or supplement.
• Myth: Protein only matters on training days. Your body is in a constant state of building and breaking down protein regardless of whether you trained that day.
• Taking Protein Powder on Rest Days Has Important Benefits

The benefits of resistance exercise extend well past the three to five hours commonly discussed. Recent findings suggest that delivering a small dose of high-quality whey protein the day after a workout supports greater muscle protein growth than would otherwise be expected.

Studies show that the combination of regular resistance exercise and high-quality whey protein ingestion confers favorable advantages for individuals who hope to increase strength, lean muscle mass, and improve their body composition.

If you are looking for a clean, fast-digesting whey protein isolate to support both your training and rest days,  shop Phormula-1.

Frequently Asked Questions

How much protein should I take on rest days?

Aim for the same daily target you hit on training days, typically 0.7 to 1 gram per pound of bodyweight.

When is the best time to drink a protein shake on a rest day?

Any time works. Many people prefer one between meals or before bed to keep amino acids steady throughout the day.

Should I drink protein shakes before or after workouts on training days?

Both can work. See our guide on protein before or after workout to pick the timing that fits your routine.

Can I mix creatine with my protein powder?

Yes. Mixing creatine with protein powder is a convenient way to take both at once.

Will I gain fat if I take protein powder on rest days?

No. Fat gain is driven by total calorie intake, not by adding a protein shake. If you keep your calories aligned with your goal, a rest day shake will not add body fat.

Is one shake enough on rest days?

One shake plus whole food protein sources is usually plenty to hit your daily target.

References:

1. Borsheim, E., K. D. Tipton, et al. (2002). “Essential amino acids and muscle protein recovery from resistance exercise.” Am J Physiol Endocrinol Metab 283(4): E648-657.

2. Burd, N. A., D. W. West, et al. (2011). “Enhanced amino acid sensitivity of myofibrillar protein synthesis persists for up to 24 h after resistance exercise in young men.” The Journal of nutrition 141(4): 568-573.

3. Moore, D. R., J. E. Tang, et al. (2009). “Differential stimulation of myofibrillar and sarcoplasmic protein synthesis with protein ingestion at rest and after resistance exercise.” J Physiol 587(Pt 4): 897-904.

4. Tang, J. E., D. R. Moore, et al. (2009). “Ingestion of whey hydrolysate, casein, or soy protein isolate: effects on mixed muscle protein synthesis at rest and following resistance exercise in young men.” J Appl Physiol 107(3): 987-992.

5. West, D. W., N. A. Burd, et al. (2011). “Rapid aminoacidemia enhances myofibrillar protein synthesis and anabolic intramuscular signaling responses after resistance exercise.” The American journal of clinical nutrition 94(3): 795-803.