Seize the Time: Reconsidering Fast and Slow Digest Protein


Good news: Protein timing may not be as critical as you think it is. A handful of new studies suggest protein timing may only be important if you’re an elite athlete or someone who trains intensely, multiple times daily. Here’s the rundown on protein timing for everyday fitness buffs and weekend warriors like you.

Rapid Recovery

Conventional sports nutrition wisdom says you should slam down carbs and protein immediately after your workout to maximize gains. Carbs and protein replenish your muscle glycogen, stimulate muscle protein synthesis and spike your insulin to enhance nutrient uptake.

Surprisingly, research suggests you may be better off exercising without consistently replenishing glycogen via post-workout carbs, especially if lean muscle or weight loss are your goals. One study implies that consistent post-workout carb ingestion may cancel out benefits gleaned from the actual workout.

Carbs, of course, are an excellent way to improve absorption and digestion of protein. However, if you’re not ingesting post-workout carbs, do you still need post-workout protein and vice versa? Not necessarily.

Muscle Protein Synthesis

The theory goes that consuming protein after your workout capitalizes most effectively on your body’s unique anabolic window. This window is the time frame within which your body is most susceptible to nutrients and the rapid use of nutrients for Muscle Protein Synthesis (MPS).

Yes, it’s true that your body replenishes glycogen faster when you consume protein and carbs within 30 to 60 minutes of your workout. It’s also true that consuming protein and carbs at any time after your daily workout is equally effective. It’s more important to focus on your total daily protein intake, which should be at least 0.8 to 2 grams per pound of body weight.

What’s the Point of Fast or Slow Digest Protein

In the 1990s heyday of sports nutrition, when Rodney Coleman reigned and Hydroxycut became a household name, supplement companies championed fast and slow digest protein products. The idea is that you reserve fast digest for post-workout, when your body is broken down, extra hungry and in need of protein/carbs rapidly.

Another theory holds that slow digest is best suited for pre-workout and breakfast shakes. The slower digest protein breaks down gradually, keeping your blood glucose stable and your muscles fueled over a longer period. Slow digest protein products were also marketed as overnight proteins to take before bed, presumably to keep slowly feeding your muscles as you sleep.

With new evidence suggesting timing is irrelevant, what value are slow and fast digest proteins? Slow and fast digest proteins are still crucial to elite athletes and people who train several times daily at high intensity levels.

Elite fitness activity and frequent, intense workouts stress your body to higher degrees. The higher degree of stress requires more high quality fuel. Your consistently broken-down muscles must have the building blocks for proper recovery.

How to Use Fast and Slow Digest Protein

If you’re not an elite athlete or an athlete who works out multiple times daily, focus on fulfilling your total daily needs for protein, carbs, nutrients, other critical macros and micros. Providing you do this, you can break up the intake into as many meals as you prefer and eat each meal when it’s convenient and sensible for you.

At the same time, you can still use slow and fast digest proteins to complement a busy schedule or a customized diet cycle strategy, such as intermittent fasting. For those days when you can’t prep a meal and must rush to the gym, grab a fast digest protein like whey. When restricting calories and subsisting on less, guzzle a slow digest protein to kill hunger for longer periods between solid meals.