Whey vs. Food: Which Is Best for Muscle Protein Synthesis

Myofibrillar Protein Synthesis Key Points

• Whey Protein rapidly stimulates muscle protein synthesis, but the effects are short-lived.
• Whole foods result in much longer increases in muscle protein synthesis compared to whey protein.
• Whole foods contain added vitamins, minerals, and cholesterol which can increase muscle protein synthesis and increase anabolic signaling pathways.

Introduction

In the world of fitness and bodybuilding, muscle protein synthesis (MPS) is paramount for training-induced muscle hypertrophy, as it is the process by which new proteins repair and grow muscle tissue. There is an ongoing debate on whether whey protein supplements or whole foods are more effective in promoting MPS. 

Muscle Protein Synthesis and Amino Acids

MPS is a vital process for skeletal muscle mass, repair, and maintenance. It is highly dependent on the availability of amino acids, particularly the essential amino acids (EAAs), which the human body cannot synthesize. (Wolfe, 2017) Skeletal muscle contributes 25-30% of the whole-body protein synthesis in the body. (Nair et al., 1988) Bodybuilders have put branched-chain amino acids (BCAAs: Leucine, Isoleucine, and Valine) into their workout shakes for years in order to increase the anabolic signaling pathways of resistance exercise. 

Leucine, Insulin, and Whole-Body Protein Synthesis

Leucine, an EAA, has been found to play a central role in the stimulation of MPS by activating the mammalian target of rapamycin (mTOR) signaling pathway. (Duan et al., 2016) When training to gain mass, it’s essential to be in a positive nitrogen balance. Nitrogen balance, which reflects the balance between protein intake and protein breakdown, is important in maintaining muscle mass and promoting myofibrillar protein synthesis. (Golden et al., 1977) 

A study by (Churchward-Venne et al., 2012) investigated the role of leucine, an essential amino acid, in regulating human myofibrillar protein synthesis. The study found that supplementing a suboptimal protein dose with leucine or essential amino acids did increase MPS rates at rest and following resistance exercise in men. However, the increase in MPS rates was not sustained over a prolonged period, suggesting that plasma EAAs alone may not be sufficient for promoting long-term gains. Thus, high-quality protein from whole foods is needed in conjunction with supplemental amino acids for optimal human skeletal muscle protein synthesis.

On the other hand, whole foods contain a complex mixture of amino acids and other nutrients such as vitamins, minerals, and fiber. This nutrient complexity may be important for promoting long-term myofibrillar protein synthesis.

The Impact of Fasting on MPS

Fasting, or voluntary abstinence from food intake for extended periods, has been shown to influence protein metabolism, favoring muscle tissue breakdown. During fasting, insulin levels decline, and the body shifts to a catabolic state, breaking down stored nutrients (i.e., body fat and glycogen), including muscle proteins, to provide energy and maintain blood glucose levels.

This can lead to increased protein breakdown and a negative nitrogen balance, which, if prolonged, can result in atrophy and reduced muscle strength. However, research suggests that intermittent fasting, or fasting for shorter periods followed by periods of normal eating, may not have detrimental effects on muscle mass and may even promote myofibrillar protein synthesis when combined with resistance training and adequate protein intake during feeding periods. (Keenan et al., 2020) If you adhere to an intermittent fasting protocol, it may be beneficial to consume essential amino acids while in a fasted state to improve body composition.

Does More Protein Ingestion Increase Muscle Mass?

The RDA for protein intake for men and women is .8 g/kg/bw or .4 grams per pound of body weight. The RDA protein requirements were never meant to be used for athletes or those wanting to build muscle. 

If you want to build size, you should be looking for protein intake to stimulate maximal muscle protein synthesis, not optimal. There is a difference. For example, plant-based protein can stimulate protein synthesis, but animal-based products will lead to a maximal increase in protein synthesis. (Mathai et al., 2017) For perspective, 2-ounce beef or peanut butter equivalents yield .18 g protein and .8 g protein, respectively.

Adequate protein intake is essential for promoting muscle mass and reducing muscle protein breakdown (MPB). Studies have shown that protein consumption of 1.8 to 2.0 grams per kilogram of body weight (.9 grams per pound of body weight) per day is optimal for promoting muscle hypertrophy and maintaining lean body mass in both young and older adults. (Stark et al., 2012). Although strength training, athletes should opt for the higher side of protein. 

Muscle Protein Breakdown and Resistance Exercise

While resistance exercise is well-known for its ability to stimulate myofibrillar protein synthesis, it also induces muscle protein breakdown during the early stages of recovery. However, the increase in muscle protein breakdown is typically outweighed by the rise in muscle protein synthesis, resulting in a net positive protein balance and muscle growth over time. (Phillips & Van Loon, 2011) Consuming protein before or after resistance exercise such as whey or casein can help attenuate muscle protein breakdown and enhance the anabolic response. (Tipton et al., 2001)

Untrained Athletes have greater increases in protein synthesis after resistance exercise than trained athletes.

Nutrition, Caloric Intake, and Hypertrophy

Muscle growth requires adequate protein intake and sufficient caloric intake to support the energy demands of muscle protein synthesis and muscle function. (Morton et al., 2018) In conjunction with resistance training and adequate protein consumption, a caloric surplus can promote muscle hypertrophy and strength gains.  Many people seeking muscle gain often resort to protein supplements to increase muscle. However, this may not be optimal for myofibrillar protein synthesis.

Whole Foods vs. Whey Protein for Stimulating MPS

Whole foods contain protein, vitamins, fats, and other nutrients (i.e., cholesterol) that can increase muscle protein synthesis and anabolism.  Here are a few studies to consider:

• Despite an equal amount of protein, whole milk stimulated greater protein synthesis than skim milk. (ELLIOT et al., 2006)
• Whole eggs stimulated greater protein synthesis than egg whites despite an equal amount of protein. (van Vliet et al., 2017)

Whey protein results in a rapid increase in protein synthesis. Muscle protein synthesis rates increase rapidly after ingesting whey protein, typically within 1-3 hours after consumption. (MacDougall et al., 1995) This rapid increase in muscle protein synthesis results in the muscle full effect. (Pennings et al., 2012) This means that muscle protein synthesis is rapidly increased.

The exact time frame may vary depending on factors such as the dose of whey protein consumed, the individual’s age and fitness level, and whether or not the whey protein is consumed in conjunction with exercise. However, it is generally believed that the anabolic effects of whey protein consumption are relatively short-lived and that muscle protein synthesis rates will return to baseline levels within a few hours after consumption.