There is some evidence that consuming protein can help a person lose weight, and there is clear evidence that it can help people build muscle mass if they also exercise.
However, research, as yet, does not make it unclear when is the best time to have protein. It is also unclear if there is any best time at all, why this is the case, or whether it is the case for everyone.
Most people in the United States get enough protein in their diet. Still, the United States Department of Agriculture (USDA) say many people should vary the types of food containing protein that they eat.
If a person is trying to build muscle mass, they may also take protein in the form of supplements to help them build muscle tissue after exercise.
When you are trying to lose weight
Protein is essential for building muscle and may aid weight loss.
There is some evidence that eating protein can help a person lose weight.
Evidence suggests protein does this in part by increasing satiety. Satiety is the feeling of being full.
Currently, there is little solid evidence regarding when the best time to eat protein might be to encourage weight loss.
For example, researchers published a study in the journal Advances in Nutrition suggesting that eating snacks that contain protein may reduce the number of calories a person consumes at their next meal.
However, the research paper also points out that studies demonstrating this are scarce and sometimes conflicting. They suggest more studies are needed to confirm their findings. This was also the conclusion of a study in the Journal of the Academy of Nutrition and Dietetics.
In contrast, a study in the American Journal of Clinical Nutrition suggests that a diet generally higher in protein can improve body weight management. The classification of higher protein in the study was 1.2 to 1.6 grams of protein per kilogram of body weight per day.
Research is still evolving about the relationship between protein and weight loss, including when is the best time to eat protein for this purpose.
When you are trying to build muscle
Various studies have looked at whether there is a link between the time a person consumes protein and hypertrophy, which is how much muscle a person builds after exercise. However, the results are unclear.
Two studies in the International Journal of Sport Nutrition and Exercise Metabolism and the Journal of the International Society of Sports Nutrition suggest there is no relationship between building muscle and the timing of consuming protein.
More research is necessary to establish if there is a link between the timing of protein intake and the amount of muscle a person builds.
A small, older study in the Journal of Physiology found that skeletal muscle grew in older adult males who took a protein supplement soon after exercise.
A recent meta-analysis in the Journal of the International Society of Sports Nutrition suggests that while evidence is conflicting about the best time to consume protein after exercising, if athletes eat protein soon after working out, they are more likely to consume enough protein over the course of a day to build their muscles.
The researchers conclude that there are no known downsides to eating protein before or after a workout. Also, if that helps an athlete get sufficient nutrients for their body to recover, then there is no issue.
The most explicit message from current research is that if a person wants to build muscle, then consuming enough protein is more important than the timing of when they consume the protein.
Importantly, many of these studies assume that the person consuming the protein is an athlete doing many hours of intense exercise a week. For the average person, what is necessary is that they consume a balanced diet, supplementing this with more protein than usual if they are focusing their exercise on building muscle.
Research shows that increasing the amount of protein in a person's diet is good for better weight management and is important for building muscle mass after exercise. However, research has not yet been able to determine when the best time to consume protein might be or if there is any best time.
For professional athletes, where marginal differences in muscle development may result in small but significant performance improvements, experimenting with different times to have protein may be worthwhile to achieve their goals.
For most people, however, what is essential is that a person consumes enough protein to keep them in good overall health as part of their everyday, balanced diet.