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One of the most common reasons people work out is to build muscle. They desire a trimmer physique or want those six-pack abs. Engaging in the right exercises helps achieve this fitness goal. So too does eating the right foods.
Typically, this involves giving clients advice about what to eat on training days. Pre-workout diet suggestions ensure their body has enough fuel to support the increased physical activity. Post-workout nutrition is also important as it aids in muscle recovery.
But one area of diet that is sometimes left out of these discussions is what to eat on rest days.
Some clients believe muscle recovery only occurs on workout days. Yet, muscle repair takes place up to 48 hours post-workout. Eating the right foods to support this repair ensures the muscles have the nutrients they need to grow.
Research also reveals that nutrition is important for reducing workout-related muscle soreness. This soreness can impact range of motion, in addition to causing discomfort. Consuming the right nutrients helps by influencing the body's inflammatory response. (1)
If you know you're not going to exercise today, intuition says to reduce your calorie intake. Since you're not going to expend as much energy, you don't need to eat as much. Is this true? Should you eat less on rest days when trying to gain muscle?
Some fitness professionals say that fewer calories are needed because you're not as active. Others feel your caloric intake should remain the same as training days to help the muscles grow. Who is right?
The answer to this question depends, in part, on your client's goal. If they want weight loss along with muscle growth, reducing calories on rest days can help. The body does still needs nutrients to aid in recovery. As long as these needs are met, calories can be lowered slightly.
If the client only wants to build muscle, it may make more sense to keep calorie intake relatively the same. This ensures they'll have the energy required for their next strength training session while supporting muscle growth.
Helping clients maximize recovery day nutrition involves offering advice about the three macronutrients: protein, carbs, and fat.
Protein supports muscle protein synthesis. This is when the body produces protein to help repair muscles damaged by an intense workout. Protein in the diet aids in muscle repair by supplying amino acids that help heal recovering muscle tissue.
Because protein is so important to muscle growth, clients should consume the same amount as on training days. For muscle growth, this equates to one gram of protein for every pound of bodyweight, or 2.2 grams per kg.
For athletic clients wanting to build muscle and lose fat, research reveals that a slightly higher intake—2.3 grams per kg of bodyweight—is more beneficial. (2)
Foods that supply a higher level of protein include fish, poultry, nuts, and seeds. Beans, dairy products, tofu, and soy are high in protein as well.
Carbs are also important to muscle recovery. They help replace glycogen stores, supplying the muscles with more energy. Studies have also found that carbs are necessary for maximum protein absorption. (3)
The number of carbs clients should consume on a rest day depends on how active they are. If they are fairly sedentary, 3-5 grams per kg of bodyweight may be enough. Carbs should also be lowered if the client wants fat loss in addition to building muscle.
For a more active rest day, 8-10 grams per kg may be necessary to supply the body enough energy. Active rest involves performing light-intensity exercises such as walking or cycling at slower paces.
Complex carbs supply the most nutrition and include foods such as whole grains, beans, and vegetables. Incorporating these items in a client's rest-day diet helps support the recovery process.
A client's approach to fat on rest days can go one of two ways. Some will want to lower their fat intake because they know they'll be less active. This is especially true if they're concerned about their weight. Others may look at a rest day as a cheat day and be tempted to overdo it.
Either way, it's important to remind clients that there's a difference between healthy fats and unhealthy fats. Healthy fats include those found in avocados, nuts, and olive oil. Unhealthy fats are those found in processed foods such as cakes, cookies, and chips.
Healthy fats are part of a balanced diet. Typically, fat should account for 20 to 35 percent of the client's total calorie intake. Though, this amount could change depending on their specific eating program.
Because protein is so important to muscle recovery, clients may be inclined to consume protein shakes on rest days to ensure they get enough. The question is whether this is really necessary for promoting muscle recovery.
The problem with this approach is that these shakes can be high in calories and sugar. If this is not accounted for, it's easy to exceed dietary limits.
If clients are having trouble reaching their recommended protein intake, a protein shake can help. This helps ensure that muscle protein levels are where they need to be. Protein shakes are also helpful for clients with rigorous workout and weight training schedules.
For those only exercising a couple days a week, protein is best sourced from their regular diet.
There are few other things clients can do on their rest days to help support muscle recovery. Here are some recommendations you can make as their personal trainer:
Get enough rest. When you sleep, your body replenishes its muscle glycogen stores. Thus, sleep is necessary for muscle growth.
Know your limit. Optimal rest days for muscle growth vary between people and training levels. Most people workout four to five days a week and rest two to three days, but that doesn't work for everyone. If you're putting in more intense weight training days than normal, consider taking a longer rest period.
Focus on hydration. Water helps keep the joints lubricated. Some studies have found that it also reduces muscle soreness. (4)
Relieve tight muscles. If the client notices muscle tightness on rest days, foam rolling can help. Relieving tight muscles also increases flexibility, which can help once they return to the gym for their next training day.
Let go of the guilt. Sometimes rest day comes with a little guilt. The client feels bad because they didn't exercise. Reinforce that recovery time is part of a healthy workout program. In fact, if they have an intense exercise plan, they may benefit from a full recovery week.
If you want to learn more about how diet impacts fitness, the ISSA offers a Nutritionist Certification. In this course, you will learn how the body uses food and which food sources support a healthy lifestyle. It also teaches you how to create a diet that assists with losing fat and gaining muscle.
By becoming an ISSA Nutritionist, you'll learn the foundations of how food fuels the body, plus step by step methods for implementing a healthy eating plan into clients' lifestyles.
Kim, J., & Lee, J. (2014). A review of nutritional intervention on delayed onset muscle soreness. Part I. Journal of exercise rehabilitation, 10(6), 349–356. https://doi.org/10.12965/jer.140179
Mettler, S., Mitchell, N., & Tipton, K. D. (2010). Increased protein intake reduces lean body mass loss during weight loss in athletes. Medicine and science in sports and exercise, 42(2), 326–337. https://doi.org/10.1249/MSS.0b013e3181b2ef8e
P. H. Bisschop, M. G. M. de Sain-van der Velden, F. Stellaard, F. Kuipers, A. J. Meijer, H. P. Sauerwein, J. A. Romijn, Dietary Carbohydrate Deprivation Increases 24-Hour Nitrogen Excretion without Affecting Postabsorptive Hepatic or Whole Body Protein Metabolism in Healthy Men, The Journal of Clinical Endocrinology & Metabolism, Volume 88, Issue 8, 1 August 2003, Pages 3801–3805, https://doi.org/10.1210/jc.2002-021087
Cleary, M. A., Sitler, M. R., & Kendrick, Z. V. (2006). Dehydration and symptoms of delayed-onset muscle soreness in normothermic men. Journal of athletic training, 41(1), 36–45.