Hitting the gym is only half the battle, and that’s if we’re speaking figuratively. Realistically, your workout is actually less than one-third the battle! No, that isn’t a typo.

In actuality, the two most important aspects of your lifestyle on this journey to build and maintain lean muscle are: nutrition and rest. That’s right, it’s that simple. In this article, I’m going to provide you with a comprehensive guide about how to eat to build lean muscle (Hint: It’s not complicated at all).


I’m sure you’ve heard that word somewhere in some lifetime before. “Macro” is short for macronutrient. A macronutrient is one of three nutrients that your body needs, in large quantities, to operate optimally. This is especially important when we account for not only maintaining optimal health, but achieving and maintaining exceptional health and fitness levels. Your macronutrients include:

  • Carbohydrates
  • Fats
  • Proteins

These three nutrients are the building blocks of your diet. Each has its own unique function, but they all work in conjunction together. Let’s break it down, shall we?

Carbohydrates – The Energetic One


Carbohydrates (carbs) are responsible for fueling your body during exercise and fueling your nervous system. In short, your carbs are your energy (one source, at least)!

Another important function of carbs is to preserve protein for the reparation of muscle tissue. At a carb-deficit, it’s much more difficult to make muscle gains simply because your body begins to break down protein, which should be used for your muscles, for energy.

An oft overlooked but critical function of carbs is insulin regulation.

Most people only associate the importance of insulin to the lives of diabetics, but understanding insulin’s function is extremely beneficial when looking to eat to build lean muscle.

Insulin is an anabolic hormone. Does that sound familiar? If not, how about testosterone or growth hormone? That’s right: Insulin is in the same family of those hormones that facilitate muscle growth, bone mass, and strength gains, not to mention helping with reproductive organ function, skin, and mood and health overall! Within the bloodstream, insulin transports carbs, amino acids, and fats to your cells.

Now that we know insulin is another great hormone for building lean muscle, we understand why it’s important for our bodies to be receptive to it.

Carb intake is the primary driver of insulin sensitivity because carbs spike the release of insulin through the body. Like everything else in life, too much of anything is usually a bad thing. With too many carbs in our diets, there would be a constant flow of insulin through our bloodstream.

Therefore, it is important to track your carb intake and plan ahead to switch it up consistently so our bodies don’t become used to the insulin and we remain as receptive as possible to it.

Common sources of carbs include grains like rice, bread, and pasta, starches like potatoes, and fruits.

Fats – The Misunderstood One


Oh, fats. Such negative connotations bombard the mind just at the mentioning, but fats are just as an important macronutrient as its other siblings, carbs and protein.

Fats are the other energy source our body uses to function, but they are more so stored as an energy reserve. This means fats are the preferred energy source for lower-intensity, higher-duration activity such as aerobics which include brisk walking, jogging, or biking.

Other functions of fats are insulation for body temperature regulation, protecting organs, and transporting fat-soluble vitamins through the bloodstream.

Because our bodies use both carbs and fats for energy, we need to understand how to balance and schedule these two macros in our diets, seamlessly.

Carbs are used for quick, anaerobic activities such as lifting and sprinting. Fats are used for enduring, aerobic activities such as jogging and bike-riding. If we consume too much of one or the other or if we fail to plan our consumption of fats and carbs according to our activity that day, we won’t be able to maximize the benefits of either.

Common sources of fats include avocados, cheese, nut butters, and whole milk.

For a more detailed explanation of fats, check out this article!

Proteins – The Cool One

And here we are at the main squeeze that everyone talks about when it comes to a muscle-building diet: Protein.


When thinking of how to eat to build lean muscle, protein is the first thought that comes to mind because it is directly related to actually building muscle. Proteins are one of the foundations of the body tissue of organs, hair, skin, nails, bones, tendons, and ligaments, and muscles.

Proteins are not only essential as building blocks for body tissue. They also help with the regulation of the body’s metabolism and pH balance.

As mentioned earlier, proteins are ideally preserved for the reparation of muscle tissue while carbs are the ideal source of energy for short, intense spurts of anaerobic activity. However, if the body hasn’t been sufficiently loaded with carbs for the period of activity presented, proteins would be substituted for carbs as they provide just as much energy density per unit.

Common sources of protein include red and white meats, nuts, lentils, eggs, and fish.

The Big 4

Now that we’ve got an understanding of each of the three macros, it’s time to put some actual numbers to each of them, along with calories, and create a foundation for planning ahead to diet to build lean muscle. These numbers will vary from person-to-person, but we can at least get a general idea.

Before we proceed, I highly recommend the app MyFitnessPal for all your calorie and macronutrient tracking needs!

Calorie Goal – To Gain or to Lose?

Calorie goals are the easiest to set simply because the math is basic subtraction, and it all depends on what you’re aiming for. You either want to gain weight or lose weight, but in both cases you want to build lean muscle.

Calorie Intake > Calorie Expense => Gain Weight

Calorie Intake < Calorie Expense => Lose Weight

Setting a calorie benchmark will allow you to more accurately gauge the amount of calories you’d want to consume to achieve your goal. For our benchmarks we’ll use Person A, a 30-year old male who weighs 180 lb. To calculate Person A’s maintenance caloric intake, we will use a factor of 15.5, assuming they’re moderately active, and multiply that by their body weight in pounds:

180 lb. x 15.5 = 2,790 calories to maintain weight

Now whether Person A wants to lose weight or gain weight is entirely up to them, but let’s take both scenarios.

To gain weight at a healthy rate, we’d take that maintenance caloric intake and multiply it by a factor of 1.1 – 1.2. Because Person A is moderately active, let’s take a factor of 1.12:

2,790 calories x 1.12 = ~ 3,125 calories to gain weight

So to gain weight at a healthy rate, we could approximate that Person A would need 3,125 calories per day. Keep in mind that this is just a benchmark to begin with. Also, depending on whether the day is a rest day or a training day, you’d want to alter your benchmark based on the amount of macros you’re aiming for. We’ll talk more about that here in a bit…

To lose weight at a healthy rate, we’d take the same maintenance caloric intake but multiply it by a factor of 0.7 – 0.8 (or a factor of 0.6 for rapid weight loss, but I wouldn’t recommend it). Let’s take a factor of 0.75 for Person A:

2,790 calories x 0.75 = ~ 2,093 calories to lose weight

ACTION ITEM: Go ahead and calculate your maintenance caloric intake. Establish whether you want to gain or lose weight and use the multiplication factors above to get a general idea of a benchmark!

Protein Goal – More ≠ Better

Most of us have the misconception that an over-indulgence of protein is a good thing concerning building muscle. Though it is true that protein is directly related to the body repairing (thus building) muscle, more is not always better. In fact, research shows that about 0.73 g of protein per 1 lb. of body weight is recommended for healthy adults with intense levels of physical activity.

A factor of about 0.9 g of protein per 1 lb. of body weight is safe for healthy adults, but a consistent protein intake this high can be counterproductive long-term, causing a host of issues with the digestive system and kidneys. Let’s use a factor of 0.8 for Person A:

180 lb. x 0.8 = 144 g of protein per day = 576 calories from protein (4 calories per 1 g of protein)

Unlike fat and carbs, protein consumption should be consistent from day-to-day, only changing as your weight changes.

Carb and Fat Goals – The Dynamic Duo

Remember when I said this:

“…it is important to track your carb intake and plan ahead to switch it up consistently so our bodies don’t become used to the insulin and we remain as receptive as possible to it.”

This section is where we put those words into action!

Since carbs are the body’s preferred source of energy for those high-intensity, anaerobic activities, we’ll use a higher factor for training days than for rest days. For training days, it’s effective to use a factor of 2 – 2.5 g of carbs per 1 lb. of body weight. The number depends on your current body fat percentage. The higher your body fat percentage, the lower your carb intake should be. Let’s say Person A is at 12% body fat, which is pretty good:

180 lb. x 2.2 = 396 g of carbs per training day = 1,584 calories from carbs (4 calories per 1 g of carbs)

To find the ideal fat intake, we take the goal calorie benchmark (whether we want to gain or lose weight) and subtract the sum of the number of calories from protein and the number of calories from carbs. The difference is the number of calories we want from fat:

Calories from Fat = Goal Calorie Benchmark – (Calories from Protein + Calories from Carbs)

Let’s assume Person A wants to gain weight:

Calories from Fat = 3,125 – (576 + 1,584) = 965 calories from fat

965 calories from fat = ~ 108 g of fat per training day (9 calories per 1 g of fat)

Note: Heard of those zero-carb diets that work so well for weight loss? This is because the body is forced to use protein and fat as its energy sources due to lack of carbs. This is not ideal for building lean muscle, but can be effective if your primary goal is to lose weight.

On that note, let’s calculate what would be needed on rest days still assuming Person A wants to gain weight. The difference will be lower carb intake since the body’s preferred energy store for aerobic activities, like walking and jogging, is fats. This time, we’ll use a factor of 1 g of carbs per 1 lb. of body weight:

180 lb. x 1.0 = 180 g of carbs per rest day = 720 calories from carbs (4 calories per 1 g of carbs)

We use the exact same method to find the ideal fat intake on rest days, except we use the maintenance calorie intake on rest days instead of the goal calorie benchmark:

Calories from Fat = 2,790 – (576 + 720) = 1,494 calories from fat

1,494 calories from fat = ~ 166 g of fat per rest day (9 calories per 1 g of fat)

Putting it All Together

Now that we’ve made our calculations for Person A, let’s put their macronutrition goals together:

Training Days

Calories: 3,125

Protein: 144 g

Carbs: 396 g

Fat: 108 g

Rest Days

Calories: 2,790

Protein: 144 g

Carbs: 180 g

Fat: 166 g

Remember that by keeping the carb intake fluctuating between training days and rest days, the body never stagnates with the insulin receptiveness and is more primed to make the best use of the hormone.

ACTION ITEM: Perform your calculations for your goal protein, carb, and fat intakes based on your fitness goal. Feel free to ask for help if necessary!

The Most Important Ingredient of All


DRINK WATER. That is all.

Seriously. Please do not neglect the compound that allows all of our bodily functions to operate optimally and is found in nearly every food. Do not neglect water consumption.

The common standard for water consumption is 64 oz. (8 cups) per day. In reality, the amount of water we need is not universal; we’re all different.

A safe benchmark to set for water consumption can be calculated with your body weight and level of physical activity. It is recommended to multiply your body weight by a factor of 0.67, then add 8 – 12 oz. per every 30 minutes of physical activity.

Let’s take Person A again and assume they’re active for an average of 45 minutes per day every week:

(180 lb. x 0.67) + (8 oz. x 1.5) = ~133 oz. or ~16.5 cups of water per day

Don’t worry, you won’t become a fish! Remember that plain water isn’t the only source. If you’re eating correctly (and you will be), you’ll also be hydrating with food and other drinks.

It’s very easy to forget to hydrate throughout the day, which is why I highly recommend in investing in a 64 oz. reusable water bottle to keep track of your water consumption. I fill mine up every morning and got into the habit of taking large, random swigs throughout the day while working. Naturally, you’ll be consuming more on training days, especially during your workout, but aim for at least your calculated amount.

Now You Know!

Now you have a solid foundation and know exactly how to eat to build lean muscle. From this point forward, it is up to you to put your education, or theory, into practice.

The key to fitness nutrition is consistency. I don’t expect you to be perfect, none of us are. There may be days when you don’t log every meal, or there may be days when you decide to cheat and go over your fat or carb intake goal. The point isn’t to be perfect.

The point is to be consistent.

If you slip up, own it and hop right back on it. The most important thing is to establish a nutrition plan (based on what you read above) and create a log that will enable you to track your progress. Let’s get to it!

ACTION ITEM: Implement a log to track the food and drink you consume starting tomorrow. Apps like MyFitnessPal make this an extremely simple and streamlined process!