Science of Macronutrients Intake for Fat Loss, Muscle Gain & Strength
This is the third of the series of six articles, it is intended to help people arrive at informed decisions based on science about their nutrition requirements and program for fat loss, muscle gain and building strength so that they can avoid making mistakes. It is not intended as a substitute for medical advice or medical treatment.
Macronutrients are the nutritive components of food that the body needs for energy and to maintain the body’s structure and systems. There are three principal classes of macronutrients: protein, carbohydrate and fat. Calories intake determines whether weight is gained or lost, however, macronutrients (carbohydrate, protein, and fat) determine whether that change is fat or muscle mass. What this means is that taking macronutrients in the right proportions helps us reach fitness goals faster and better.
Each macronutrient has a specific role in human body that allows the body to function properly: (Source: https://en.wikipedia.org/wiki/List_of_macronutrients)
- Protein: Protein is an important building block of bones, muscles, cartilage and skin. In fact, hair and nails are comprised mostly of protein. It helps with muscle repair, muscle maintenance and muscle growth. Food Energy – 4 Calorie/gm.
- Carbohydrate: Body needs carbohydrate for energy. Carbohydrates are broken down to glucose which is used for energy by body’s cells. The biggest consumers of glucose are brain and muscles. This helps in sparing the use of proteins for energy. Food Energy – 4 Calorie/gm.
- Fat: Storing energy is one of the main functions of fat. The body uses fat as energy source, it is the major storage form of energy in the body. Fat also has many other important functions in the body. Fats in food come in several forms, including saturated, monounsaturated, and polyunsaturated. Food Energy – 9 Calorie/gm.
Every cell in the human body contains protein. One needs protein in diet to help body repair cells and make new ones. It is an important building block of bones, muscles, cartilage and skin. Protein is also a critical part of the processes that fuel energy and carry oxygen throughout body in blood.
Why is protein important?
Protein provides the building blocks for muscle mass. Protein helps us to recover and grow from our training, helps preserve muscle when dieting.
Protein is very important during a cutting (losing weight) program. Evidence suggests that eating protein can increase the number of calories one burns by boosting metabolic rate (calories out) and reducing appetite (calories in).
The other two important facts to remember are:
- Muscles are largely made of protein
- Muscles are dynamic and constantly being broken down and rebuilt.
Hence, to gain muscle, body must synthesize more muscle protein than it breaks down. Therefore, there needs to be a net positive protein balance in the body and one who wants to build muscle often needs to eat more protein, as well as exercise. A higher protein intake can help build muscle and strength.
How much protein should one consume?
There’s a difference between avoiding a nutrient deficiency and eating the optimal amount of a nutrient.
The Recommended Dietary Allowance (RDA) is the amount of a nutrient one needs to meet basic nutritional requirements. The RDA for protein is a modest 0.8 grams of protein per kilogram of body weight. However, this recommendation is based on structural requirements but disregards use of protein for energy metabolism. This amount varies for cutting and bulking programs.
Protein intake should be enough to cover the muscle growth and preservation benefits. However, it should be kept within a limit so that we do not have to reduce the number of carbohydrates we can eat while keeping to our calorie intake plan. One must not forget that the most important macronutrient for performance is carbohydrate, reducing carbohydrate intake affects our performance.
As compared to bulking, protein needs are slightly higher during cutting because glycogen and fat stores in body decrease and the body is forced to rely more on protein as an energy source. Body can break down both dietary protein and muscle protein to do this, so setting protein intake higher can help limit this.
Also, during cutting, eating more protein may help suppress hunger and appetite for hours after eating and thus may help in keeping calorie intake down. Protein increases production of hormones like PYY and GLP-1, both of which help one feel full and satisfied. In addition, it helps reduce levels of ghrelin, also known as the “hunger hormone”.
It helps to know that the satiating property of dietary protein is influenced by when the protein is consumed. Studies have shown that protein intake at breakfast has a greater effect on satiety than during later meal times. There are several explanations as to why this is the case. Firstly, protein has a greater thermogenic effect than carbohydrates and fat, which enables the body to burn more calories. Secondly, a high protein breakfast appears to slow gastric emptying, which attributes to the fact that protein appears to be the most satiating macronutrient. Finally, a high protein breakfast increases the activity of glucagon, which activates the pathways for glucose synthesis. One study showed that fat loss was approximately twice as much in the high-protein diet group than the moderate-protein diet group in overweight and obese individuals. (Source: https://en.wikipedia.org/wiki/Weight_management)
Taking all studies into account our guideline:
- 2–2.6 grams of protein per kg of bodyweight is sufficient for conserving muscle mass on a cutting diet.
- The recommended protein intake for most healthy individuals doing a bulk is 1.6-2.2 g/kg of bodyweight.
As 2.2 gram per kg of bodyweight is the common number between the above two recommendations for cutting and bulking, this is a good target to set for protein intake regardless of whether cutting or bulking.
Therefore, whether you want to maximize the amount of muscle you can build and minimize the amount of fat you’ll gain or whether you’re eating in a calorie deficit and you want to maximize muscle retention and fat loss, 2.2 gram per kg of bodyweight is a good target.
Protein Powder or Real Food?
Protein powders have a higher concentration of protein and are useful in conveniently meeting protein targets. However, meat, fish, dairy products and whole grains offer other nutrients such as vitamins, minerals, carbohydrates and healthy fats along with proteins naturally found in them.
In general, it’s the quantity of protein rather than the source of protein that has major effects on metabolism, whether it’s for weight loss, appetite control, or recovery from exercise.
The question is: How well is your diet meeting your protein needs?
Now, let’s say you’re not getting or finding it hard to get enough protein from food. This is where protein powder really comes in handy. If you’re not getting enough protein from food, a protein supplement is beneficial. Protein powders are a great way to add more protein into the diet if you can’t meet those needs through just food.
Basically, protein powder is the lowest-effort, highest-efficiency way to be sure you’re getting enough protein with a single scoop. However, it is absolutely possible to consume adequate protein from real food such as meat, fish, poultry, eggs, dairy, beans, lentils, soy products, nuts, seeds and whole grains as they all provide dietary protein.
Carbohydrates are central to nutrition and are found in a wide variety of natural and processed foods.
In food science the term “carbohydrate” often means any food that is particularly rich in the complex carbohydrate starch (such as cereals, bread and pasta) or simple carbohydrates, such as sugar (found in candy, jams, and desserts). Often in lists of nutritional information, such as the USDA National Nutrient Database, the term “carbohydrate” (or “carbohydrate by difference”) is used for everything other than water, protein, fat, ash, and ethanol. It also includes dietary fiber which is a carbohydrate but which does not contribute much in the way of food energy (kilocalories), even though it is often included in the calculation of total food energy just as though it were a sugar. (Source: https://en.wikipedia.org/wiki/Carbohydrate)
Why is carbohydrate important?
Carbohydrates are the body’s main source of energy. In their absence, body uses protein and fat for energy. Carbohydrates have impact on performance and hormonal function. They replace muscle glycogen, which is used by muscles during workouts. Carbohydrates are fast-acting energy source (containing 4kcal per gram) and turn into energy as soon as they are ingested.
Low-carbohydrate diets may miss the health advantages – such as increased intake of dietary fiber – afforded by high-quality carbohydrates found in legumes and pulses, whole grains, fruits, and vegetables.
How many carbs should one consume?
During cutting phase, aim for a carb intake that’s 40% of your daily calories to maximize fat loss. Still, consume no less than 3-4 grams of carbs per kg of bodyweight each day. (Source: https://www.healthline.com/nutrition/how-many-carbs-per-day-to-lose-weight)
During the bulking phase, eat about 4-7 g/kg of body weight of carbohydrates per day.
Fats are the main components of common food products like milk, butter, tallow, lard, bacon, and cooking oils. They are a major and dense source of food energy and play important structural and metabolic functions including energy storage. The human body can produce the fat that it needs from other food ingredients, except for a few essential fatty acids that must be included in the diet. There are four major dietary fats in the foods we eat: Saturated fats, Trans fats, Monounsaturated fats and Polyunsaturated fats.
Why is fat important?
Dietary fats are essential to give body energy and to support cell growth. They also help protect organs and help keep body warm. Fats help body absorb some nutrients and produce important hormones, too. Dietary fat is necessary for regular hormonal function. One should never attempt to eliminate it from a diet.
Triglycerides, cholesterol and other essential fatty acids–the scientific term for fats the body can’t make on its own–store energy, insulate us and protect our vital organs. They act as messengers, helping proteins do their jobs.
How much fat should one consume?
The general recommendation is that 20–30% of your calories should come from fat when bulking, and 15–25% when cutting. (Source: https://pubmed.ncbi.nlm.nih.gov/15107010/) One gram of fat contains 9 calories, so anyone on a 2,000-calorie regimen should eat 33–55 grams of fat per day on a cutting diet.
The reason for the lower range when cutting is because of the relatively higher importance of keeping up carbohydrate intake for performance.
We calculate calorie intake for cutting or bulking as given in the second article of this series titled “Calorie Intake”. Let us take up “Cut for fat loss” scenario. As mentioned there this works out to 1100 calorie deficit per day for 1 kg fat per reduction per week.
TDCI = TDEE – (Body weight x target weekly weight loss rate x 1100)
John Doe is a 40 years old male, weighs 85 kg, 180 cm tall and is “Mostly Sedentary”. John Doe wishes to lose weight with a target weekly rate of 0.75 percent.
Age = 40
Height = 180 cm.
Weight = 85 kg.
Activity Level Multiplier = 1.2 (little or no exercise, desk job)
Target Weekly Weight Lose Rate = 0.75 percent = 0.0075
- BMR for Men = 66.47 + (13.75 * weight [kg]) + (5.003 * size [cm]) − (6.755 * age [years])
- TDEE = Activity Level Multiplier * BMR = 2785.35
- TDCI = TDEE + (Body weight x target monthly weight gain rate x 300)
BMR = 66.47 + (13.75 * 85) + (5.003 * 180) – (6.755 * 40) = 1865.56 = 1866
TDEE = 1.2 * 1866 = 2239.20 = 2240
For 0.75% weekly rate:
TDCI = 2240 – (85 * 0.0075 * 1100) = 2240 – 701.25 = 1538.75 = 1539 Calorie
For 0.5% weekly rate:
TDCI = 2240 – (85 * 0.005 * 1100) = 2240 – 467.5 = 1772.5 = 1773 Calorie
As mentioned above the general recommendation is that 15–25% of calories should come from fat when cutting. Since John Doe doesn’t have any particular preference for high or low fat intake, so he chooses to consume 20% of his calories from fat. This is 355 kcal, which is approximately 40 gm.
Different cases of bulking and cutting can be calculated accordingly.
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- List of macronutrients: Macronutrients that provide energy
- Weight Management https://en.wikipedia.org/wiki/Weight_management
- How to Follow a Cutting Diet for Weight Loss https://www.healthline.com/nutrition/cutting-diet
- Is bulking and cutting the ultimate way to build muscle? https://www.bbc.co.uk/food/articles/bulking_and_cutting
- Carbohydrate https://en.wikipedia.org/wiki/Carbohydrate
- How Many Carbs Should You Eat per Day to Lose Weight? https://www.healthline.com/nutrition/how-many-carbs-per-day-to-lose-weight
- Macronutrient considerations for the sport of bodybuilding https://pubmed.ncbi.nlm.nih.gov/15107010/
Abhinav Malhotra is an award-winning personal trainer, coach and sports nutritionist in Dubai, UAE. He also offers online services to clients around the world. A personal trainer par excellence, Abhi has worked with the world’s leading fitness chains, supplement brands and founded his own fitness academy in India. He has achieved successes for many clients from all backgrounds and has trained the Indian Army Rugby Team. He is the first International Kettlebell Sport athlete from India.