Calories in vs Calories out (Energy intake & expenditure)

Energy expenditure also known as “calories out” is a combination of the energy that is being used (calories that are burned):

• during the rest,
• the energy that is required for other bodily functions such as digestion as well as
• the energy that is required for participating in physical activities.

The energy is measured in calories which are units of energy (1 calorie is 2 units of energy.)

There is small calorie also known as gram calorie. It is estimate of energy that is required to raise temperature in 1 gram of water by 1 degree (Celsius) in specific conditions (1 atmosphere).

The large calorie consists of 1000 small calories and is used as dietary calorie (also known as kilogram calorie (kcal). Respectively, this is the amount of energy that is required to raise kilogram of water in the same conditions. The carbohydrates, fats and proteins hold different energetic value. Carbohydrates and proteins are 4 kcal per every gram while fats are more than double at 9kcal per every gram.

WHAT AFFECTS ENERGY EXPENDITURE?

Firstly, the energy amount requirement at rest is also known as basal metabolic rate (BMR) which is the amount of calories (energy unit) that are burned without any physical activity.The calories are burned at rest state because the energy is required for blood circulation, respiration (breathing) and maintaining body temperature and building up (anabolism), breaking down (catabolism) cells in the body.

The amount of calories that are required for basal metabolic functions will depend on different variables such as gender, height and weight (lean body mass: amount of fat).

Secondly, the energy expenditure is also affected by the TEF (thermogenic effect of food). The thermic effect of food is the amount of energy that are required just to digest the food so it can then be utilised for energy (on average 10% off all food eaten is burned during digestive processes). Depending on what type of macronutrient is consumed the TEF will vary. Fats (2-3%) and carbohydrates 6 to 8% having lower percentage that is being burned during digestion that protein from which 25% or ¼ is burned up during digestion. Therefore diet higher in protein may aid fat loss as while eating the same amount of calories athlete may be able to decrease his weight more efficiently. The calories are burned during urination, flatulence and defecating.

Finally, the calorie expenditure (energy expenditure) will be influenced by physical activities. This will apply to every athlete as they will expend much higher amount of calories during high intensity exercise. Number of training hours a day and number of training days a week in addition to intensity level will affect the total number of calories that are expended. Calorie expenditure can be estimated by using different formulas.

There are two processes that occur in human body which are anabolism and catabolism. Catabolism is the breakdown cells which systematically occurs together with anabolism which is the building of the cells. Athletes will want to stay in anabolic state most of the time which will help them to increase performance and increase muscle mass.

CALORIE INTAKE – FOOD

The energy expenditure will be balanced with energy intake also known as “calories in”. Athletes will have to eat more food than regular person to compensate their high energy expenditure. This is crucial to sports performance as it helps to maintain high amount of energy, focus as well as reduce injury.

After determining basal metabolic rate athletes will have to determine their calorie maintenance level which is when calories in=calories out or energy intake=energy expenditure. This is when athlete will be maintaining his/her current weight. When athlete will have to increase their weight or increase their performance by increasing fitness components such as strength the calorie intake or energy intake will have to be higher than calorie out or energy expenditure.  By doing this the athlete will achieve calorie surplus (positive energy balance). Calorie surplus can have a negative effect on people that are living sedentary lifestyle as it will result in weight gain which will be due to increase in the amount of adipose tissue instead of muscle.

The main preferred source of energy is carbohydrates. They fuel all processes in the body including the brain function which uses approximately 20% of daily energy (500kcal if male eats 2500kcal a day). All carbohydrates are converted into glucose but the time varies depending on the type of the carbohydrate (Simple/Complex) and other factors such as amount of fibre/fats in the meal. The secondary source of energy is fats, it can be referred to as a primary energy source during long duration activities. The proteins are used for building the cells in the body (muscles, nails, hair and blood). The required amount for athlete is much higher than someone who is sedentary and to who the government guidelines will apply. For athlete the requirement is higher as there is increased muscle breakdown (catabolism) therefore more protein is needed to rebuild (anabolism). The leaner person is the harder it is to maintain muscle mass, therefore when cutting/losing weight the amount of protein requirement will increase gradually. This also happens because there also is less amount of total energy (calorie deficit). If eating at or above maintenance it will be 0.8 to 1.2 grams per kilogram of body weight per day whereas if eating below the maintenance it doubles to around 1.6 to 2.7 grams per kilogram of body weight per day. The protein intake will depend on various other factors. Athlete will have higher requirement as he/she will train for specific goals with progression which will require both calorie surplus and higher protein intake when compared to someone who is doing light exercise without specific training goals. In some cases doctors might recommend a low protein diet for medical reasons person is having. In most cases when there are no medical restrictions, athlete wants to gain muscle mass or maintain it and has low body fat percentage the protein requirement will be in range from 1.6g to 2.7g per every kilogram of body weight. The protein is not classified as an energy source but it can be converted into glucose during a process of gluconeogenesis.

For athletes it is recommended to eat in slight calorie surplus usually 300-500kcal surplus as in this way they will be able to avoid adding unnecessary weight in form of adipose tissue.

In conclusion:

• To gain weight – eat in caloric surplus
• To lose weight – eat in caloric deficit
• To maintain weight – eat at caloric maintenance

Read here how to calculate your calorie intake