Nutrition Diets

Calculation of energy needs for sports activities

Calculation of energy needs for sports activities

by in Nutrition - Diets

last updated: November 06, 2015

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Athletes have different food requirements than those leading a sedentary lifestyle, especially in terms of quantity. In calculating daily energy requirements, in addition to the diet is essential to consider the caloric expenditure involved in sporting activities.

Energy needs of sports practitioners

Sportspeople have different food requirements to those with a sedentary lifestyle, especially in terms of quantity, and the daily energy calculation must also consider the additional caloric expenditure caused by sports. During the course of a day (24 hours), a sportsperson's energy needs is calculated by taking the following into account (calories consumed):


bathing, dressing, walking, driving, reading, watching television, resting in the afternoon and at night, etc.


extent and duration of physical effort


also called the "specific dynamic action of food", this is the energy consumption resulting from the digestion and assimilation of food. On average, it requires about 10% of the calories ingested. In particular, proteins require 10-35% of the total, while the carbohydrates need 5-10% and fats 2-5%


this is the energy expenditure arising from the performance of the body's vital processes: respiration, activity of the cardiovascular system, digestion, excretion, maintaining body temperature at around 37°, growth and repair of tissue cells, etc.

The basal metabolic rate varies according to age, sex, race, climate, type of activity and so on.
The cold enhances the basic calorie consumption as the body makes an extra effort to maintain a constant body temperature.

States of anxiety can increase it by up to 50%. After the age of 30, there a steady decline that reaches over 30% after age 70.

This fact constitutes one of the causes of weight gain for those who maintain certain eating habits while advancing in years. During sleep it is lowered by about 7%. You can make a simple and approximate calculation of basal metabolism in 24 hours by considering, when resting, the body consumes about 1 calorie per Kg. of body weight (0.9 for women) per hour.

Decreasing body weight

The difficulties faced by a sportsperson trying to lose body weight is essentially linked to the parallel loss of physical fitness, especially in disciplines with a muscular element. In fact, in addition to fat, they also lose minerals and muscle protein. In theory, to lose 100 grams of subcutaneous fat (which consists of 90% fat and 10% water) it is necessary to consume about 800-900 calories.
In a low-calorie diet for weight loss, liquids are mainly lost in the first few days (a lower carbohydrate intake leads to the elimination of water as there is a cell ratio of 2.8: 1 between carbohydrates and body water). Subsequently to this, the subcutaneous fat is damaged, but a defensive mechanism called "saving" also comes into play, which involves a much lower calorie consumption (up to 20%) to support the basal metabolism. In addition, a lower calorie consumption equal to the work carried out is needed, with and assimilation of the food ingested.

Optimal weight loss, which keeps optimal organ and muscle efficiency almost in tact, should not go beyond a subcutaneous fat consumption exceeding 2 kg every 15 days.

More specifically, 1% of the actual weight per week. In a diet with a balance between the calories consumed and calories expended, to lose 1 kg. of fat per week you should reduce your daily intake by about 1150 calories. Furthermore, the food principles must always be present and balanced, in that:

  • fats convey lipid-soluble vitamins
  • glycides stop the state of ketosis resulting from the consumption of subcutaneous fat
  • proteins are essential because of their plastic action.

Minimisation of body weight


If we experience symptoms such as nervousness, insomnia, physical and mental exhaustion, it means that our weight loss diet is not being applied properly.

One of the simplest methods used to decrease body weight is endurance running or similar activities (cross-country skiing, cycling, swimming, etc.).

One very simple calculation to determine caloric expenditure when running is to consider that a trained athlete expends about 0.9 Calories per Kg of body weight for each Km covered, regardless of the rhythm they follow. In fact, it is not speed that leads to a greater calorie consumption but rather the total work.

Therefore, in order to impact the loss of subcutaneous fat, it is preferable to carry out an undemanding but activity prolonged rather than an intense and brief one.
For example, it is possible to have a general idea of ?calorie consumption with regard to running (E. Arcellis):

Calories consumed during walking and running

1 Cal x body weight (in Kg) x Distance covered (in Km)
70 Kg woman who runs 5 Km.: 70 x 5 = 350 Calories

The consumption of body fat can be deduced from (formula by E. Arcellis):


Fat consumed (in grams) when walking or running
Distance covered (in Km) x body weight (in Kg): 20
5 Km x 70 kg =
350350: 20 = 17.5 g.

A good weight loss programme must take into account the calories ingested and consumed in 24 hours. Obviously the quality of the food ingested should also be a factor.
Therefore we must consider:

  • number of calories ingested
  • number of calories consumed through:
    • commonly performed activities
    • sports activity carried out
    • diet-induced thermogenesis, i.e. removing about 10% of the total calories ingested, which is used by the enhanced cellular metabolism of the digestive process
    • basal metabolic rate over 24 hours, calculated using the formula shown above, given that sleep lowers it by about 7% (it is already included in the tables concerning normal and sporting activities).

Alternatively, you can simply weigh the athlete on a daily basis and check the weight oscillations over the course of two weeks and take steps accordingly.

It should also be kept in mind that weight loss diets involve a considerable consumption of subcutaneous fat.

This circulates ketone bodies (acid derived from acid acetoacetic acid), which increase the acidity of the blood (which is added to that generated from training).

One serious mistake often made by athletes is to overlook the presence of carbohydrates in the diet. Carbohydrates are the primary suppliers of energy and, in the case of weight loss, lessen the blood's tendency towards acidity by blocking the action of the ketone bodies.
Energy expenditure for some common tasks (Cal. per kg. of body weight per hour of activity)


Type of activity Calories (per kg of b.w./h)
Sleep 0.93
Personal needs (washing, etc.) 3.00Sitting
1.43Standing 1.50Walking at

4 km/h 2.86Walking
at 6 km/h 4.28Driving
a car 1.90Cycling
at 15 km/h 5.46Cycling
at 22 km/h 9.25

Energy expenditure of certain recreational and sporting activities (referring to an actual minute of physical activity without breaks)


Type of activity Cal/min

dancing 4.3Dynamic dancing 11.3Baseball 4.6Recreational boating

Competitive boating
Horse riding

at walking pace
3.3Horse riding at trot

8.5Recreational cycling 5.9Competitive cycling 26.0
running 10.4Marathon running 20.0

5.9Golf 5.2Recreational swimming 9.1Competitive swimming 25.0Basketball14.3 Handball 13.7Volleyball 8.5 Recreational
skating 5.2Speed skating 28.6Fishing 3.9Recreational downhill skiing
12.0Competitive downhill
21.5Recreational cross country skiing

12.0Competitive cross country skiing21.5Fencing 9.8Weightlifting 127.0Singles tennis

11.1Doubles tennis 9.1Table tennis 5.2Archery 4.6

Some devices normally used for weight loss are not only ineffective but can be harmful to health:


only cause a momentary lose water and minerals salts such as sodium, potassium and chlorine.

This can lead to cell dysfunction, nervousness, muscle cramps and loss of physical efficiency. Diuretics are included in the banned substances on the DOPING list.


can only help recovery from muscle fatigue and do not in any way affect the subcutaneous fat reserves (the only person who can consume calories and lose weight is the masseur!).


do not allow sweat to evaporate and therefore only give the impression of increased sweating.

If they come into contact with skin, they can cause irritation and alter the perspiration between the skin and the environment (body heat regulation).

Body mass index

Increased body weight

In disciplines divided into weight categories in particular, some sportspeople may need to gain weight, especially muscle mass.

Weight gain understood as "active" weight can be obtained by appropriate nutrition combined with training strategies that promote protein synthesis.

It can be helpful to work with overloads measured according to the principles of bodybuilding.

The diet should be based on the ingestion of carbohydrates with high energy content that are easy to digest (rice and pasta, potatoes, biscuits, jams, fruit compotes, etc.), proteins (milk and easily digestible meat like veal and chicken) and limited fats (preferably olive oil).

Consumption of vitamin E, B12 and protein rich in branched chain amino acids (see "Nutritional Supplements") can promote protein synthesis. Appetite may be increased by taking a tablespoon of glucose diluted in juice half an hour before meals. A high-protein diet should take into account the right intake of carbohydrates, water, vitamin B1 and potassium needed to facilitate the disposal of nitrogenous waste.

Ideal body weight formula

There are different ways of calculating ideal body weight, and these are the main ones:


Men: (H cm - 100) - (h cm - 150) / 4 = Kg

Women: (h cm - 100) - (h cm - 150)/2 = Kg


Men: (h cm - 100) = Kg

Women:(h cm - 104) = Kg

Van Der Vael

50 + (h cm - 150) x 0.75 = Kg


0.8 x (h cm - 100) + age/2 = kg


(h cm - 100) + age/10 x 0.9 = Kg


Once ideal body weight has been calculated, we can calculate the relative weight, i.e. the ratio between the current weight and the ideal weight, multiplied by 100:

Relative weight

Relative weight = (Weight/Weight Ideal) x 100


Obesity > 120

Overweight 110-120

Normal weight 90-110

Mild thinness 80-90

Moderate thinness 70-80

Severe malnutrition <70

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