Exercise Nutrition

Carbohydrates Exercise Exercise Nutrition Fats Health Mental Well-being Protein

Daily Dietary Intake

The energy we have for our daily activities is derived from the foods and drinks that we consume. These consist of macronutrients (carbohydrates, protein, and fats) and micronutrients (vitamins and minerals). The focus here will be on the macronutrients.

The Institute of Medicine (1) recommends that our daily dietary intake consists of 45–65% carbohydrates, 10–35% protein, and 20–35% fat. This is to maintain health and is for the general population. Your daily intake requirements may differ depending on your level of physical activity.

Carbohydrates and protein both contain 4 kilocalories (kcals) per gram, whereas fat contains 9 kcals per gram. Each kcal equates to 4.184 kilojoules (KJ) of energy. Therefore, each gram of carbohydrate and protein is equivalent to 16.74 KJ of energy and one gram of fat equates to 37.66 KJ (2).

 

Carbohydrates

 

Individual Energy Requirements

Energy requirements are different for everyone and depend on an individuals basal metabolic rate (BMR) and their physical activity level (PAL). BMR represents the rate of energy use in order to maintain resting bodily functions such as breathing, heartbeat, keeping warm. For most individuals, this is 1.1 kcal per minute (2). BMR may be calculated using the following formula (3):

BMR for Men = (10 x weight in kg) + (6.25 x height in cm) – (5 x age) + 5

BMR for Women = (10 x weight in kg) + (6.25 x height in cm) – (5 x age) - 161

 

PAL rates range from 1.4–1.9, where 1.4 represents a very low level of physical activity such as work or leisure time; 1.6 for women and 1.7 for men represents moderate intensity levels of physical activity; and 1.8 for women and 1.9 for men represents high levels of physical activity (2). Energy expenditure is calculated using the following formula:

Energy expenditure = BMR x PAL

 

Macronutrient Recommendations for Physically Active People

Carbohydrates

Carbohydrates are the main source of energy. Carbohydrate sources include fruit and vegetables, rice, and cereals. Table 1 is a good guide and based on different level of psychical activity (4):

 a close up of a fruit

 

Table 1: Recommended Daily Carbohydrate Intake by Physical Activity Level

Activity

Recommended Carbohydrate Intake Per Day

Low

Low intensity

3-5 g/kg body weight

Moderate

Moderate intensity (e.g., 1 hour per day)

5-7 g/kg body weight

High

Endurance training, 1-3 hours per day at moderate-high intensity

6-10 g/kg body weight

Very high

4-5 hours per days at moderate to high intensity

8-12 g/kg body weight

 

 

Table 2 provides fuelling strategies for various exercise situations (4).

Table 2: Carbohydrate Fuelling Strategies.

Fuelling Strategy

Exercise Duration

Recommended Carbohydrate Intake

Examples of Carbohydrate Sources

General fuelling

Less than 90 minutes

7-12 g/kg/day

Carbohydrate-rich sources, low fiber, easily consumed for gut comfort

Carbohydrate loading

More than 90 minutes of continuous exercise

10-12 g/kg/day starting 36-48 hours before event

Small regular snacks

Fast refuelling

Less than 8 hours of recovery before next demanding event

1-1.2 g/kg for the first 4 hours, then resume daily carbohydrate needs

Carbohydrate-rich foods and drink

Pre-event fuelling

Before exercise of more than 60 minutes

1-4 g/kg, 1-4 hours before exercise

Carbohydrate-rich foods and drinks of preference and practicality

During brief exercise

Less than 45 minutes

Not required

-

During sustained high intensity exercise

45-75 minutes

Small amounts including mouth rinse

Carbohydrate drinks and snacks that are convenient to consume. Products with glucose and fructose mixtures are a good choice.

During endurance or stop and start events

1-2.5 hours

30-60 g/hour

During ultra-endurance exercise

More than 2.5 hours

Up to 90 g/hour

 

 

Protein

Protein helps grow and repair muscle tissue. Protein requirements range from 1.2-2.0 g/kg/day. For an optimal response, it’s best to 10 g of protein during the early recovery stage which is 0-2 hours post exercise. Muscle adaptation as a response to training can be enhanced by consuming 0.3 g/kg every 3-5 hours post exercise. Endurance athletes should aim for 1.2-1.7 g/k/day and resistance trainers should ingest 1.6-1.8 g/kg/day, bodybuilders may consume up to 2.0 g/kg/day (4). Sources of protein include poultry, meat, eggs, cheese, milk, soybeans, , chickpeas and pulses (legumes, lentils).

 

Protein

 

Fat

Many people may think that fat is bad, but fat is an essential part of our diet. Fat provides energy and is essential for the facilitation of fat-soluble vitamins (A, D, E and K). We should try to limit our intake of saturated fats (4) – those that are solid at room temperature (red meat, butter, palm and coconut oils, cheese). Saturated fats are problematic in terms of weight gain and heart disease risk, so we should limit these and include sources of essential fatty acids. Essential fatty acids are based on linoleic acid, the omega-6 group; and alpha-linolenic acid, omega-3 group (5). Essential fatty acids are found in fish and shellfish, leafy vegetables, olive oil, soya oil, walnuts, and various seeds such as flaxseed, chia, pumpkin, rapeseed, and hemp.

 

Fats

 

  1. Institute of Medicine. (2005). Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Retrieved from https://www.nap.edu/read/10490/chapter/1
  1. British Nutrition Foundation. (2009). Energy intake and expenditure. Retrieved from https://www.nutrition.org.uk/index.php?option=com_content&view=article&id=263:energy-intake-and-expenditure&catid=65&Itemid=199&showall=1&limitstart=
  1. Diabetes.co.uk. (2019). BMR Calculator. Retrieved from https://www.diabetes.co.uk/bmr-calculator.html
  2. American College of Sports Medicine. (2016). Nutrition and Athletic Performance. Medicine and Science in Sports and Exercise, 48(3), 543-568. doi:10.1249/MSS.0000000000000852
  1. Di Pasquale, M.G. (2009). The essentials of essential fatty acids. Journal of Dietary supplements, 6(2), 143-161. doi:10.1080/19390210902861841