FOOTBALLERS BODY FAT & NUTRITION FACTS
An individual’s body fat stores represent a lifetime history of the balance between energy intake and energy expenditure. Fat is the major energy store in the body, and is an efficient way to store excess energy for use in times of need. A player will perform best when the amount of body fat is within his or her individual optimum range. This will vary between individuals, and will also vary across a player’s career, so there is no single value that is ideal. If the body fat stores fall too low, health will suffer. If body fat stores are too high, the player will be slowed down by having to carry unnecessary additional weight.
It is important, therefore that players manage their food intake and energy output to achieve an optimum body size and body composition. Strategies for managing energy intake and energy balance Players should individually manage their energy stores of body fat, carbohydrate (muscle fuel) and protein (muscle mass) by managing intake and expenditure of these nutrients separately. These issues will be discussed in separate parts of this booklet.
Players should follow an eating plan that achieves their specific goals rather than relying on appetite to guide energy intake. Advice from a sports nutrition expert is often required to develop this plan. Players should have a number of separate bio-markers to monitor their progress in achieving each of their energy-related goals. Body weight is not a reliable or accurate indicator of energy balance. Monitoring body weight can be misleading, and the information can be misinterpreted. Monitoring of skinfold fat thicknesses across the season, especially when undertaken by a trained kinanthropometrist, can provide useful information about changes in body fat stores. Urinary ketones can provide a marker of inadequate carbohydrate intake.
Measurements of changes in muscle strength and endurance provide a useful biomarker of muscle development. Special concerns about restricting energy intake Although many players reduce their energy intake at times to assist with the loss of body weight and body fat, it is harmful to restrict energy intake below levels that interfere with healthy body function.
Energy availability = total dietary energy intake – energy used in daily activity/exercise There is evidence from recent research that when energy availability drops below a daily intake of 30 kcal (135 kJ) per kg fat-free mass (FFM), there are substantial impairments of metabolic and hormonal function, which affect performance, growth and health.
In females, one outcome of low energy availability is a disturbance of reproductive function and menstrual regularity.
Other problems are likely to occur in male players. Players requiring advice for weight loss or fat loss should seek guidance from a qualified sports nutrition expert such as a sports dietitian. If a reduction in body fat content is necessary, this should be achieved gradually.
Players can avoid potential problems by taking care to avoid excess weight gain in the off-season. Careful management of both diet and activity levels in the off-season and in the pre-season can help the player to reach his of her ideal weight and body fat level with minimal impact on health or performance.
To avoid irreversible skeletal damage, any female player with disruption of normal menstrual function should be referred without delay to a medical expert for investigation.
10 BODY FAT | NUTRITION FOR FOOTBALL Example of low energy availability 60 kg female with 20 % body fat = 48 kg FFM Daily energy intake is 1800 kcal (7560 kJ) Cost of daily exercise (1 h/d) = 500 kcal (2100 kJ) Energy availability = 1800-500 = 1300 kcal (5460 kJ) Energy availability = 1300/48 or 27 kcal/kg FFM (113 kJ per kg FFM)
FOOTBALLERS BODY FAT & NUTRITION FACTS
