Just over a week into the Olympics, most of those watching the events have had at least one moment of awe about the feats of athleticism on display. We all know that competing at the Olympics is the end product of years of training, but how much fuel do elite athletes need?
The energy needs of athletes vary depending on their overall body composition and performance goals, as well as day-to-day training type, duration and intensity. This means energy intake is the one dietary factor that tends to differ most between sports.
An artistic gymnast, for instance, needs to be relatively light but muscular – to work against gravity and perform aerial twists. In Olympic weightlifting, weight categories for competition range from 48kg for women to 105kg-plus for men. This wide range in weight and size results in large differences in the amount of fuel that individual sportspeople need.
In endurance sports, such as marathon, triathlon, road cycling and the longer distances in swimming, the amount of training and competition can result in estimated energy requirements in excess of 20 MJ/day.
That’s about the equivalent of approximately eight slices of bread; two cups of porridge; six pieces of fruit; 200g cooked steak and 200g cooked chicken; two cups cooked rice; two large potatoes; five cups of green and yellow vegetables; 30g nuts; 60g cheese; and 1.5L of milk
Training programs typically vary in duration, intensity and volume over a competition cycle, and this “periodisation” changes the amount of energy needed.
Athletes who chronically restrict food intake (to stay lean, for instance, or to “weigh in” for events) are more likely to experience fatigue, nutrient deficiencies and loss of lean mass and strength. They also risk developing longer-term health issues, such as impaired cardiovascular and bone health, as well as decreased immunity.
The International Olympic Committee has produced a consensus statement on the risks of relative energy deficiency in sport in response to these detrimental effects to help make athletes and coaches aware of this important issue.
How much to eat
But what about the composition of athletes' diet? Is it more important to get protein or carbs?REUTERS/Suzanne Plunkett
Athletes need more protein than sedentary people and recommended requirements are approximately 1.2 to 2g protein per kilogram of body weight per day. So for a rower weighing about 85kg this could be up to 170g of protein a day.
We usually teach athletes about servings of different foods that contain 10g of protein, such as two small eggs; 30g reduced fat cheese; 50g grilled fish; 200g reduced fat yoghurt; four slices of bread; and 35g lean beef or lamb. The protein requirements for athletes are easily achieved as most people in developed countries typically eat close to this amount of protein each day.
Carbohydrate requirements vary depending on the training type, intensity and volume. Most athletes need between three and seven grams per kg of body weight every day.
Endurance athletes, who may be training or competing three or more hours a day, are generally recommended to consume between 6-10g of carbohydrate per kg body weight every day. But this can go up to 12g per kg body weight during more extreme, strenuous training or competition (more than five hours a day).
To support recovery, timing some protein and carbohydrate intake around training is beneficial.
Consuming around 20g of protein (often milk or dairy sources are used) in the immediate post-exercise period is beneficial for supporting increased synthesis or manufacture of protein. This can help athletes gain lean mass and strength.
More rapid restoration of muscle glycogen (the stored form of carbohydrate) can be supported by including 1 to 1.2g carbohydrate per kg per hour for the first four hours after intense (glycogen-depleting) exercise. It’s particularly important if there are repeated, strenuous training sessions over the day or there’s a need for fast recovery (during a strenuous week of repeated competition games or events, for instance).
Eating for gold
Athletes competing at the Rio Games, who are living in the Olympic village, eat at a temporary dining facility that can cater for 4,000 to 5,000 people in one seating. It’s open 24 hours a day and employs hundreds of managers, chefs and service staff.REUTERS/David Gray
The menu caters for athletes from a range of competition events – and thus with different energy and nutrient requirements – as well as different cultural and religious beliefs (vegetarian food for Hindus, for instance, or halal meals for Muslims) and food preferences (vegan or lactose-free, for example).
Speciality chefs cater for different regions and there’s usually a focus on the style of eating from the host country. In Rio, for example, there’s a strong emphasis on South American and Brazilian dishes, particularly desserts.
As well as the dining hall, there is a range of other food options where athletes can “grab and go” or eat in a more relaxed environment. Food is also provided for travel to the various competition venues and at the venues themselves.
The complexity of providing food for a major competition has evolved over time in response to increasing numbers of athletes, countries and competition events.
There’s evidence suggesting that more athletes are following different types of dietary regimens, but we don’t know if this is simply a trend or for medical reasons. In particular, requests for gluten-free items have been increasing.
Sports dietitians work with Olympic caterers to ensure the menu accommodates all kinds of diets and can guide athletes with their food choices in the dining hall.
Authors: Helen O'Connor, Senior Lecturer in Nutrition, University of Sydney