Heidi Smith, who owns and operates a nutrition communications and consulting practice out of the Health and Performance Centre at the University of Guelph, said she often finds when she begins working with competitive athletes that "it's very basic stuff that they're not doing properly that everybody needs to do, like drinking enough water, eating enough the night before and eating enough throughout the day."
"A lot of real simple tips can have huge impact on performance," she added.
The same philosophy can be transferred to the average person who wants to run, play tennis or do other recreational sports.
"We all have the same body functioning. We all have to have energy to burn. We need fuel."
When she starts working with anyone, she asks them to keep a food journal for a few days before their initial meeting, including meal timing.
It's important to eat every three to four hours to keep blood sugar levels stable and to keep carbohydrate stores up so that fat stores can be burned more effectively, said Smith, who did track, volleyball and tennis in university and had her own dreams of going to the Olympics.
If your body starts running out of its carbohydrate stores, you could end up hitting the wall, or bonking, and performance will suffer.
"It is unbelievable the increase in their energy and performance when they just eat and drink," Smith said. "It's extremely powerful."
But busy lifestyles can get in the way of eating whole foods, the right number of calories and getting enough hydration.
"You might rely on convenience food a little bit too much or forget to eat and then all of a sudden at the end of the day you're starving and you end up eating the things you shouldn't eat because you're so hungry and tired. So it happens to all of us," she said.
Smith, author of "Endurance for the Long Run: A Nutrition Handbook For Runners, Walkers and Active Individuals," advises clients to treat snacks and fluids just like their equipment and remember to pack a supply in their workout bag.
She says the average person needs to eat every three to four hours, but "the average Olympian needs to be eating about every two hours."
"They have such a fast metabolism because they have so much more muscle than the average person," she said. "Muscle burns calories so they almost have a furnace in them that's burning constantly so they have to keep fuelling that fire to keep it going.
"If you're an Olympic athlete or an aspiring athlete, you pretty much can't leave the house without food with you and drink as well. They've got to be eating as often as possible especially if they have long workouts."
Eating after a workout helps speed recovery.
Competitive swimmer Erin Stamp, 17, has worked with Smith on two different occasions.
In the initial consultation, when Stamp was in middle school, she learned she wasn't eating enough protein.
"Before I had a really scattered diet and ate randomly," Stamp said in a telephone interview from Guelph, Ont.
"We went through eating more consistently, not necessarily having a big breakfast, a big lunch and a big dinner but having a smaller breakfast and snacking throughout the day so you're not getting the big spike in energy and dropping but keeping a more constant level," said Stamp, who specializes in 100- and 200-metre breaststroke and 100 backstroke.
During the second and more recent consultation, she learned the value of drinking enough fluids, which Smith said many athletes overlook.
Performance drops when you get dehydrated.
A one per cent dehydration can cause a 10 per cent reduction in performance. For example, if you weigh 150 pounds and you lose one per cent of your hydration you have lost 750 grams (1 1/2 pounds) of fluid. That lowers your blood volume and your heart has to beat faster to get the same amount of oxygen to your muscles. A higher heart rate means you get tired faster, Smith said.
To prevent that loss, aim to drink 500 millilitres (two cups) to one litre (four cups) of water per hour of exercise. Water is fine for any workout under 90 minutes and a snack should be consumed two to three hours before starting exercise.
"If you're doing anything endurance then you really need to have some sort of carbohydrate at the 90-minute mark. It could be a sport drink, granola bar, crackers, fruit — every person is different as to what they can tolerate during exercise," Smith said.
Stamp, who just wrapped up high school, said she learned to take two water bottles to school and pack meals and snacks to get her through long days, with practices before and after school.
Before practice she eats fruit such as grapes or bananas and energy bars containing nuts and seeds made by her mother. After morning practice she might have a peanut butter and jam sandwich and chocolate milk or cereal with milk and a recovery shake or smoothie containing protein.
Taking Smith's advice "definitely" helped her performance, said Stamp, who has her sights set on competing in the Olympics in Rio de Janeiro in 2016. She plans to study human kinetics at the University of British Columbia in the fall.
Olympic veteran Clara Hughes is a self-proclaimed "Master of the Soups" and started a blog on her website in March to share some of her homemade favourites. Hughes of Glen Sutton, Que., is part of the four-member Canadian team competing in the road cycling competition at the London Games.
Smith applauded Hughes' choice.
"I think that's fabulous," she said, adding home cooks can add vegetables, grains and protein to the mix to make a balanced, satisfying snack for in between meals that is hydrating. It can also be poured into a vacuum flask and be sipped throughout the day. Soups can be prepared in big batches and frozen to save time.
For more information, visit Heidi Smith Nutrition, www.heidismithnutrition.com.