The Science of Sport is written by two exercise science PhDs with interests in cycling, running, swimming, etc. Their current feature is on weight loss. I had my two cents to offer on their calories in vs calories out discussion.
After attending a nutrition conference hosted by Nancy Clark, MS, RD, and Bill Evans, PhD, this past weekend, my theories of weight loss, especially as it relates to athletes, have been confirmed with research. In a nut shell (raw and unsalted - lol), here are the concepts:
- There are huge benefits of pre-exercise fuel. A 1999 study measured how long bikers could pedal until they reached exhaustion. With the addition of a 400 calorie pre-exercise meal eaten 3 hours before the workout, athletes biked 27 minutes longer. Another study had participants eat 5 minutes before exercise and results were similar. Those who had breakfast 4 hours before, then a snack 5 minutes before biking improved 20% during the last 15 minutes when compared to only water. A 10% improvement was seen with just the 5 minute snack. Lesson learned: eat before you workout. You can train your intestinal tract.
- Diet while you sleep - Front load calories by eating a larger, balanced breakfast and having multiple snacks throughout the day that contain carbs, healthy fats, and protein. Diet at dinner. This way, you can use the energy (calories) throughout the day for training and every day activities. Chances are, you will be able to control portions at dinner, make healthier food choices, and run/bike/swim faster and harder. If your goal is weight loss, you will lose weight this way! Have you ever found yourself trying to eat "healthy" or "less" by starting off the day with a light breakfast, eating a small lunch, and by the time dinner comes around (especially post-workout), you are ravenous and blow the healthy eating resolution. And then there is the post-dinner snack. I'm going to guess it is not Greek yogurt with fruit but more likely a bag of M&Ms...Front-load your calories for success and energy.
- Don't get too hungry. You will tend to crave sweets and overeat. This goes hand in hand with the above statement but more emphasis is placed on snacks. Most people need to eat every 3-4 hours for blood sugar balance and to keep the metabolism running smoothly. High performing athletes may need to eat every 2-3 hours. I already have been eating this way, but my goal for the week is to have a bigger breakfast and bigger snacks in hopes of having more energy on my run. I will blog about my experience and we can see how dinner is affected.
- Many athletes trying to lose weight, especially woman, end up undereating. Most female athletes calorie needs are around 2,000-2,400 calories depending on that day of activity and their body size. If instead they consume 1500 calories in attempt to lose weight, the body will switch over to starvation mode and conserve energy. Thanks to evolution, the body is programmed to be efficient with calorie burning; if enough isn't going in, the metabolism down regulates and holds on to everything it can. Moral of the story - eat to lose weight. Don't be afraid. It really works. Plus, what a great diet secret: eating = weight loss**.
- ***The saying a calorie is a calorie is a calorie is not true. After a workout, it is important to refuel within the first half hour. During this time, muscles are more responsive to insulin. We need insulin to help our cells take up glucose (to replenish glycogen reserves) and amino acids (from protein, for growth and repair). Therefore eating a balanced snack with the proposed 4:1 ratio is important. Nancy's suggested recovery snack is milk or chocolate milk. If you can tolerate the lactose, milk has a natural balance of carbs (in the form of lactose which is a natural sugar) and protein (8 grams per 8 ounce serving).
- Fat and weight gain go hand in hand and do not help with recovery. Studies show that it takes 5 times as many calories to produce the same amount of weight gain with mixed compared to a high fat diet. Next time you consider stopping at Wendy's after a long run, think about your actions. That high fat burger with cheese and frosty will not help you recover but will help you negate the effect of the workout. It will also affect your appetite for your next meal and you will not meet nutrient requirements. Thus, calories from fat are different from calories from protein and carbohydrates.
- Carbohydrate calories are not treated the same either. Research shows that lipogenesis (new fat production) does not form after glucose ingestion but fructose is stored as fat. That means high fructose corn syrup may be contributing to our country's obesity epidemic and our own waist line struggles. Scientists think it has something to do with the metabolism of fructose, which must first pass through the liver in order for it to be converted to glucose.
Lots of good stuff. For more good stuff, pick up Nancy's book. She was one of the first sports dietitian's in the field and an expert on the material.
Schabort, Noakes. Med Sci Sports Exer 31 (3):464, 1999.