Part 1: The tortoise or the hare?
Many cyclists are confused about what the optimal exercise intensity is for weight loss.
Current folk-wisdom has it that low-intensity activity is best for fat-burning, because fat is the primary fuel for such slower-paced exercise.
While the latter part of this statement is true, a study conducted at Georgia State University shows that weight loss depends on the total number of calories burned during a workout, not whether those calories came from carbohydrates or fat.
To illustrate, consider George and Jennifer. They're both trying to shed their spare tires by following moderately high carbohydrate diets.
For our purposes, assume that their body weights, calorie intakes and fitness level are equal.
George is an advocate of low-intensity exercise and cycles easily for two hours using 600 calories with over half of those calories coming from fat.
Jennifer cycles at high intensity for only one hour also burning 600 calories, mostly from carbohydrates.
During the rest of the day, however, George uses more carbohydrates as fuel for sleeping, sitting and walking around as a consequence of his slower workout.
Jennifer, uses more of her limited carbohydrate supply for exercise, and so now her body taps into abundant fat stores to fuel her daily activities.
After a few weeks of this routine, both will have lost the same amount of body fat. Note, however, that if Jennifer exercises as long as George does, but at her high intensity pace, she'd come out ahead in terms of fat loss.
The bottom line? The total number of calories expended per day is what counts. If you have time limitations and want to lose weight, ride harder.
Part 2: Diet—pass the pasta or the olive oil?
The importance of carbohydrates for athletes has been virtually undisputed in recent years, at least until the publication of The Zone, by Barry Sears, which advocates a diet that's 40 percent carbohydrates, 30 percent protein, and 30 percent fat (40/30/30).
By contrast, the generally accepted percentages for an athlete's diet are 60/15/25.
The book's recommended diet claims to provide benefits such as weight loss and improved physical performance. However, most scientists are skeptical the research simply doesn't support such outcomes.
Research does show that weight loss occurs at similar rates when subjects are fed high or low carbohydrate diets as long as their diets contain an equal number of calories.
However, a recent Cornell University study shows that a higher fat diet may lead to increased calorie consumption overall:
Volunteers ate as much as they wanted of either higher fat or lower fat diets for 11 weeks. Menus for the two diets were identical and included similar tasting higher and lower fat versions of the same foods.
On the lower-fat diet, subjects ate fewer calories and lost an average of 5.5 pounds double the loss of those subjects on the higher-fat diet.
So, just as total calorie expenditure was the bottom line for exercise intensity, total calories eaten is the bottom line for your diet.
By limiting (not eliminating) dietary fat, you can cut calories without cutting nutrition. You'll also maintain the carbohydrates needed to fuel high-intensity exercise and keep the volume of food consumed high enough to prevent hunger pangs.
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