POP QUIZ: You just went for a run. How many calories did you blast? Chances are your guess outpaces reality, to the tune of, say, a Frappuccino. Overestimating calorie burn is the Big Daddy of runners' weight-loss mistakes, says Lisa Ellis, M.S., R.D., a nutritionist in Westchester, New York. But it's not the only misstep. Sneaky slipups can derail the weight-loss efforts of even health-savvy runners. Here's how to avoid eight common mistakes. (While you're at it, learn the top nutrition myths to avoid, too.)
1. OOPS! Miscounting Calories
It's true that running eats up more calories than nearly any other activity: The average man burns 124 calories per mile and the average woman burns 105, which means a three-miler nets you a 315- to 372-calorie deficit. But you can easily overspend your calorie deficit with something as simple as a flavored latte and a chocolate-chip cookie.
Get a better estimate of your calorie burn with an online calculator (like this one on Runnersworld.com) or with a GPS watch that allows you to input your height, weight, and other stats. If you're prone to overindulging postrun, avoid blowing your calorie deficit by finding a couple "reward" foods with easily controllable portions, like bite-size cookies or single-serving chips.
2. OOPS! Skimping on Fat
Feeling virtuous with your dry toast, naked salads, and splash of watery skim milk in your coffee? Not so fast: Your body needs fat to absorb vitamins like A, D, E, and K, and to regulate hunger; fats are digested more slowly than carbs and protein, keeping hunger at bay longer. It's also believed that fat helps your body sense the appetite-regulating hormones ghrelin and leptin, says Ellis. A no-fat or very-low-fat diet leaves those hormones out of whack.
Fat should make up 20 to 30 percent of your daily calories. But avoid trans fats (in processed foods) and limit saturated fats (meat, dairy). Rely on mono- and polyunsaturated fats (olive oil, nuts, seeds, avocados, fish); these protect your heart and promote satiety. A recent study found that even the aroma of some fats, particularly olive oil, may prompt the release of satiety-inducing hormones.
Related: The Best Foods For Weight Loss
3. OOPS! Running on Empty
You may have heard this one: Hit the road without breakfast and your body will burn fat. But it doesn't work the way you'd hope (find out what happens to your body when you run on empty). Rather than seeking out fat immediately, your muscles first use carbs that have been stored in your muscles as glycogen, says Rachel Berman, R.D. When those stored carbs run out and your body starts to burn fat, your energy plummets, forcing you to slow down and burn fewer calories than if you had properly fueled up.
If you're heading out for 30 minutes or less on an easy run, you can skip a prerun snack, since you probably have enough glycogen to power you. But if you run longer or harder, you should have a 100- to 200-calorie snack about an hour before your run. Choose carbs and a bit of protein, such as a banana with peanut butter, and drink water to hydrate.
4. OOPS! Not Fueling Post-workout
After longer or tougher workouts, your muscles have gobbled up all the glycogen they needed, and now they're hungry. Thing is, you might not be; many runners find their appetite is suppressed just after working out. "But later, when your body settles in and 'realizes' its glycogen stores are low, you'll feel much hungrier," says Berman, leaving you prone to inhaling everything in sight.
Aim to refuel within an hour of tougher workouts to re-power your muscles and stave off hunger later. The American College of Sports Medicine recommends a 4-to-1 ratio of carbs to protein. Keep this snack to fewer than 200 calories. With 160 calories per cup, low-fat chocolate milk fits the bill nicely, providing the ideal mix of carbs and protein.
TRY THIS: 25 Snacks That Boost Workout Results
5. OOPS! GU Overdose
Addicted to midrun refueling? You may be piling on more calories than you need by overdependence on energy bars, gels, drinks, and shakes. "Calories from midrace fuels are dense, add up quickly, and usually don't do much to suppress hunger," says Berman.
For runs shorter than 60 minutes, skip the gels and sports drinks; water is fine. Go longer and you should consume 30 to 60 grams of carbs (one or two energy gels or 16 to 32 ounces of sports drink) per hour of exercise.
6. OOPS! Drowning in Calories
Calories in a cup count just as much as those on your plate. Alcohol is particularly sneaky: According to a 2012 report by the Centers for Disease Control, American adults consume an average of 100 calories a day from alcohol. Add in sweetened beverages like coffee, tea, soda, and juice, and you could be overdoing it big-time. Studies show that, in general, liquid carbs don't contribute to satiety the way solids do. That means if you down 200 calories at the bar, you won't compensate by eating 200 fewer calories at dinner.
Most of the liquid you drink should be calorie-free: water, seltzer, unsweetened tea. Remember that alcohol may trigger overeating as your inhibitions drop. "Moderate drinking means one a day for women, two for men," says Berman. "Cut calories by choosing light beer, wine, or liquor mixed with seltzer. Avoid frozen drinks, which are high in sugar."
7. OOPS! Rushing Results
Blame overblown weight-loss expectations on celeb-endorsed juice cleanses or reality shows like The Biggest Loser. But trying to change everything at once or reaching for TV-ready results is often overwhelming enough to cause you to abandon your weight-loss plan, says Berman. If you are dropping a pound to two pounds per week, that's a sustainable pace, she says.
Make small changes, one at a time. Try to eat a healthy breakfast every day, for example. Swap out chips for an apple at lunch. It's not sexy, but it works. Rather than zeroing in on the scale, reward yourself with a manicure or piece of gear as changes morph into habits. (Plus, follow these 10 Tips for Weight Loss That Lasts)
8. OOPS! Not Re-Evaluating
It's a physiological fact: Bigger bodies burn more calories, even at rest. That's why the more you have to lose, the quicker you'll see weight-loss results. But as you shed pounds, your body adjusts and, frustratingly, burns fewer calories (including while running). So what worked initially will need to be tweaked as you slim down.
Every time you lose 10 to 15 percent of your weight, readjust your daily calorie intake, says Berman. Find your new (smaller) needs using the Runner's World Daily Calories Calculator. Recalculate your exercise burn, too, since that also decreases as you slim down.