Four Fat-Loss Myths for Endurance Athletes

Despite their apparent leanness, many active people are still discontent with their body composition. Don't let these myths do you in.

by Nancy Clark

All too often, I hear seemingly lean athletes express extreme frustration with their inability to lose undesired bumps and bulges:

"Am I the only runner who has ever gained weight when training for a marathon?"

"Why does my husband lose weight when he starts going to the gym and I don't?"

"For all the exercise I do, I should be pencil-thin. Why can't I simply lose a few pounds?"

Clearly, weight loss is not simple and often includes debunking a few myths. 

Myth: You must exercise in order to lose body fat

To lose body fat, you must create a calorie deficit. You can create that deficit by:

1) exercising, which improves your overall health and fitness, or

2) eating fewer calories

Even injured athletes can lose fat, despite a lack of exercise. The complaint “I gained weight when I was injured because I couldn't exercise,” could more correctly be stated “I gained weight because I mindlessly overate for comfort and fun.”

Adding on exercise does not equate to losing body fat. In a 16-week study, untrained women (ages 18 to 34) built up to 40 minutes of hard cardio or weight lifting three days a week. They were told to not change their diet, and they saw no changes in body fat (1). Creating a calorie deficit by eating less food seems to be more effective than simply adding on exercise to try to lose weight.

Athletes who complain they “eat like a bird” but fail to lose body fat may simply be under-reporting their food intake. A survey of female marathoners indicated the fatter runners under-reported their food intake more than the leaner ones. Were they oblivious to how much they actually consumed? (2) Or were they too sedentary in the non-exercise hours of their day?

Myth: If you train for a marathon or triathlon, your body fat will melt away

Wishful thinking. If you are an endurance athlete who complains, “For all the exercise I do, I should be pencil-thin,” take a look at your 24-hour energy expenditure. Do you put most of your energy into exercising, but then tend to be quite sedentary the rest of the day as you recover from your tough workouts? Male endurance athletes who reported a seemingly low calorie intake did less spontaneous activity than their peers in the non-exercise parts of their day (4). You need to keep taking the stairs instead of the elevators, no matter how much you train. Again, you should eat according to your whole day's activity level, not according to how hard you trained that day.

Myth: The more you exercise, the more fat you will lose

Often, the more you exercise, the hungrier you get and 1) the more you will eat, or 2) the more you believe you “deserve” to eat for having survived the killer workout. Unfortunately, rewarding yourself with a 600-calorie cinnamon roll can quickly erase in a few minutes the 600-calorie deficit you generated during your workout.

The effects of exercise on weight loss are complex and unclear—and depend on the 24-hour picture. We know among people (ages 56-78) who participated in a vigorous walking program, their daily energy needs remained about the same despite adding an hour of exercise. How could that be? The participants napped more and were 62% less active the rest of their day (3). Be sure to pay attention to your whole day's activity level. One hour of exercise does not compensate for a sedentary lifestyle.

Myth: You should exercise six days a week to lose weight

Research suggests exercising four times a week might be better for weight control than six times a week. A study with sedentary women (ages 60 to 74) who built up to exercising for 40 minutes of cardio and weights suggests those who did four workouts a week burned about 225 additional calories in the other parts of their day because they felt energized. The group that trained six times a week complained the workouts not only took up too much time, but also left them feeling tired and droopy. They burned about 200 fewer calories in the non-exercise parts of their day (5). 

The bottom line

If you are exercising to lose weight, I encourage you to separate exercise and weight. Yes, you should exercise for health, fitness, stress relief, and most importantly, for enjoyment. (After all, the E in exercise stands for enjoyment!) If you exercise primarily to burn off calories, exercise will become punishment for having excess body fat. You'll eventually quit exercising—and that’s a bad idea.

Instead of focusing on exercise as the key to fat loss, pay more attention to your calorie intake. Knocking off just 100 calories a day from your evening snacks can theoretically result in 10 pounds a year of fat loss. One less cookie a day is simpler than it sounds.

References:

1. Poehlman, J Clin Endocrinol Metab 87(3):1004-9, 2002.

2. Edwards, Med Sci Sports Exer 25:1398, 1993

3. Goran, Am J Physiol 263:E950, 1992

4. Thompson, Med Sci Sports Exerc 27:347, 1995

5. Hunter, Med Sci Sports Exerc. 2013 Jan 30. [Epub ahead of print]

6. Donnelly, Arch Intern Med 163:1343, 2003

7. Janssen, Int J Sports Med, 10:S1,1989

8. Pietrobelli Int J Obes Relat Metab Disord 26:1339, 2002

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Nancy Clark, MS, RD CSSD