Breaking Down the 3,500 Calorie Myth: How We Lose Weight Matters More Than How Much

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When Pursuing Your Racing Weight, Focus on the Process, Not on the Outcome.

This article is from Racing Weight, Matt Fitzgerald’s proven weight-management program designed specifically for endurance athletes. 

One of the oldest myths of weight loss has been laid to rest.

Since the late 1950s, dieters have been taught that for every 3,500 fewer calories they eat than they burn, they will lose one pound of body weight. This dictum was based on research showing that a pound of human flesh contains about 3,500 calories of energy, and it predicted that if a person adjust her activity and or dietary habits to create an energy deficit of 500 calories per day, she will lose 1 pound per week, every week, indefinitely.

This prediction has never borne out in research. When scientists carefully control the diet and activity level of subjects, they usually lose only about half the weight that the 3,500-calorie rule predicts. The main reason is that the body adapts to caloric deficits in ways that progressively reduce their effect over time. In principle, therefore, the only way to lose weight at a steady rate over a long period of time is to progressively increase your activity level and/or reduce your food intake. But this is neither practical nor wise, because energy deficits exceeding 500 calories per day generate more muscle loss than fat loss, leave the body underfueled for exercise, carry a risk of nutrient deficiencies, reduce bone mineral density, and exacerbate metabolic adaptation to energy shortfalls.

[RELATED: The Dangers of Underfueling]

The death of the 3,500-calorie myth points to an important principle of effective weight loss: It’s better to focus on process (how you lose weight) than on outcome (how much weight you lose or how quickly you lose it).

Racing Weight elite runners body fat percentage
Elite runners get lean from running, not dieting.


The simple truth is that it is difficult to predict how much weight you will lose on any given diet plan. Nor is it a good idea to chose a diet plan on the basis of a particular weight-loss goal.

Healthy eating habits are universal. Whether you are 50 pounds overweight, 10 pounds overweight, or already at an ideal weight, you will get the best long-term results from the same core set of eating habits and from combining these with vigorous daily exercise. In today’s food and eating environment, most people find these habits difficult to adopt and sustain.

In fact, focusing too much on results makes it even harder to achieve them. This was shown in a 2012 study conducted by psychologists at the University of Zurich and published in Psychology & Health. The subjects were 126 overweight women involved in a 6-month weight-loss program. The researchers found that those who were more focused on the process of acquiring and practicing healthy eating habits experienced fewer dietary lapses and lost more weight compared to those who were more outcome focused.

Racing Weight bathroom scale
Do check the scale–but just about once a week.

For these reasons, anyone seeking to lose weight or maintain his current healthy weight should concentrate on the process of adopting and sustaining these habits and trust that they will lead to the best possible outcome.

Endurance athletes are no exception. If you’ve read Racing Weight, you might find this statement surprising. After all, the book includes a formula that athletes can use to estimate their optimal racing weight, which is the ultimate bodyweight outcome goal for athletes. But there is a reason this tool is called an estimator, not a calculator.

As I take pains to explain in Racing Weight, there is no way to predict your optimal racing weight with perfect accuracy. The only way to determine it is to attain it, and the only way to attain it is to eat and train your way to the highest level of race-specific fitness possible.

There are six core habits to weight loss for athletes: maintaining high diet quality, balancing energy sources appropriately, managing appetite, self-monitoring, nutrient timing, and adhering to the “80/20 Rule” of training intensity distribution. These six habits apply to all athletes. These habits, not your target weight, should be your major focus. If they are, the numbers will work themselves out, as they always have.

Racing Weight is a proven weight-management program designed specifically for endurance athletes. Revealing the latest research and drawing from the best practices of elite athletes, coach and nutritionist Matt Fitzgerald lays out six easy steps to help cyclists, triathletes, and runners lose weight without harming their training.

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    Racing Weight, 2nd Ed.

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