Learning from Nancy Clark

The dietitian who taught athletes to make peace with food—and perform better because of it

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The Story

When athletes came to Nancy Clark's office in the 1980s, she noticed something strange.

They weren't struggling because they didn't know what to eat. They were struggling because they were afraid of food.

"Good" foods. "Bad" foods. "Clean" eating. Guilt after every cookie.

Clark realized the problem wasn't nutrition knowledge—it was the relationship with eating itself.

Her solution was radical for the time: Stop labeling foods. Eat when you're hungry. Trust your body.

Four decades later, her Sports Nutrition Guidebook has sold over 600,000 copies and remains the standard text for sports dietitians worldwide.

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Who is Nancy Clark?

Clark has been a practicing sports dietitian for 40+ years, working with everyone from recreational joggers to professional athletes. She also ran marathons, trekked the Himalayas, and led cross-country bike tours—so she understands the real challenges athletes face.

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What ISP Students Learn

Lesson 1: Binge Eating Is a Body Problem, Not a Willpower Problem

"Binge eating is rarely a failure of willpower. It's a predictable physiological response to under-fueling."

Clark observed that athletes who restricted food during the day often binged uncontrollably at night. Coaches blamed lack of discipline. Clark blamed physics.

When you don't eat enough during the day, your body triggers a "famine response":

• Appetite hormones spike
• Metabolism slows to conserve energy
• Your brain screams for quick fuel (sugar, carbs)

The evening binge isn't weakness—it's your body demanding the fuel it was denied.

Clark's solution: Eat MORE during the day. Front-load your calories. The physiological drive to binge disappears.

What this means for young athletes: If you're "being good" all day and then eating everything at night, you're not weak. You're under-fueled. Eat breakfast.

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Lesson 2: There Are No "Bad" Foods

"There is no such thing as a 'bad' food, only an unbalanced diet."

Clark rejects the "good food/bad food" mentality that dominates modern diet culture.

When you forbid a food (cookies, bread, ice cream), it gains psychological power. Eventually you eat it. Then you feel guilty. Then you restrict harder. The cycle continues.

Her approach: "Legalize" all foods. Have a cookie if you want one. When it's not forbidden, it loses its power.

The 80/20 rule: If 80% of your diet is nutrient-dense whole foods, the other 20% can be whatever you enjoy. A cookie is just carbs and fat—not a moral failing.

What this means for young athletes: Treating pizza like poison creates a worse relationship with food than just... eating the pizza sometimes.

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Lesson 3: The Four Buckets Model

Clark noticed most athletes eat backwards:

• Small breakfast (300 calories)
• Light lunch (400 calories)
• Massive dinner + evening snacks (1,500+ calories)

This creates an energy deficit during the active hours and a surplus when you're doing nothing.

Her fix: Four equal "buckets" of calories throughout the day.

For a 2,400-calorie athlete:

What this means for young athletes: If you're exhausted at practice, look at what you ate before practice—not after.

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Lesson 4: Carbs Are Not the Enemy

While keto diets became trendy, Clark remained a defender of carbohydrates for athletes.

Her reasoning is biochemical: carbs are the only fuel source that can support high-intensity anaerobic efforts. Fat burns slowly. For a sprint, a lift, a fast break—you need glucose.

Athletes on low-carb diets often report "dead legs"—they can do slow, steady work, but they can't hit top speed.

"Why limit your ability to eat from the same pot as your friends and family?"

She also points out the social cost of restrictive diets. Food is community. Extreme restriction isolates you.

What this means for young athletes: If you're an explosive athlete (basketball, soccer, football), carbs aren't making you slow. They're making you fast.

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Key Takeaways

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How This Shows Up at ISP

Nancy Clark's philosophy shapes how we teach nutrition in the Bio Skill Tree:

• Fueling Consistency rewards eating regularly throughout the day—not skipping meals
• We never label foods as "good" or "bad" in challenges or content
• The "Four Buckets" model appears in meal timing education
• We explicitly address the dangers of chronic under-eating (RED-S) for female athletes

When ISP students learn about eating, they learn Clark's core message: your body is an ally, not an enemy. Work with it.

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Learn More

• How ISP Works →
• Life Skills Learning →
• Stacy Sims — Female Athletes →

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"The solution to overeating at night is not more willpower. It's more breakfast."

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