The USDA Food Pyramid Says That Overeating and Inactivity Cause Us to Get Fat

The USDA food pyramid has advocated a low fat, high carbohydrate diet for all Americans for nearly thirty years. According to the nutritionists who crafted these guidelines, people get fat because they eat too much and/or because they are too sedentary.

This idea may seem extremely obvious and not worthy of debate, but the USDA food pyramid diet is based on a falsifiable scientific hypothesis just like any other. And good evidence should be able to confirm or refute it.

To understand where this 'obvious' idea comes from, we again harken back to the 1st law of thermodynamics:

Energy Stored in the Body = Calories In - Calories Out

The Caloric Balance Hypothesis tells us that excess calories cause us to get fat. When "Calories In" goes up and/or "Calories Out" goes down, the right side of the equation gets bigger. Therefore, the left side of the equation (how much energy we store -- ostensibly in the form of fat) also must get bigger. The fat tissue is allowed no say in the matter. It's all about calories. It has nothing to do with hormones or physiology. It purely has to do with the number of calories going into and out of the body.

Health authorities worldwide treat the idea that overeating and sedentary activity causes obesity as axiomatic. It is irrefutable fact, according to them. The USDA food pyramid recommendations to eat 300 grams of carbohydrates a day has nothing to do with why we are sick and fat.

For instance, consider this language from a recent study conducted by the Director of the World Health Organization's Collaborating Center for Obesity Prevention:

"The main reason that obesity has risen sharply in the United States in recent decades is predominantly because of overeating."[2]

An article at makes essentially the same point in support of the USDA food pyramid theory:

"Given the epidemic of obesity in this country, it's obvious that overeating is a significant problem. It's critical to find ways to turn down hunger, normalize our desire for food, feel full and satisfied, and deal with the situations that trigger us to mindlessly eat."[2]

Here is another quote from some researchers out of Cambridge in the UK:

"Obesity is ... determined by the long-term balance between energy intake and expenditure."[3]

The Caloric Balance Hypothesis -- which these experts all appear to subscribe to and which informed the construction of the USDA food pyramid -- makes crystal clear predictions about the real world. This theory tells us that a person who increases intake of calories and/or reduces the expenditure of calories will get fat.

Overfeeding (i.e. increasing "Calories In") will cause weight gain:

If it does, it would appear to confirm the Caloric Balance Hypothesis.

If it does NOT, it would appear to challenge/refute the hypothesis.

Activity restriction (i.e. decreasing "Calories Out") also will cause weight gain:

If it does, it would appear to confirm the Caloric Balance Hypothesis.

If it does NOT, it would appear to challenge/refute the hypothesis.

The caloric balance theory is extremely clear. Its predictions are testable. And if its predictions don't match up with reality, then it's the responsibility of those who advocate for that theory -- and for the USDA food pyramid -- to explain why they don't.

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1. Professor Boyd Swinburn as quoted in the article "US Obesity Due To Over Eating, Study" (May 11 2009)

2. Jennifer Nelson, M.S., R.D. and Katherine Zeratsky, R.D, "Overeating - What Causes it?" (May 30 2009)

3. Jebb SA, Moore MS. MRC Human Nutrition Research, Cambridge, United Kingdom "Contribution of a sedentary lifestyle and inactivity to the etiology of overweight and obesity: current evidence and research issues." Med Sci Sports Exerc. 1999 Nov;31(11 Suppl):S534-41.

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