You'd have to look really hard to find a fitness coach, trainer, or dietitian that didn't "know" that cutting food intake by 3500 calories results in a one-pound loss. Cut 500 calories a day and after a year you'll have lost 52 pounds, right?

It's easy to find confirmation of that fact, too. It's estimated that at least 35,000 educational weight loss sites and probably a 100,000 more fitness sites make mention of the 3500-calorie rule.

Unfortunately, it turns out that the rule is a particularly good example of what Mark Twain meant when he wrote, "A lie can travel halfway around the world while the truth is putting on its shoes."

Only in this case, the lie has traveled around the world for the last 61 years or so while truth has been shacked up in a cheap hotel room with some floozy from Fresno and 1,000 cases of Thunderbird and can't even find its shoes, let alone put them on.

### The Real Number is Closer to 7000

To be fair, the 3500-calorie rule wasn't intended to be a lie, but it is completely false. It originated from researcher Max Wishnofsky, who, in 1958, burned a pound of fat in a calorimeter and saw that it gave up about 3500 kilocalorie's worth of energy.

And we all swallowed it, hook, line, and pork rind, without realizing that weight loss is governed by an altogether different mathematical formula and doesn't continue in a linear fashion.

It took a mathematician by the name of Kevin Hall, Ph.D., to figure out that over the course of the first year of a diet, people only lose about half of what's predicted. In effect, the true number of calories it takes to burn a pound of fat is closer to 7,000.

### Yes, Some People Will Be Bummed Out

Before you scream in anger and frustration, consider what Hall said: "I suppose some people will be bummed out, but we believe it's better to have an accurate assessment of what you might lose. That way you don't feel like a failure if you don't reach your goal."

The main problem with the 3500-calorie rule was it failed to take into consideration that the body pivots and adapts in a number of ways to minimize or even erase the effects of reduced caloric intake. It doesn't account for gender, either, or the fact that the metabolic rate drops as body weight decreases.

These observations go a long way in explaining the oft-heard complaint that "losing the last 5 pounds is the hardest."

### Sources

1. Kevin D. Hall, Steven B. Heymsfield, Joseph W. Kemnitz, Samuel Klein, Dale A. Schoeller, and John R. Speakman, " Energy balance and its components: implications for body weight regulation," Am J Clin Nutr. 2012 Apr; 95(4): 989–994.
2. Denise Webb, "Farewell to the 3500-Calorie Rule," Today's Dietitian, Vol. 26. No. 11, p. 36.