Who determined we need 2000 calories daily?

Last Friday, ABC’s “Nightline” discussed hidden calories and this started a discussion. Who determine that 2000 calories was what the average person needed? How was it determined? What level of activity does this support? This last question popped up when we discussed why people supposedly eat more. You’re told to eat 2000 calories, but work construction. You obviously burn more calories, but 2000 calories are insufficient, so you snack and eat more to make up for the loss.

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I don’t think any official body says that 2000 calories are a target for anyone. They’re an estimate of what many people, mostly women, do in fact get, and that makes a nice round number to draw percentages of.

I have the book Recommended Dietary Allowances, 10th edition. It spends a full chapter on Energy, which is caloric requirements, and has two pages of references. That’s far too complex to summarize, but one thing to note is that first they estimate REE or Resting Energy Expenditure. That was calculated to be 1750 for males and 1350 for females. The 2000 and 2500 figures that you normally see on nutritional information labels are approximations of multipliers for sedentary day activity.

Again, neither one are targets or suggestions. You are supposed to look at your own calorie consumption or energy expenditure and adjust the percentages accordingly. So if you’re working construction and eating and burning 3500 calories a day, then you need to bump your figures up by 75%

I agree that few people understand this and few people understand that the RDA of a nutrient is closer to the minimum you need to avoid having deficiencies rather than something to shoot for specifically. It doesn’t help that this definition holds better for vitamins and minerals than for proteins, fats, and carbohydrates, which shouldn’t be exceeded in the same way.

I’ve spent whole chapters of books myself trying to explain this so I know that it can’t be done properly in a paragraph and that most information about the whole process is bad. But nobody should be telling you to eat 2000 calories. That’s just a reference to make comparisons easier.

Yeah, 2000 calories would be what zookeepers who are keeping humans in an exhibit would be aiming for to keep them alive. Your own calorie intake is a very subjective, moving target. Anyone who is interested in losing or maintaining weight probably should be keeping a pretty close eye on their calories in and calories burned; otherwise I’d say the results are your proof - if you’re staying the same weight, you’re eating the right amount of calories to maintain that weight.