The 2,000-calorie diet.

If you're one to scrutinize nutrition facts labels, you're familiar with this nutrition advice. And even if you've never looked at a label in your life, you've probably still heard the term.

It seems odd, though, right? That every single person — man, woman, child, adult short, tall, active, sedentary — should be aiming for the same number of calories per day.

It's so odd that you know better than to just assume that a 2,000-calorie diet is healthy for you, specifically.

Angela Snyder, wellness dietitian at Houston Methodist, is here to explain where the 2,000-calorie diet recommendation came from, who should follow it and what may work better for you instead.

Why a 2,000-calorie diet?

There's always a method to the madness, including in the case of the 2,000-calorie diet.

"It all started in the 1990s as a result of the Nutrition Labeling and Education Act. The goal was to ensure that food claims like "high fiber" and "low fat" be substantiated and consistent with FDA regulations — which is a great thing!" explains Snyder.

Food items can still come with some misleading claims (there's a whole science to reading food labels, by the way), but Snyder points out that enforcing these regulations helps prevent food manufacturers from blatantly lying about the healthfulness of food.

"What this meant, however, is that a way of measuring whether a food item has a lot of fiber or just a little bit of it, or a lot of fat or barely any was needed. That's where % Daily Value (%DV) comes in," says Snyder.

For instance, low fiber is anything that has 5% DV or less of dietary fiber per serving and high fiber is anything that has 20% DV or more of dietary fiber per serving.

Almost everyone has looked at % DV amounts, whether they know it or not. It's typically that right-most column on a nutrition facts labels. For example, a serving of liquid egg whites contains 10% DV of protein. Nice!

"The % DV has to be calculated from some standard daily calorie and nutrient intake that applies to as many people as possible, and this is where the 2,000-calorie diet finally comes into play," explains Snyder.

Where did the 2,000-calories diet come from?

Now we know: As part of the 1990 Nutrition Labeling and Education Act, a way of calculating % DV for certain nutrients was needed — which meant determining the standardized amount of food in peoples' daily diets.

"So, the USDA surveyed men and women, asking them to self-report how many calories they took in every day," says Snyder.

Women reported taking in between 1,600 and 2,200 calories per day and men reported between 2,000 and 3,000 calories per day. After some averaging, the 2,000-calorie diet was born.

So, yes, it's referred to as the 2,000-calorie diet. But Snyder points out it was never meant to be used as an actual "diet."

"When thinking about the 2,000-calorie diet, we need to look back at its original purpose. It was never meant to be a calorie guide for maintaining or losing weight. The intent was to use this value to calculate % DV, which, in turn, determines the nutrient content of food in order to help regulate food claims like low fat, low carb and high fiber," explains Snyder.

When is a 2,000-calorie diet too much?

The 2,000 calorie diet is based off of loosely averaged, self-reported data from men and women surveyed back in 1990. So, it probably comes as no surprise that it's probably not quite right for most people.

That's because a variety of things play into your calorie intake, including your:

• Age
• Gender
• Height and weight
• Level of physical activity
• Weight loss goals, if applicable
  
  

"Based on these personal factors, you may need fewer than 2,000 calories per day or you may even need more," says Snyder.

For instance, a 25-year-old woman of average height who exercises three times a week will need more calories per day than a shorter-than-average, 45-year-old mom who rarely finds the time to exercise.

"While the 25-year old woman may not be too far off from needing 2,000 calories per day, the busy mom may need several hundred calories less than that," says Snyder.

On the other hand, a 28-year-old man who's a bit shorter and can barely find time to work out between business trips, might need fewer calories than a 45-year-old dad of average height who works on his feet all day, chases his sons around when he's at home and makes time for a run a few times a week.

"The 28-year-old may actually need slightly less than 2,000 calories per day, while the dad likely needs several hundred more than that," says Snyder.

In addition, Snyder doesn't recommend following the % DV on a nutrition label if you're watching a particular nutrient in your diet, such as salt or saturated fat. This is because your personal nutrition goals are likely different from the 2,000-calorie standard used to calculate % DV.

"Instead, I recommend tracking the actual measurement. For example, for someone with high blood pressure who needs to reduce sodium, the 2,000-calorie diet % DV won't serve you well since the American Heart Association recommends limiting sodium to 1,500 mg or less. By looking at the actual milligrams of sodium per serving instead, you will be in much better shape when it comes to sticking to the recommended amount of sodium."

So how do you know how many calories you need per day?

"To determine how many calories you need per day, you'll need to calculate your basal metabolic rate, which is the amount of calories your body needs at rest. You'll then need to adjust this number based on how active you are," explains Snyder.

These calculations can lead to some pretty complex math, but you can also find a close estimate using a calorie calculator.

"However, first keep in mind that the values provided by online calculators are estimates. Second, some calculators will adjust your calorie count if you indicate that you're trying to lose weight. Any time you're trying to lose a significant amount of weight, it's best to first consult with your doctor or a dietitian about your weight-loss plan," adds Snyder.

Plus, Snyder points out that while eating a certain number of calories can help you maintain or lose weight, that doesn't mean a diet is "healthy."

"If you're eating the right amount of calories to meet your goals but choosing foods that provide little nutrition, such as refined carbs and added sugars, it's not a particularly healthy diet," warns Snyder. "A healthy diet that can help you lose or maintain weight is one that combines proper portioning with well-balanced meals. Ultimately, both quantity and quality of the calories you take in matter."