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How Many Calories Should a Person Eat in a Day: Why This is the Wrong Question to Ask

The epitome of health comes from a precise calculation of how many calories a person should eat in a day and then eating exactly that...right? Wrong! There are numerous problems with that assumption, and I will explain it all to you here.

calculator for calorie needs

Changing Calorie Needs

Our calorie needs are not static. They change from day to day based on our energy needs that day, and they change over the course of one's life due to metabolism changes. On a day you walk around the mall your calorie needs will be more than on the day you sit at your office desk. Older people need fewer calories than they did in their teen years. And certain illness states also change calorie needs.

All right, so what about the average? How many calories a day should a person eat on average at a particular point in time? For this query there are answers. There are research-backed calculations that are used to determine calorie needs. These take into account age, sex, weight, height, and activity level. You can ask a dietitian for a number based on these calculations.

Although these calculations exist and are fairly accurate for groups of people, individual needs can be similar or different than the group's average needs. To determine an individual's calorie needs, complex and expensive equipment are used. These machines can be found in some hospitals and is some research facilities. Knowing exact calorie needs can be helpful for people with certain illnesses and for use in research studies. Exact calorie needs are not particularly useful for a typical person, and I will explain why.

Why Knowing Your Exact Calorie Needs is Not Helpful

There is an important reason why knowing your exact calorie needs is fairly useless. The reason is that humans are not machines. You can't tell a human to eat a particular number of calories and then they will do exactly that. There are complex neurological and hormonal processes that increase or decrease the drive to eat. These processes are not always in tune with the person's calorie needs. A person can attempt to eat a prescribed number of calories, but eventually physiology will win over willpower.

An additional factor is that sometimes the calories a person actually needs are so low that it is unlikely for a person to feel satisfied from that amount of food. This can even be the case when those foods are optimized for nutrients that contribute to satiety. Knowing that low number of calories may only lead to more frustration.

How Many Calories Should a Person Eat in a Day

How many calories a person should eat in a day is a unique number for each person. There is no rule that can be applied to all people. Even research-based calculations are limited in their accuracy for a specific individual, despite them being accurate for groups on average. Remember that knowing even the most accurate answer to this question may not give you any practical information that will change how you eat.

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