8

How can an adult in robust health find out how many calories his daily intake needs to be?

I'm not asking for loss/gain of weight; simply to maintain my weight.

7

As an approximation, there exist several different equations for calculating a basal/resting metabolic rate. These are:

  • Harris-Benedict
  • Harris-Benedict revised
  • Cunningham
  • Katch-McCardle
  • Mifflin St. Jeor

Each of these takes various factors such as age, lean body mass, sex into account in varying emphases to come up with a basal, or resting metabolic rate. This rate is basically how many calories you would need on a daily basis to simply breathe in and out all day long. If you run through all of them and then average, you should come pretty close to your basic needs. There are many calculators already programmed on the internet with these formulas, or you can get them here at the wiki link.

Once you have that, then you can take a look at the various sites on the internet that have calorie expenditures for various activities such as housework, office work, weightlifting, running, really just about any activity. Most of these are again approximations, the best charts will account for height/weight/age/sex. Add those to your BMR, and you should be pretty close to a daily intake need.

Really, though, all you need to do is track your weight. Take note of any long term trends on the scale, and if you are gaining weight, cut back on calorie intake or food makeup (healthier vs. unhealthy). If you are losing too much weight, eat more. Don't be alarmed by daily fluctuations, you can vary quite a bit during a day. Best bet is to weigh yourself under the same conditions daily.

If you are lucky enough to have a college lab or similar that supports general testing for the public (You can occasionally get in on a kinesiology class testing phase where they need subjects), you can get exhaled gas analysis, and this can give you a very close estimate of calories burned during a specific activity. This is somewhat rare and/or costly to have done.

4

JohnP has already given the right answer for it, but here is a quick solution if you are not so much into all those calculations.

Amount of calories you should take everyday = Basal metabolic Rate over 24 hours X Physical Activity Level

Physical activity level for most people with sedentary lifestyle can be safely assumed to be 1.53 (a gross generalisation). So using 1.53 in the above formula, the caloric requirement comes down to

daily requirement in kcal/kg = (24 X 1.53 X wt in kg)

So for a 72 kg male, with no other co-morbidities with sedentary lifestyle who looks to maintain wait, the caloric requirement is 2644 kcals per day. If you have an active lifestyle, then replace 1.53 with 1.8 and then the formula becomes

daily requirement in kcal/kg = (24 X 1.8 X wt in kg)

Since PAL(physical activity level) varies from individual to individual, giving the same formula to everyone is not right. However, these are safe approximations. This page gives a table of approximate PALs.

http://www.ivyroses.com/HumanBiology/Nutrition/Physical-Activity-Level.php

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