Calorie Deficit: How to Lose Weight

Weight loss is 80% diet and 20% exercise.  A sad but true fact.  Our diets are much more impactful on our health and weight than our activity level.  Don’t take this as a sign that you can stop exercising, because you can’t (more on that at a later date).  But you shouldn’t underestimate the power of a good diet.

The calories we eat determine our weight.  If we eat more calories than we need, we gain weight.  If we eat less calories than we need, we lose weight.  If we eat the exact amount of calories we need, our weight stays the same.  But how do you figure out how many calories you should be eating to maintain or lose weight?

As a disclaimer, I must mention that this is not exact.  The numbers mentioned will be estimates.  Calorie needs are based on age, gender, body size, activity level and genetics There is no way for me to give you an exact number.  If you are interested, head to a local gym that offers metabolic testing.  They can give you a better look into your individual needs.

But if you don’t want to spend the time and/or money on metabolic testing, these generalized numbers are a great place to start!

To figure out how many calories you need, check out the following chart:


Now these estimates are to maintain your current weight at your current activity level.

To lose weight, you need to have a deficit of 3500 calories (3500 calories = 1 lb).

So to lose 1 lb a week, you need to have a deficit of 500 calories a day.  To do this solely by diet, subtract 500 from the calorie count you got from the chart.

If you are adding additional exercise, you can subtract 300 on days you will be more active.

To lose 2 lbs a week, you will need a deficit of 7000 calories.

So, you will need a daily deficit of 1000 calories.  Now, it’s not a good (nor safe) idea to do this through diet alone.  So this is where exercise comes in to play.  You need to add more exercise into your daily routine to do this.  A food deficit of 500 and an exercise deficit of 500 (roughly 1 to 1.5 hours of exercise) will get you there.  This is intense.  It’s not for most people.  And that’s ok.

It may seem daunting to start with 1 lb a week.  It may seem like it will take you forever to reach your goals.  And that’s not true!  I DO NOT want you to start exercising constantly and starving yourself to lose weight.  This will only hurt you.

So, start with a caloric deficit of 300 to 700 calories a day.

How many calories are you eating in a day you ask?

Great question!

The best way to find this out is by keeping a food diary.  You can do this via online websites like sparkpeople, or apps like MyFitnessPal, or a good old fashion pen and piece of paper.

Write down everything you eat and drink.  Be as detailed as possible and don’t forget those few bites of your kids leftover sandwich or the two pretzels you took from the pantry while doing a walk by.  These all add up!  Write every little bit down – what you ate and how much you ate (or drank).

Next, calculate you calories.

You can find calories from food labels or online.

For food labels, check the serving size.  Sometimes the serving size is 7 chips, or 1/4 cup, or 1/2 package.  Compare that to what you ate and do a little math.  If you ate 14 chips, double the amount of calories listed on the label and write that down.  If you ate 1/4 package, half the amount of calories listed on the label and write that down.

Do this for everything you ate and then total it up.

Keep a diary for at least 3 days – and make sure at least one of those days is a weekend day (we tend to eat more on the weekends).  Now compare this to your calorie intake from the chart, and then your calorie deficit number (if applicable).  Are you eating too much?

If so, not to worry.  Look at the food choices you made during those 3 days.  Where could you have cut back?  Can you eat less pasta with your dinner?  Can you use less mayo or choose another low calorie condiment to replace it with?  Do you mindlessly snack too much?  Are you drinking too many calories?

Make some decisions on where to cut back and then be very conscious of your choices as you start lowering your calorie intake.  Keep up the food diary to show your progress (or lack of progress) so you know what changes need to be made.

This may sound like a lot of work but soon you’ll be in the habit of watching caloric intake and you won’t even have to keep a food diary!  So keep up the great work and watch your weight go down.

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