How many calories do I need to eat every day to lose weight?
This is a common question on our lovely forum. So I figured I'd write a thread about it - if it's any use / helps people, maybe it could get stickied. NOTE: if you have health problems that affect your mobility or metabolism, then I advise you seek medical advise rather than following this guide.
The fast answer:
If you don't want to read the long version of the answer - go off to myfitnesspal.com and that site will work it out for you!
Note that MFP.com gives you NET calorie intake per day - you are encouraged to eat whatever calories you burn through exercise BACK if you use that number.
My Slightly-More-In-Depth Guide - the longer answer:
1.Work out your BMI here, if you don't know it. If you've input your weight into your Minimins profile, you probably know your BMI (as it's under your details when you make a post!).
2. Work out your BMR
Your BMR (Basic Metabolic Rate) is basically how many calories your body burns by just existing - by doing basically, nothing. If you lay in bed all day and did not move, this is how many calories your body would burn. If you ate this many calories, and did not move all day, you would maintain your current weight.
3. Remember this figure and use it in the Harris-Benedict Equation. This equation works out how many calories you specifically, according to your activity level, burn every day. The more active you are, the more calories you burn (duh!), and therefore the equation is different for the woman who sits at her desk all day and does no exercise, than for the lady who runs a 5k 6 times a week. The number you get at the end of the Harris Benedict Equation is the number of calories you need to eat daily to maintain your weight, at this lifestyle.
4. But I don't want to maintain! Exactly, this is why we create a calorie deficit. To lose a pound, you need to shave off 3500 calories from somewhere, this equates to 500 calories a day, to lose 1lb in a week. You shouldn't aim to lose more than around 2lbs a week unless you are very overweight - this is because when you lose more than 2lbs a week, you are not just losing fat, but water, and more importantly, the good stuff - muscle.
Muscle is great because it increases your metabolism(the rate at which you burn fat!) and the heart is also a muscle! You don't want to lose it!
Here are the recommended daily deficits, depending on BMI (which we worked out in Step 1, remember!):
Generally someone with a BMI over 32 can do a 1000 calorie a day (2 lbs a week) deficit
With a BMI of 30 to 32 a deficit of 750 calories is generally correct (about 1.5 lbs a week)
With a BMI of 28 to 30 a deficit of 500 calories is about right (about 1 lb a week)
With a BMI of 26 to 28 a deficit of about 300 calories is perfect (about 1/2 lb a week).
So, if you had a BMI of 28, and the Harris Benedict Equation gives you 2000 calories a day to maintain, you'd make your deficit of 500 calories a day, and consume 1500 calories daily / 10500 a week(and wouldn't consume your exercise calories on top of it - they're accounted for in the Equation!). Do not ever go below 1200 calories a day if you are a woman, this is dangerous and creating too large a deficit.
Oh my goodness, that was all a bit complicated! Help!
Here are a couple of examples of following the steps in case you're stuck.
CASE 1- ME
1. My BMI. I'm 5'0'', female, and weigh 146.5lbs. The BMI calculator tells me my BMI is 28.6.
2. My BMR. I input my height, weight, gender and age (26) into the BMR calculator, and it gives me 1456.775.
3. The Harris Benedict Equation.
I exercise roughly 5 times a week, so I'm "moderately active".
So I calculate my BMR by 1.55.
1456.755 x 1.55 = 2257.9.
I'll round it up and say 2258.
I need 2258 calories a day to maintain my weight, with the amount of exercise I do.
4. With my BMI, I can run a healthy deficit of 500 calories a day.
2258-500 = 1758 calories a day / 12306 calories a week. I do NOT eat any exercise calories back this way. This is what I have.
CASE 2- WE'LL CALL HER ANN
1. Ann's BMI. She's 5'6" and 200lbs, putting her BMI at 32.3.
2. Ann's BMR. Ann is 35 years old. Therefore her BMR (using the above figures) is 1670.7.
3. Harris-Benedict Equation.
Let's say Ann plays tennis twice a week. This puts her as "lightly active".
So we multiply Ann's BMR by 1.375.
1670.7 x 1.375 = 2297 calories (rounded).
4. With Ann's BMI, she can run a healthy defecit of 1000 cals a day IF she wants to lose 2lbs a week (she can run 500 if she wants to lose 1lb, 250 if 0.5, 750 if she wants to lose 1.5 etc.) she can eat 1375 calories a day / 9625 a week. This is what she has, she does not eat any extra to compensate for the exercise done.
Ann says - WAIT A MINUTE! On the days I play tennis, I get really hungry! Therefore, Anne could have 1200 calories a day (the minimum recommended for women) on the 5 days a week she does not exercise. This means that on those 5 days she has consumed 5 x 1200 = 6000 calories. Now, she has 9625 - 600 = 3625 left from her weekly total, so on the days she plays tennis, she could have 3625 / 2 = 1812 calories.
If she finds she's getting too hungry on her inactive days, she could have 1300 on the 5 "inactive" days, and then 9625 - (1300 x 5) = 3125 can be divided between the two active days. Therefore she could eat 1563 (rounded up) calories on those days she plays tennis, and 1300 on days she doesn't.
Again - this information is not accounting for people with metabolic conditions or specific health issues that may impede weight loss.
Hope this information helps! Again, if anybody is stuck, the best way to work out your calorie allowance is to go to myfitnesspal.com and input your details.