The cornerstone of any good fitness plan is getting your diet right, and to do that, the first thing you need to do is to determine what your daily calorie needs are.
There are a lot of different online calculators you can use to find out how many calories you should eat per day. Some of them are ok, but most calorie calculators oversimplify by only using your age, weight, and gender (and perhaps BMI).
If you are a fitness nerd like me, you will probably want to know the correct scientific way of calculating what your daily calorie needs are.
It’s a very easy 5-step process. I have used my own data in the example below to show you how I work out what my daily calorie needs are.
How to calculate your daily calorie needs
You can calculate your daily “maintenance calories” by following these easy steps:
Step 1: Find your current body weight in kilograms (if you live in the US, just divide your current weight in pounds by 2.2 to get your weight in kilograms).
Step 2: Multiply your weight in kilograms by 0.9 if you are a woman or 1.0 if you are a man.
Step 3: Multiply by 24
Step 4: Multiply by your “Lean Factor” from the table below (read on to learn how to find your body fat percentage if you don’t know it)
Example using my stats: 61 kg (134.5 lbs.) x 0.9 (female) x 24 x 0.95 (20% body fat) = 1252
This number is called your Basal Metabolic Rate (BMR). It’s how many calories you would burn in a day if you just lay on the couch all day and did nothing.
To find out how many calories you actually burn in a day, you need to multiply with your “Activity Modifier” from the table below.
Step 5: Multiply by Activity Modifier
My daily calorie need would be: 1252 (my BMR) x 1.55 (Light Activity) = 1940 calories/day
Important: No matter what this formula says, never eat less than 1,200 calories per day on average without consulting your medical team first. A very low daily calorie intake can lead to a slower metabolism, hormonal problems, and a number of other medical issues.
How to find your body fat percentage
As you can see, calculating your daily calorie needs is actually pretty simple, as long as you know your body fat percentage. Most gyms should be able to measure that for you, or a trainer can give you a very good estimate just by looking.
You can also use a tape measure and this online calculator to estimate your body fat percentage. It’s not as accurate, but you really only need an approximate number, so it should be good enough.
If you want a more accurate number (and to track any changes), you can invest in a scale that measures body fat percentage (you can buy the one I use HERE). It’s only $27.99 so it’s a worthwhile investment if you want to track your weight and body fat percentage.
How to decide your activity factor
The main mistake people make when using this calculation is to overestimate their physical activity level.
Even though I live a very active lifestyle and work out almost every day, I still only use the “Light Activity” multiplier. And that may even be on the high side because I also spend a lot (too much) time in front of a computer.
The higher multipliers are for people who use their bodies almost constantly throughout the day and therefore need a lot of energy, like construction workers, pro athletes, etc.
If you are pretty fit and active, you should probably use the “Light” or “Very Light” multiplier. If you are just starting a fitness program, use the “Very Light” multiplier.
Now that you know how many calories you burn in a day, the next step is to decide if you want to lose or gain weight.
How many calories should you eat to lose weight?
If you are trying to lose weight, I recommend eating around 400-500 calories less than you burn daily. That calorie deficit should lead to a weight loss of about 1 pound per week, which is a very healthy and sustainable weight loss.
I know it can be tempting to lower your daily calorie intake more if you are trying to lose weight, but it’s not a good idea. When you lose weight quickly by restricting your calories, you also lose muscle mass, and the weight you lose is much more likely to come right back (as fat) as soon as you stop dieting.
Instead, add more physical activity to your daily routine. Even just 15-30 minutes of light to moderate exercise such as walking can burn calories, increase your metabolism, and help you reach your goal weight.
To learn more about healthy calorie deficits, read our guide Can Eating Too Little Make You Gain Weight?
How many calories should you eat to gain weight (muscle)?
If you want to gain muscle, start out at 500 calories/day more than your maintenance calories and see what happens. If you find that you are also putting on a little too much fat, decrease your calories slightly.
Just like weight loss, healthy weight gain should happen slowly. If you want to gain weight and add muscle mass without adding (much) fat, focus on eating a healthy diet, incorporate exercise (and especially resistance training) into your daily routine, and aim for a caloric intake that’s only slightly higher than your maintenance calories.
How accurate is this formula?
While this calorie calculator is quite accurate for most people, it is based on an “average” person and therefore isn’t perfect for everyone.
It doesn’t take differences in natural metabolism into account, so if you have a particularly high or low metabolism (for example because of thyroid disease), the result from this formula won’t be accurate.
Because your natural metabolism declines as you age, the formula also tends to underestimate how many calories teenagers need and overestimate the daily calorie requirements for people older than 60.
It’s also the most accurate for people who are close to the “average weight”. If the result of your calculation is that you need less than 1,400 daily calories or more than 2,500 daily calories to maintain your current weight, then it’s recommended that you talk to your doctor or dietitian before making any changes to your diet.
Frequently asked questions
There are roughly 3,500 calories in 1 pound of body fat. This means that, in principle, you will lose 1 pound per week with a calorie deficit of 500 calories/day (3,500 calories/week).
In reality, weight reduction is often a little slower than this as your body adjusts dynamically to any calorie reductions by lowering your metabolism.
It can be very hard to know how much you are actually eating without counting calories. Research shows that people eating in fast-food restaurants underestimate how many calories are in their meal by up to 500 calories.
You can use apps such as MyFitnessPal or Lifesum to track your daily calorie intake (and daily activity).
To ensure you reach your daily calorie targets, it’s also a good idea to follow a meal plan. You can either create your own or simply pick one from my meal plan library.
Stephanie
this makes NO SENSE to me according to these calculations my caloric intake should be 2,600 there NO WAY that is right. I used the highest body fat with the lowest activity and I am a fat kid this is crazy I saw a diet doc and he told me to shoot for 1250 a day
Christel Oerum
Remember this is a calculator that will calculate the average calorie need for the average person. The heavier you are, generally the higher is your maintenance calories. As mentioned in the post, we suggest the calculation is used as a starting point.
Since you’ve already seen a doctor I’d suggest you go by his/her recommendation
Cathy Morgan
help! i have been following along the lines of this for the past 6 months, I am disabled so i have limited mobility issues. (pt twice a week) and according to calculations i should be eating appx 2000 cal per day. I am eating roughly about 800 to 1000. my sugar numbers are stable and so unfortunately is my weight. any other ideas i can investigate? i really need to lose about 50 lbs. thanks
Christel Oerum
Hi Cathy,
The first step is to check your diet and see if you’re actually eating that low-calories. That means weighing everything out, also the sips and nibbles. If you’re already doing that I’d recommend a few things.
1. Get your blood work done to test for hormone imbalances
2. If you’ve been on very low calories for a long time you might need a diet break. Your body can adjust to a low-calorie level
3. You might need more time. If you’ve seen no results in 6 months then obviously something needs to change, but if it’s only been a few weeks, you might just need more time
More ideas for When The Weight Won’t Budge HERE
Victor
Hi Christel, sorry. May I know the name of the equation being used to calculate the daily calorie intake?
Christel Oerum
Hi Victor, this is the method used by the International Sports Science Association. There are other ways to calculate daily calorie needs, but we think this is the most accurate method that’s still relatively easy to do yourself.
Fazil RF
Hi Crishtel,
I’ve lean body with chest fat, can you help me to get rid of chest fat
Christel Oerum
what you are referring to is called “spot reduction” and is unfortunately not possible. You’ll have to reduce your overall body fat and fat accumulated over the chest will also come down. If you have a lot and not much fat other places you can also talk with your doctor and get an assessment of your hormone levels (estrogen specifically).
Jana
Hey, this maybe sounds like a dumb question… but what if I want to loose fat and build some muscles at the same time? Should I decrease or increase my Calorie intake? Or should I just leave it at what my body can burn in a day?
Just for reference, I do a approximately 30-40 Minute workout every day my body doesnt ache (since I’m just getting started and trying to figure out stuff that means about 2-3 times a week right now).
Christel Oerum
Doing both at the same time can be tricky. Your calorie level will also depend on how much fat you have to lose. If you have a lot you can be a little more aggressive with your calorie surplus. I’d start with a neutral calorie intake and adjust after 3-4 weeks depending on how your body reacts. I know that’s not a super precise answer, but it will really depend on your body
Glenn Nordal
I’m a Type 1 diabetic fighting belly fat , I take 30 units of Toujeo morning and night , and 10-12 units of NovoRapid whenever I eat , or when necessary I will take a smaller dose . I walk daily and eat pretty well but cannot seem to lose any weight , I’m 5’10 and 205 lbs need to lose at least 20 lbs but nothing seems to work . My doctors , yes doctors , have me pegged at a 1.5 diabetic whose blood sugar rarely goes low , in fact I can go 24 hours without eating and still be high or normal blood sugar levels . I’m told insulin makes you store fat yet my doctors tell me in increase my insulin and lose weight which is nearly impossible , any suggestions ?
Christel Oerum
Insulin in itself will not make you gain weight (then all people who inject insulin would be overweight). Being in a calorie surplus and taking your insulin will however make you gain weight. I’ve found that injecting insulin can make it harder to lose weight but with a consistent calorie deficit and good blood glucose management it can definitely be done.
If you’re not losing weight I’d suggest you track all calories for a while (including liquid), including weekends, and then subtract 200-500 daily. Be very diligent with managing your blood sugars and utilize exercise to help reduce BG levels when you can.
And remember it takes time, some don’t start to see results until they have been consistent for up to a month
Nancy
Check on fb for the type 2 diabetes support group. They have some amazing testimonials from using the groups low carb/high fat diet. It is quite intriguing.
MaggieMay
Hi there. I work in an office so I am sitting mostly during the day. I do however go to the gym (HIIT workout) four times a week for 45mins each, walk/bike around after work. To calculate my daily calorie intake, what active level am I at?
Thanks.
Christel Oerum
I would use the lowest and see how that works out. I always find that the higher activity levels work best for people who have active jobs.
James
Hi,
Just wondering what scientific rational you use to base these calculations on?
Thanks
Tobias Oerum
Hi James, this is the method used by the International Sports Science Association. There are other ways to calculate daily calorie needs, but we think this is the most accurate method that’s still relatively easy to do yourself.
Kyle
Hi,
Just wondering when I should be taking insulin for these meals? Should it be every 2nd meal? Also what is the time frame/gap between each meal? I am on a pen injected insulin and not s pump and don’t want to overlap my insulin. Should I take insulin at breakfast, lunch, and dinner and simply eat the other meals without taking insulin?
Thanks again btw, extremely helpful diet plan that comes from a diabetic themselves!
Christel Oerum
I can tell you what I do. I take insulin whenever I need (unless I’m running low or have too much insulin on board already). The goal is to match your insulin with your food and hormones so that you stay in range. So if you stay in range without insulin, then don’t dose.
Stacking (taking two or more doses close to each other) can be very dangerous if you don’t know what you’re doing. I know the technique so I can do it safely but you have to learn it. Talk to your doctor about how you dose for meals closer to each other if you need it. It comes down to knowing how much insulin you have in your body already, your BG, your activity level, carb and correction factor. That formula looks daunting but that’s basically what insulin pumps use to calculate doses or if you use an app based calculator (like I do) such as RapidCalc
Steve
If you’re taking insulin for breakfast, lunch and dinner, what “other meals” do you have exactly?
Christel Oerum
Some of us also eat snacks
Alisha
I have just used your calculator and minus the 500 for weight-loss puts me at 977.44 cals a day ? yesterday I was so strict on eating and was still about 1432… Any suggestions or even what exercise to burn 500 cals
Christel Oerum
Hi Alisha,
In general, I don’t recommend going below 1200 calories on average per day. I’d suggest that you track your meals, snacks and calorie drinks throughout that day, that way you can keep track as you go. Do that for a while and then add in a minimum of 20-min of activity a day. Choose an activity you enjoy and focus less on how many calories you burn during. Why do I say that, well exercise like resistance training and HIIT will also have an afterburn and you need to choose an activity you can stick with. This is not a sprint but a long journey. Patience will be key
Shamara
Good Morning!
So, glad I came across your website! I’ve found a lot of useful information already to incorporate into my lifestyle for sustainable weight loss. My problem area however, is my stomach. Do you have any suggestions for a T1 diabetic that is on an insulin pump on good ways to loss belly fat?
Christel Oerum
Unfortunately, spot reduction is not really possible. It will be a question of reducing your overall body fat and depending on how you’re built, your belly fat might be the last to go. Other issues that can look like belly fat can be bloating and/or water retention. Should you struggle with either it could be an idea to look into and resolve the underlying issues for that