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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.
Robin
Hi I am a 42 year old type 1 diabetic. I weigh 159 pounds and from the calculator it appears I should eat about 2304 calories to maintain. I used light activity I’m a teacher. I also workout everyday and a good chunk of the time two times per day an hour each session I am not losing any weight and crave sweets. I honestly don’t know how to eat anymore been doing every diet since I was 20. I have celiac and PCOS to make it worse. I would love an actual diet plan of food I like to help me
Christel Oerum
You might benefit from working with an RD (Registered Dietitian) who can help you develop eating habits tailored to you. Some even take insurance. Look up Ben Tzeel and his team, they are diabetes and nutrition experts – https://www.yourdiabetesinsider.com/
Aashay
Hey, would like to understand this formula used.
Meaning why these set numbers have been used. Any link you could direct me to or help me understand it here?
Also, is there a name for this formula?
Christel Oerum
The formula is based on the method used by the International Sports Science Association
Liz
After you calculate the calories and complete the steps 1-5 how should you divide the carb, proteins and fat? I use my fitness pal I have my goals at 50% carbs, 30%fat and 20% protein does this sound right?
Christel Oerum
It depends on your goals and if you have any dietary restrictions but the USDA recommends a macronutrient distribution range for carbohydrate (45%-65% of energy), protein (10%-35% of energy), and fat (20%-35% of energy; limit saturated and trans fats)
ameenaerum
how we differentiate between saturated and transfats.
Christel Oerum
Most food labels have both listed or you can look the foods you eat most frequently up online
Kelly Sumpter
I’m 4″11 and weight 152 pounds. On an insulin pump and brittle type 1 diabetic. I went to 110 pounds just 6 years ago to 152 pounds!. I just turned 47, and NOTHING i do seems to help, only i keep gaining. I’m not sure if its my age, hormones or the amount of insulin i’m taking. I just keep GAINING. Any suggestions ?
Christel Oerum
It might help you to work with an RD who understands diabetes. Your endo might be able to refer you, and I can also recommend Ben Tzeel, who’s both an RD and live with diabetes. You can find him here: https://www.yourdiabetesinsider.com/
arielle m
my mother in late 40s weight is 145 height is about 5’9 just foudn out she has diabetes she smoked and is now taking medication did i do the math right her calorie intake is 1420.65144 ? im trying my best to learn more to help her please get back to me
Christel Oerum
I think you might have stopped at step 3, you still need steps 4 and 5 to get to the total calories. Based on just those two numbers I’d guess your mother would lose weight on a calorie intake that low and the question is whether she needs to?
Sarah
I have struggled with calorie calculators online and I can’t thank you enough for this formula!! I wanted to make sure I’m feeding my muscle gains and nourishing my body properly and this helps me immensely. Thanks!
Toni
Hi Christel,
Just wanted your opinion/advice about my situation: I am a 51 y/o Type 2 currenty taking 1000 mg Metformin 2x a day, Levemir 45 units in a.m., 15 in p.m. also Novolog 5-10 units w/meals or snacks. I am not a breakfast eater, but I snack until bedtime (midnight). I usually eat my first meal around 1pm. Second meal around 7:30-8 pm, and an hiur or two later I feel so ridiculously hungry and crave sweets after that last meal. I end up eating/snacking way too much just before I climb into bed. And I notice am gaining weight fast especially after being put on the insulin in September. What am doing wrong? Or what can I do right to stop these hunger pangs and cravings at night? Thanks for sharing your knowledge and expertise with us. Your posts give so much insight and are a wealth of information that is certainly appreciated because lots of doctors don’t have the answers or don’t have the time to give personalized information. So thank you for all your hard work!
Toni
Forgot to mention I am a female.
Christel Oerum
I would try adding in more food earlier in the day. Intermittent fasting works for some but others just end up feeling extremely hungry once the fast is broken and they end up overeating, which sounds similar to your experience. And if you do want to snack in the evening, do controlled portions and focus on veggies and protein.
The weight gain is because your body is finally able to absorb the calories you’re eating as you now have enough insulin on board. Dialing back your caloric intake should help with that
Kay C
I was glad to see this Post site to you. I’ve had questions for quite sometime and hope you might could offer some advice. My doctor’s don’t respond when asked (even my endocrinologist).
I have had type 1 diabetes since I as 24. I am 66. I was very thin and athletic thru age 30. I had a total hysterotomy at age 34. I bring that up only because it may exacerbate my problem.
I am very obese now. I take a lot of insulin, more than most. I’ve done may diets for 30 years. None were successful. I’ve been a “natural, good for you” eater for the most part. Veggies, occasional fruit, low carbs, water, and similar. I go out to eat once every 2 months. Hardly ever eat fast food.
Recently I started keto but was afraid to eat a lot of fat since I have high cholesterol and triglycerides. But I stayed on it religiously for 3 weeks and never entered ketosis. I had around 10% carbs daily. I did not lose 1 pound, as has always been.
If anything my friends and family say I don’t eat enough food, as has always been the case. I dont eat much meat so I drink 1 protein drink per day and eat beans, nuts, cheeses, eggs, occasional chicken, and seeds. For exercise I walk a mile daily and lift hand weights.
Do you have any ideas for my possible weight loss?
Christel Oerum
Hi Kay, my first question is whether the doctors keep an eye on your thyroid function. Thyroid disease is very common for people living with diabetes (https://diabetesstrong.com/thyroid-disease-diabetes/) and if not managed appropriately it can make weight management difficult.
If all of that is managed I’d suggest you work with a Registered Dietitian (RD) who understands diabetes. You can lose weight or gain weight on any diet, even the “healthy” ones but the key is to determine the right calorie balance for you. Our Fitness Editor is an RD and might be a good option for you. You can find him here https://www.yourdiabetesinsider.com/
Megan
Hi Christel,
I am 5’6, 178 lbs- trying to lose roughly 30 lbs. Do you recommend any vitamins or supplements for type 1 diabetics trying to lose weight/gain muscle?
Christel Oerum
I don’t recommend supplements, I don’t think they’re needed unless your blood work tells you that you’re deficient. That being said, for muscle building, I’d focus on getting adequate protein. More details on vitamins and diabetes here https://diabetesstrong.com/vitamins-and-diabetes/
David
1 am trying to drop considerable weight my weight is 281 and configuring protein intake at 1 g it would be 281g of protein a day what is the configuration for my carb intake and fats
Sue
I am 52, 5’3″, 315 lbs. Not active except job duties at a retail job. I did the math and just under 3000 calories seems like way too many. All my doctor’s have said 1200 cal.
Christel Oerum
I wouldn’t take nutrition advice from a primary care doctor unless that person also has a registered nutrition (RD) degree. The formula here calculates an estimated amount of calories and should be seen as a starting point. I would start by finding your maintenance calories and then slowly reduce them from there. And I can almost guarantee you that your maintenance is well above 1200 calories. It will take time and some patience to figure it out, alternatively you could start by cutting down on a snack or meal and see how your body reacts before making any more changes
Jenn
I’m a 36 y/o female who is 5’3” and currently weighs 187lbs. According to your calculations I should be eating 2444 calories a day to maintain and 1944 a day to lose weight. Is that correct? I feel like those numbers are so high and I’ll just continue to gain weight with that many calories a day.
Christel Oerum
Remember this formula is based on averages and should only be used as a starting point. It’s based on the method used by the International Sports Science Association but there are a few different ways of calculating your needs.
If you’re already eating 1900 calories daily and don’t see any progress you could try 1700-1800 for a while and see how you do