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How To Calculate A Calorie Deficit For Weight Loss | Nutritionist Explains | Myprotein
Jan 30, 2025
What is a calorie deficit and how do you go about calculating one? Our expert nutritionist explains all.
When it comes to losing weight, there are hundreds of different diets and exercise plans out there, all claiming to be the magic solution. But when it comes down to it, the one essential thing you need to shed those pounds is, in theory, incredibly simple — and that's achieving a calorie deficit.
But what actually is a calorie deficit and how do you calculate one?
That's where qualified nutritionist and PhD researcher, Richie Kirwan, comes in with all the science-backed facts to make your fitness journey easier. Find out everything you need to know about calorie deficits right here.
Find Richie on Instagram: @be_more_nutrition
Check out our BMR & TDEE calculator here: https://bit.ly/3AylX05
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0:00
you just need a calorie deficit mate
0:01
while true it's also one of the most
0:04
reductive things you can tell someone
0:05
who's trying to lose body fat that said
0:08
understanding how to calculate one is
0:10
useful so let's talk about
0:12
that how's it going guys my name is
0:14
Richie Kerwin and today we're going to
0:16
talk about what a calorie deficit is why
0:19
it's important for weight loss and also
0:21
why knowing how to calculate one isn't
0:23
all that helpful on its own let's get
0:26
started every single diet that has
0:28
helped people to lose body fat in the
0:30
history of humankind works on the exact
0:33
same principle by helping you eat fewer
0:35
calories than you burn this is what's
0:38
known as a calorie deficit so if you eat
0:41
2,000 calories a day and your weight
0:43
stays the same that means you're burning
0:45
2,000 calories too that's calorie
0:47
balance on the other hand if you eat
0:49
only 1,500 calories and you keep burning
0:52
2,000 calories a day that means you're
0:54
in a 500 calorie deficit and will start
0:57
losing weight while you can technically
0:59
in increase how many calories you burn
1:01
with exercise this isn't effective long
1:03
term as your body adjusts to the extra
1:05
exercise by reducing how much it burns
1:08
in other ways why that happens is a
1:10
topic for another video that means that
1:12
the most effective way to get into a
1:13
calorie deficit is to control the amount
1:15
of food and therefore calories that you
1:17
eat and there are many different ways to
1:20
do that so even if the diets seem very
1:23
different the principle is always the
1:24
same keto diets work because fewer
1:27
carbohydrates mean fewer calories
1:30
vegan diets work because fewer animal
1:32
products mean fewer calories lowfat
1:35
diets work because lowfat means fewer
1:38
calories the principle is exactly the
1:41
same restrict a food or food group to
1:43
reduce calories and lose weight but
1:46
you're better than some restrictive diet
1:48
because you're watching this video and
1:49
now you know the principle of fat loss
1:51
and don't have to try some stupid diet
1:53
just to lose weight you're welcome in
1:54
advance so how do you actually figure
1:56
out how much to eat in order to lose
1:58
body fat I'm going to talk about two
2:00
methods today firstly you can calculate
2:02
your maintenance calories that's how
2:04
many calories you need to maintain your
2:06
body weight you do this by knowing your
2:08
basal metabolic rate and multiplying it
2:11
by an activity factor for your basal
2:13
metabolic rate or BMR there are a lot of
2:15
formulas available and one that I really
2:17
like to use is the Harris Benedict
2:19
equation which looks a little like
2:21
this just enter in your details for
2:24
weight age and height and it'll give you
2:26
your BMR once you have that you need to
2:29
m multiply it by an activity Factor this
2:32
accounts for the added energy that you
2:34
burn by being active typically for
2:36
someone who doesn't walk much and has a
2:38
desk job an activity factor of 1.1 or
2:40
1.2 is okay if someone is moderately
2:43
active with exercise a few days a week
2:44
and walks a little bit more an activity
2:46
factor of 1.3 to 1.6 might be okay or
2:49
for someone with an active job like
2:50
manual labor and a lot of exercise daily
2:52
an activity factor of 1.7 to even 2 plus
2:56
could be useful activity factors are
2:58
notoriously inaccurate so don't don't
3:00
worry about picking the right one you'll
3:01
need to adjust later anyway so once you
3:04
pick an activity multiplier multiply it
3:06
by your BMR and that will give you a
3:08
rough idea of your total daily energy
3:11
expenditure or TDE alternatively you can
3:14
search for a calorie calculator online
3:16
put your details in there and it'll
3:18
calculate your calories for you you can
3:19
check out the my protein calorie
3:20
calculator by clicking on the link in
3:21
the description below now you may think
3:24
that I haven't given a very detailed
3:26
description of how to calculate calories
3:28
and the reason is after working with
3:30
hundreds of clients with different body
3:32
composition goals I know for a fact that
3:35
calculating their energy expenditure
3:37
with a formula just isn't that important
3:40
here's the thing you probably don't even
3:42
need to use a calorie calculator because
3:44
they're just estimations of what you
3:46
should eat the best way to calculate
3:48
your calories is to actually monitor
3:51
your body weight and track your calories
3:53
and just reduce your calories a little
3:55
until your weight starts to go down that
3:57
weight is far better than any online
3:59
calculator and helps you adjust your
4:01
calories over time once you know how
4:03
many calories you burn to maintain
4:04
weight if you want to lose weight you
4:06
need to eat fewer calories in that now
4:09
the only way you can eat less is by
4:11
knowing how much you're eating at the
4:13
moment now again you can do that in two
4:14
ways you can use a calorie or macr
4:16
tracker literally any of them is fine
4:19
and use that to eat for your calories or
4:22
you can just keep a rough food diary of
4:23
what you eat daily and just reduce your
4:25
portion sizes the advantage of the
4:26
calorie tracker is it gives you details
4:28
on macronutrients like protein carbon
4:29
and fats which we'll talk about in a
4:31
moment you'll also need to measure your
4:33
progress and the easiest way to do that
4:35
is by weighing yourself daily without
4:37
monitoring your progress you have no
4:39
idea if what you're doing with your diet
4:41
is working there are plenty of other
4:43
ways to measure your progress taking
4:45
measurements around your hips and waist
4:46
or taking progress photos but the scale
4:49
is probably the easiest I'm not saying
4:51
it's the best but it's the easiest I say
4:53
measure it daily because your scale
4:55
weight can change a lot from dayto day
4:57
so if you measure it daily and then get
4:59
a weekly average that's probably a much
5:01
better measure of your progress one
5:03
thing to bear in mind when you're in a
5:04
calorie deficit is that your weight loss
5:06
will eventually slow down and stop even
5:10
if you're still eating what was a
5:11
calorie deficit for you before this is
5:15
totally normal and happens because when
5:16
you lose weight well lighter bodies need
5:19
less energy and there's also some
5:21
metabolic adaptation to dieting this
5:23
just means that your metabolism slows
5:24
down a little to compensate for to
5:26
reduce calories the only thing you can
5:27
do at this point is drop calories first
5:29
further to get back into a deficit again
5:32
it sucks but that's just the way
5:34
metabolism works now I haven't said how
5:36
much you should drop your calories by
5:38
because that depends on how fast you
5:40
want to lose weight if you have a bigger
5:41
calorie deficit you lose weight faster
5:43
and while some people like that because
5:45
it can help keep them motivated
5:47
personally I think a slower rate of
5:48
weight loss is a little bit better it's
5:50
easier to manage because you're not
5:52
dropping your calories crazy low for
5:54
some people a hard deficit or a big
5:56
deficit is easy to get sick of leading
5:59
to give up and end up robbing a bakery
6:02
slower weight loss will help you
6:04
maintain more muscle mass too so
6:06
depending on how fast you want to lose
6:08
weight you could consider a deficit of
6:10
200 to 500 calories that means 200 to
6:13
500 calories below your total daily
6:16
energy expenditure now the principle of
6:19
weight loss is very simple but putting
6:21
it all into practice is not easy at all
6:24
especially when we haven't even spoken
6:26
about other factors like protein fats
6:27
and carbs or motivation for dieting
6:29
habit change and just why losing weight
6:31
is so hard these are all really
6:33
important topics and I've spoken about
6:35
them before in previous videos so please
6:37
check those out so what do you think do
6:40
you think you know how to work out a
6:41
calorie deficit as always if you have
6:43
any questions let me know in the
6:44
comments below and remember to like And
6:46
subscribe to the my protein YouTube
6:47
channel for more great evidence-based
6:49
nutrition information
6:54
[Music]
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