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Calories explained! Why you're not losing weight | Nutritionist Explains | Myprotein
Aug 3, 2026
Calories explained. Why you're not losing weight. Learn how calories, energy balance, and fat loss actually work, plus the most common reasons people struggle to lose weight despite eating what they believe is a calorie deficit.
In this video, expert nutritionist Dr Richie Kirwan explains the science of calories, calorie deficits, and weight loss, helping you understand why the scales may not be moving and what you can do to achieve sustainable fat loss.
Key Facts:
Weight loss is driven by maintaining a calorie deficit over time.
Hidden calories, portion sizes, and liquid calories are common reasons people unintentionally eat more than they realise.
Exercise helps increase energy expenditure, but nutrition has the biggest impact on creating a calorie deficit.
Daily body weight naturally fluctuates due to water, glycogen, sodium intake, and digestion.
Consistency over weeks is far more important than day-to-day changes on the scales.
FAQ:
Q: Why am I not losing weight in a calorie deficit?
A: The most common reasons include underestimating calorie intake, overestimating calories burned, inconsistent tracking, or not maintaining a true calorie deficit over time.
Q: Do calories really matter for weight loss?
A: Yes. Regardless of the diet you follow, maintaining a calorie deficit is the fundamental driver of fat loss.
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0:00
You've been eating well all week. You've
0:01
been going to the gym, you've cut out
0:03
all the junk, but then you step on the
0:05
scale on Friday morning expecting
0:07
results and nothing. Maybe it even went
0:10
up. So, what the hell is going on?
0:16
How's it going, guys? My name's Richie
0:18
Carwin. I'm a registered nutritionist,
0:20
researcher, and university lecturer in
0:22
nutrition and exercise physiology.
0:24
Today, we're going to talk about one of
0:26
the most common and genuinely
0:29
frustrating experiences in dieting.
0:31
[music] Doing everything you think
0:32
you're supposed to do and still not
0:35
losing weight. And rather than just
0:37
telling you to try harder or eat less
0:39
and move more, I'm going to walk you
0:40
through the most common research-backed
0:43
reasons why people consistently eat more
0:46
calories than they think [music] they
0:48
do. Because in almost every case, that's
0:52
what's actually happening. [music] Now,
0:53
I want to be clear from the start. This
0:55
video is not about blaming you or making
0:58
you feel bad about your diet. It's about
1:00
identifying the blind spots that most
1:03
people have that nobody really talks
1:05
about and fixing it. Because once you
1:07
can see where the calories are actually
1:09
coming from, the whole thing gets a lot
1:12
easier. So, let's get into it. Before we
1:14
get into the specific reasons, [music] I
1:16
want to establish one central idea that
1:18
runs through this whole video. Weight
1:20
loss requires a calorie [music] deficit.
1:23
That's not an opinion, that's just how
1:25
energy balance works. Every diet that
1:28
has ever successfully helped someone
1:30
lose weight, whether that's keto, vegan,
1:32
low-fat, [music] carnivore, whatever,
1:35
has worked because it helps that person
1:38
eat fewer calories than they burn.
1:39
[music] Different diets are just
1:41
different methods of helping people get
1:43
into a calorie deficit. Now, here's the
1:45
thing.
1:46
The people I'm talking to today are not
1:48
failing to lose weight because the laws
1:50
of physics have somehow magically
1:53
stopped working. They're not getting the
1:54
results they want because somewhere
1:57
between what they think they're eating
1:59
and what they're actually eating there's
2:01
a gap and that gap is big enough to
2:04
cancel out their deficit completely. So,
2:07
what I'm going to do now is walk you
2:09
through the most common ways that gap
2:11
appears because they are far more
2:14
predictable than you think and a lot of
2:16
them aren't that obvious which is
2:18
exactly why they keep catching people
2:21
out. First one, I don't track, I just
2:23
eat clean. The first reason and honestly
2:26
one of the most common is not tracking
2:29
calories at all. Now I get it, calorie
2:31
counting has a bad reputation. People
2:33
find it tedious, obsessive or just not
2:36
sustainable long term and those are all
2:39
fair criticisms and there are genuinely
2:41
a lot of people who should avoid
2:43
tracking calories entirely because it
2:45
can become a real obsession. But here's
2:47
the problem.
2:48
When people ditch the tracking, they
2:50
often replace it with a simpler rule.
2:53
They just decide that certain foods are
2:54
good or safer, God forbid, clean and
2:57
just eat those foods freely without any
3:00
real limit. You see this everywhere.
3:02
>> [music]
3:03
>> Someone goes keto and figures fat is
3:05
basically unlimited now. Someone goes
3:06
plant-based and decides fruit and nuts
3:08
are fair game in any quantity. Someone's
3:10
eating clean and loading up on olive
3:13
oil, avocado, granola and peanut butter
3:15
because those are all healthy foods and
3:17
they are healthy foods. Nobody is
3:19
disputing that but healthy and low
3:21
calorie are not the same thing and that
3:23
distinction matters enormously when
3:25
you're trying [music] to lose weight.
3:27
Let's put some numbers on this because I
3:28
think it really helps. A heaped
3:31
tablespoon of peanut butter which is a
3:33
completely normal amount to put on a
3:35
couple of slices of bread is around 190
3:37
calories. A medium avocado is about 240
3:41
calories. A small handful of mixed nuts,
3:44
maybe 40 grams, [music] is around 250
3:47
calories. A tablespoon of olive oil is
3:49
around 120 calories. None of these are
3:52
bad foods, but all of them are foods
3:55
that people often eat without really
3:58
thinking about the calorie content
4:00
because [music] they've mentally filed
4:01
them under healthy. And this isn't just
4:04
anecdotal. Research has shown that
4:07
people following self-selected diets,
4:09
including those they consider to be
4:11
healthy, consistently and significantly
4:15
underestimate [music]
4:16
how much they actually eat. One
4:19
particularly well-known study by
4:20
Lichtman et al. [music] found that a
4:22
group of people who reported being
4:24
resistant to weight loss were eating
4:26
nearly twice as many calories as they
4:28
believed, despite being convinced they
4:31
were in a deficit. They weren't lying.
4:33
They just genuinely didn't know. Now,
4:35
the point isn't that you need to
4:37
obsessively weigh every single thing you
4:39
eat for the rest of your life. It's that
4:41
if you're not losing weight and you're
4:43
not tracking anything, then you
4:45
genuinely don't know how many calories
4:47
you're eating. Full stop. And assuming
4:49
you're in a deficit because your food
4:51
choices feel healthy is not the same as
4:54
actually being in one. Next up, you do
4:56
track, but probably [music] not as
4:58
accurately as you think. Okay, so maybe
5:00
you are tracking your calories. That
5:02
puts you ahead of most people. But
5:04
here's the problem. Tracking calories
5:06
and tracking calories accurately [music]
5:08
are two very different things, and the
5:10
gap between them is where a lot of
5:12
people's deficits start to disappear.
5:14
The most common mistake is estimating
5:16
portion sizes rather than weighing.
5:18
[music] And I understand why nobody
5:20
wants to pull out a food scale every
5:21
time they make dinner. But research
5:23
consistently shows that people are
5:25
genuinely
5:27
terrible at estimating how much they're
5:29
eating. We tend to underestimate
5:31
portions of calorie-dense foods [music]
5:33
and overestimate portions of healthier
5:35
foods like vegetables, which means that
5:37
errors almost always go in the wrong
5:40
direction. To give you an example, if
5:41
you pour what you think is a 40-g
5:44
serving of oats and actually weigh it,
5:46
most people are probably closer to 60 or
5:49
70 g. [music] Seriously, I eat oats
5:51
almost every day and I still can't
5:54
portion it out without weighing it.
5:56
That's just what happens when you
5:58
eyeball something. Over multiple meals a
6:00
day, those small errors stack up into
6:03
meaningful services. Then there are the
6:06
foods that don't make it into the
6:07
tracker at all. Cooking oils are
6:09
probably the biggest offender here. A
6:11
couple of glugs of olive oil into a pan
6:12
looks pretty innocent, but can easily be
6:15
200 or 300 calories that never get
6:18
logged. Sauces, dressings, butter, the
6:21
handful of nuts grabbed from the kitchen
6:22
counter, the couple of bites you had
6:24
while cooking. None of these feel like
6:27
meals, so none of them tends to get
6:29
tracked. But they all have calories. And
6:31
this brings me to the really important
6:33
point of liquid calories, which deserve
6:36
[music] a special mention because they
6:38
are genuinely one of the easiest ways to
6:40
consume a large number of calories
6:42
>> [music]
6:42
>> without really registering that you've
6:46
eaten anything at all. Your body is
6:48
simply not very good at recognizing
6:50
calories consumed in liquid form, which
6:52
means they rarely reduce your appetite
6:54
the way solid food does. The obvious
6:56
ones are alcohol and sugary drinks.
6:59
Alcohol contains seven calories per
7:01
gram, which makes it the second most
7:02
calorie [music] dense macronutrient
7:04
after fat. And a pint of lager is around
7:06
200 calories, as [music] is a large
7:08
glass of wine. Two or three of those on
7:10
an evening, which many people wouldn't
7:12
even consider a big night out, can add
7:14
up to 600 calories to [music] a day that
7:16
was otherwise reasonably well
7:18
controlled. But it's not just alcohol. A
7:20
large latte from a coffee shop can be
7:21
200 to 250 calories. A glass of orange
7:24
juice with breakfast is around 100 to
7:25
120 calories. These things feel [music]
7:27
like normal parts of a healthy routine,
7:29
so they rarely get a second thought and
7:32
they rarely get tracked. So, here are a
7:34
few practical improvements that can
7:36
genuinely help. Weigh the foods you eat
7:38
regularly for even in a couple of weeks
7:41
so you actually know what your portions
7:43
should look like. Log everything,
7:45
including oils and sauces, even if it's
7:47
an estimate, [music] and get into the
7:49
habit of counting your drinks, alcoholic
7:51
or otherwise,
7:53
as part of your daily total. I also want
7:54
to point out that I don't think people
7:56
should bother tracking their non-starchy
7:59
vegetables. Think
8:00
>> [music]
8:00
>> green leafy veg, like broccoli, or salad
8:02
veg, like peppers, tomatoes, and
8:03
cucumbers. They're really low in
8:05
calories, and most people don't get
8:06
enough of them as is. So, I don't want
8:09
anybody limiting them for fear of
8:11
calories. None of this should become a
8:13
permanent obsession. But, if you're
8:15
wondering why the scale isn't moving,
8:17
this is one of the first places to look.
8:20
Next up, the problem with cheat days.
8:22
Right. Let's talk about cheat days, and
8:25
I want to be clear that I'm not here to
8:27
tell anyone [music] they can never eat
8:29
what they want. That's not the point of
8:31
this video, and honestly, that's not a
8:33
particularly healthy approach to food or
8:35
life, either. The issue I want to talk
8:37
about is a very common problem, where
8:40
someone spends the whole week being
8:42
disciplined, [music] and then designates
8:44
one full day where anything goes.
8:48
And the problem with that is plain
8:49
[music]
8:50
old math. Let's say you do a really
8:53
solid job Monday through Friday. You eat
8:55
500 calories below your maintenance each
8:57
[music] day, which is a decent deficit.
9:00
That's a total deficit of 2,500 calories
9:02
across [music] the week.
9:04
Great progress. Then Saturday arrives,
9:06
and you feel you deserve a little cheat
9:07
day. A big breakfast, a takeaway lunch,
9:10
a meal out for dinner, some [music]
9:11
snacks, a few drinks. You're not
9:13
tracking because that's the point of a
9:15
cheat day. So, you're not really sure
9:17
how much you've eaten. But, if you've
9:19
eaten even 1,500 calories above your
9:22
maintenance on that day, you've already
9:25
wiped out more than half of the week's
9:27
entire deficit in one sitting. And 1,500
9:30
above maintenance on a full cheat day
9:32
is, honestly,
9:34
>> [music]
9:34
>> pretty damn easy to do. The frustrating
9:36
part is that this can happen without the
9:38
day feeling particularly excessive. A
9:40
big cooked breakfast alone can be 800 to
9:43
1,000 calories.
9:44
Add a takeaway, a couple of drinks, and
9:46
some snacking throughout the day, and
9:48
you can very easily hit 2,000 to 3,000
9:50
[music] calories above your maintenance
9:53
without it feeling like a binge.
9:55
>> [music]
9:55
>> At that point, the week's deficit is
9:57
either heavily eaten into, pun intended,
9:59
or gone entirely. And then you step on
10:02
the scale on Monday and wonder why
10:03
nothing is happening. Now, there is a
10:06
version of a planned higher calorie day
10:08
that can work well within a diet called
10:10
a refeed day, where calories are
10:12
deliberately increased, usually with
10:14
carbs, to support training performance
10:16
and to help manage some of the hunger
10:18
and boredom effects of prolonged [music]
10:20
dieting. But that's a controlled,
10:22
calculated increase, not an unlimited
10:25
free-for-all. The two things are very,
10:27
very different. If you enjoy having a
10:29
more relaxed day in the week, that's
10:31
absolutely fine, and it's probably
10:32
better for long-term adherence than
10:34
trying to be in a deficit every single
10:36
day. But the keyword is relaxed, not
10:39
unlimited. Even a rough awareness of how
10:41
much you're eating on that day can make
10:43
[music] the difference between a week of
10:45
genuine progress and a week of spinning
10:47
your wheels. Next up, the weekend
10:50
problem. Now, the previous section was
10:52
about people who deliberately have a
10:53
cheat day, but this section is about
10:55
something slightly different and in some
10:57
ways a little more [music] troublesome
10:59
because it's not intentional at all.
11:02
It's just what happens to most people's
11:04
eating habits at [music] the weekend.
11:06
Think about how a typical week actually
11:07
looks.
11:08
Monday through Thursday, you're in a
11:10
routine. You're making food at home, you
11:12
know roughly what you're eating, you're
11:13
probably being reasonably careful. Then
11:15
Friday evening arrives.
11:17
You might grab a takeaway [music] or go
11:19
out for dinner.
11:20
Saturday, you sleep in, you have a
11:21
bigger breakfast, maybe brunch.
11:24
You could be doing something social in
11:25
the evening. Sunday might involve a
11:27
roast or leftovers or snacks in front of
11:29
the TV. And across those two or three
11:31
days, you've probably had a few drinks
11:34
at some points as well. None of this
11:35
feels like [music] a binge. It just
11:37
feels like a normal social weekend. What
11:40
research has shown that people's calorie
11:42
intake on weekends is consistently and
11:45
significantly higher than on weekdays.
11:46
[music]
11:47
And that leads to weight gain over time.
11:49
And the tricky thing here is that unlike
11:51
an actual cheat day, most people don't
11:53
even register that the weekend is
11:54
different. They don't think of Friday
11:56
night's takeaway and Saturday's drinks
11:57
as a diet decision because they don't
11:59
feel like diet decisions. [music] They
12:01
just feel like life, which is exactly
12:03
why this pattern is so easy to fall into
12:05
and so hard to spot without actually
12:07
tracking it by using it. Now, again, I
12:09
want to be clear that I'm not suggesting
12:11
anyone needs to eat like a monk every
12:13
day of their life to lose weight.
12:15
The point is just to be aware of the
12:16
[music] pattern. If you're in a deficit
12:18
Monday through Friday, but consistently
12:20
eating well above maintenance from
12:22
Friday evening through Sunday, you may
12:24
be sabotaging yourself [music] without
12:26
even realizing it. A simple approach
12:27
that genuinely helps is to at least keep
12:30
a rough count [music] at the weekend,
12:32
even if you're not being strict. You
12:33
don't need to weigh your Sunday roast,
12:35
but having a general sense of whether
12:37
your weekend is a slight increase or a
12:40
total free-for-all can make a big
12:42
difference to your progress over time.
12:45
Next up, your calorie target was
12:46
probably wrong from the start. Okay, so
12:49
far we've talked about people who either
12:51
aren't tracking at all or who are
12:53
tracking but losing calories in the
12:54
gaps. But this section is about a
12:56
different problem entirely, one that
12:58
happens before you've even [music] eaten
13:00
a single meal on your diet. And it comes
13:02
down to how a lot of people set their
13:05
calorie targets in the first place. Lots
13:07
of people start a diet by going online
13:09
and using a calorie calculator. You
13:11
enter your height, weight, [music] age,
13:13
gender, and it spits out a number for
13:15
how many calories you burn per day.
13:17
Sounds straightforward, right? But
13:19
there's one step in that process where
13:21
things tend to go badly wrong.
13:23
>> [music]
13:23
>> And that's when the calculator asks you
13:24
to select your activity level. The
13:26
options are usually something like
13:28
sedentary, [music]
13:29
lightly active, moderately active, very
13:32
active, and so on. Problem is that most
13:33
people think about the fact that they go
13:35
to the gym three or four times a week
13:37
and select moderately active or higher.
13:39
And when they do that, they can
13:41
overestimate their calorie needs by a
13:42
few hundred calories per day. So, those
13:45
activity categories are supposed to
13:47
reflect your total daily movement, not
13:49
just [music] your workouts. And when you
13:51
actually look at how most people spend
13:53
the rest of their day,
13:55
>> [music]
13:55
>> it's a lot of sitting. Sitting at a
13:56
desk, sitting in the car, sitting on the
13:58
sofa.
13:59
Research that actually measures activity
14:01
with things like accelerometers
14:02
consistently shows that people
14:04
significantly
14:06
overestimate how physically active they
14:08
actually are across the full day. If you
14:10
exercise for an hour, but spend most of
14:12
the other 15 waking hours mostly sitting
14:14
on your bum, you're probably closer to
14:16
lightly active than moderately [music]
14:18
active, even if the gym sessions are
14:20
really intense. The difference between
14:22
those two categories in [music] a
14:23
typical calculator can easily be 300 to
14:25
400 calories a day. So, if your
14:27
calculated deficit is 500 calories and
14:30
your maintenance is already
14:32
overestimated by 300, you're not in a
14:34
500 calorie deficit. You're in a 200
14:36
calorie deficit at best. And that's
14:38
assuming everything else is accurate,
14:40
which, based on everything else I've
14:42
said today,
14:43
probably isn't. The practical fix here
14:45
is actually pretty simple, and it's
14:47
something I'd recommend regardless of
14:48
what calculator [music] you use. Don't
14:50
rely on the number a calculator gives
14:52
you as gospel. Use it as a rough [music]
14:55
starting point, then let your body
14:56
weight tell you whether it's right. If
14:59
you've been eating at your calculated
15:00
deficit for three or four weeks and your
15:02
weight hasn't moved, your maintenance is
15:05
likely lower than you think, which means
15:07
you need [music] to eat a little less.
15:09
The scale is a far more honest feedback
15:13
tool than
15:13
>> [music]
15:13
>> any online calculator. Next up,
15:16
overestimating calorie burn from
15:18
exercise. Right, last one. And this is
15:21
probably the most relatable one in this
15:23
video because I think almost everyone
15:25
who has ever been to the gym is guilty
15:27
of this. You finish a tough session,
15:29
you're sweating, you feel like you've
15:30
worked hard, and the treadmill or your
15:32
smartwatch tells you that you've burned
15:34
600 calories. So, you figure that you've
15:36
earned yourself something extra at
15:37
dinner.
15:38
Maybe a bigger portion, maybe a treat,
15:40
maybe a couple [music] of drinks
15:41
because, hey, you've done the work. And
15:44
that all seems logical right up until
15:46
you realize that the machine's calorie
15:49
estimate is probably wildly inaccurate.
15:52
Studies comparing cardio machine calorie
15:54
estimates to actual measured energy
15:57
expenditure [music]
15:58
have found that machines can
15:59
overestimate calorie burn by anywhere
16:02
from 20 to 100%
16:05
depending on the machine and the
16:06
individual. Elliptical trainers in
16:08
particular tend to be among the worst
16:10
offenders. And wearable fitness
16:12
trackers, while generally better than
16:14
machines, still show big errors in
16:16
calorie estimation at the individual
16:18
level. But, even if the number [music]
16:20
were accurate, there's a second problem
16:23
that a lot of people don't consider. And
16:25
that's compensation. Research has
16:27
consistently shown that exercise tends
16:30
to increase appetite in some people,
16:32
meaning they often eat more in the hours
16:35
following a workout, sometimes without
16:37
even noticing. On top of that, research
16:40
suggests that when people increase their
16:42
exercise, they unconsciously reduce
16:45
their general movement throughout the
16:47
rest of the day, sitting more, moving
16:50
less, which partially offset the extra
16:53
calories burned from exercise. None of
16:54
this means exercise is useless for
16:56
weight loss. It has [music] a huge range
16:58
of health benefits. It helps preserve
17:00
muscle during a diet, and it absolutely
17:03
contributes to a calorie deficit [music]
17:04
when everything else is managed well.
17:06
But, on its own, without the diet side,
17:09
exercise is a pretty unreliable weight
17:12
loss tool. And using a machine's calorie
17:15
readout as justification to eat [music]
17:18
more is one of the most common ways
17:21
people quietly undo [music] their
17:23
deficit without realizing. The simplest
17:25
fix is to not eat back your exercise
17:28
calories based on what a machine tells
17:30
you. Keep your food intake consistent.
17:33
Let the exercise add to your deficit
17:35
quietly in the background and let your
17:37
weekly scale average [music] tell you
17:39
whether it's working or not. Next up,
17:41
eating out, the calorie blind spot. This
17:43
next section is a short one but worth
17:45
mentioning because it's a very easy trap
17:47
to fall into, especially if you're
17:49
otherwise being fairly careful with your
17:51
diet. When you cook at home, you've got
17:52
a reasonable idea of what's going into
17:54
your food. When you eat out, you don't.
17:57
And the difference can be significant.
17:59
Restaurant portions are generally bigger
18:01
than home cooked equivalents and meals
18:03
are [music] often prepared with a lot
18:05
more oil, butter, and sauce than you'd
18:07
use yourself because those things make
18:09
food taste good and restaurants are in
18:12
the business of making food taste good.
18:14
A dish that looks like a reasonable
18:15
dinner might have had three or four
18:17
tablespoons of oil or butter added
18:19
during cooking that you'd never know
18:21
about, adding way more calories than you
18:23
might [music] expect. That doesn't mean
18:25
you can't eat out. It just means that if
18:27
you're eating out multiple times a week
18:29
and wondering why your diet isn't
18:31
working, those meals are potentially a
18:34
likely contributor. A lot of restaurants
18:36
now display calorie information, which
18:38
makes this a lot easier to manage, but
18:40
even then, those calorie values may not
18:43
be all that accurate. Just being aware
18:45
that restaurant meals are likely higher
18:47
in calories than they look is useful in
18:49
itself. So, there you have it. A list of
18:52
reasons why people who think they're in
18:53
a calorie deficit often aren't. And the
18:56
common thread running through all of
18:58
them is the same thing. I said at the
19:00
very start, it's not that the laws of
19:02
physics stop working, it's that the gap
19:04
between what people think they're eating
19:06
and what they're actually eating is a
19:08
lot bigger than they realize. [music]
19:10
The good news is that once you can see
19:12
where that gap is coming from, it
19:13
becomes a lot easier to close it. If any
19:16
of these reasons resonated with you, or
19:18
if you've spotted yourself in one of
19:19
these sections, let me know in the
19:21
comments below. And if you found the
19:22
video useful, make sure to give it a
19:24
like and subscribe to the Myprotein
19:26
YouTube channel for more great
19:27
evidence-based [music]
19:28
nutrition information.
#Sports