Fans of intermittent
fasting (IF) absolutely rave about all the purported benefits, yes. But behind
all the talk about what type of fasting schedule is right for you or
whether you can combine
IF with other diets like keto, there’s an often-overlooked
fact: IF can still cause side effects or have its negatives…especially if
you’re not doing it right.
“It’s important to figure out which style of IF works for you,
whether that’s a shorter versus longer fasting window or only doing it so many
days per week,” says Alyssa Koens, lead registered dietitian of weight loss
coaching company Profile Sanford.
“If you’re consuming too few calories or nutrients during fasting times, you
could have side effects.”
But since there aren’t any formal guidelines for how many calories
you should be consuming during IF – or for what kinds of foods you should be
filling up on during non-fasting hours – it can be hard to hit your IF groove
without some bumps in the road first…assuming it’s even the right choice for
you at all. And there are some signs to watch out for that might mean it’s just
not the best fit for you and your lifestyle.
first: If you’re wondering why IF is so popular in the first place, there may
be potential benefits of intermittent fasting.
There are several potential positive effects of IF,
including weight loss, better appetite control, and lower insulin levels. The
main issue is that none of those benefits have been heavily researched in any
way. The research is also the scantest in humans (compared to, say, the
research in mice).
It’s also unclear if the root cause of the purported benefits is
intermittent fasting itself (e.g. how it affects your body, say, on a cellular
level) or simply the calorie restriction. So it’s kind of trial and error at
this point to see whether an IF eating style works for you and your body.
Read more: What you need to know before you try a fasting diet to lose weight
On the other hand, there are a bunch of possible negative side
effects with IF.
As mentioned, the
upsides of intermittent fasting are still very much in the research phase – but
there are some promising findings there. However, there’s also plenty of
anecdotal evidence that IF does come with some possible negative side effects,
and you shouldn’t start an IF eating plan without hashing those things out with
your doctor first.
Here are 10 red flags to watch out for. And if you notice any of
these side effects, that means stop IF and talk to your doctor or a nutritionist
1. Feeling hangry
We’re not 100% certain that “hangriness” is a real word,
but it’s definitely a real sensation. This is the feeling of grouchiness,
grumpiness, or overall irritability that comes with not being able to eat when
your body is telling you it’s hungry.
As WH previously reported, teaching your body to go 16 hours
without food takes some practice, and some people’s bodies
might not ever be happy eating within a restricted window.
In theory, if you’re consuming enough protein later in the day or
night, you shouldn’t be starving first thing in the morning. But if you are,
that’s a sign you need to make some dietary adjustments during your caloric
intake period to avoid turning into a major crank – or it’s a sign that you’re
just not vibing well with fasting. For some people (e.g. those who work out a
ton), not eating for long periods may just not be ideal for them at all – and
that’s definitely something worth considering. Don’t force it.
2. Fatigue or brain
Ever found yourself yawning over and over mid-morning, only to
realise you never got around to eating breakfast? Since not eating breakfast is
typically how most people do IF, realising that you’re excessively tired every
day – or making dumb mistakes because you’re wading through brain fog – is a
tip-off that you’re not eating the right foods during non-fasting hours or that
fasting isn’t fitting in with your lifestyle needs.
“Pay attention to what you’re fuelling your body with,” says Koens.
“You can eat what you want on IF, but you should still be fuelling it with good
food that will make you feel healthy and strong.” And if you just feel way
better eating breakfast most days, listen to your body.
3. Food obsessions
Being on any kind of restrictive diet can affect your relationship
with food, says Koens. While some people like the rigidity of IF, others may
find themselves focusing way too much on when they can eat and how many
calories they’re getting.
Spending an excessive amount of time thinking about the quality or
quantity of your food every day can lead to a type of eating disorder called
orthorexia. According to The National Eating Disorders Association,
having orthorexia means you focus so much on “correct” or “healthful” eating
that it actually has a detrimental effect on your overall well-being.
That shouldn’t be the goal of any diet, says Koens: “You want to
focus on forming a healthy, positive relationship with food.”
Read more: Would it be a terrible idea to try intermittent fasting while breastfeeding?
4. Low blood sugar
If you’re having persistent nausea, headaches, or dizziness during
IF, that’s a red flag that indicates the diet may be throwing your blood sugar
out of whack. As WH previously reported, diabetics
should avoid any kind of fasting diet for this exact reason: IF
can cause you to become hypoglycaemic, a dangerous condition for anyone with
insulin or thyroid problems.
5. Hair loss
Seriously? Yup. Koens says that sudden weight loss or a lack of
proper nutrients, especially protein and B vitamins, can cause hair loss.
An important point: While IF doesn’t necessarily lead to a loss of
nutrients, it tends to be harder to eat a well-rounded diet when you’re
cramming a whole day’s worth of eating into a handful of hours. If you think
more hair than usual is falling out in the shower every day, re-evaluate the
nutrition content of your daily meals and speak with your doctor about whether
IF is really a wise move for you.
6. Changes in your
Here’s another side effect of sudden weight loss (which can be a
result of IF): Women who lose a dramatic amount of weight or are consistently
not getting enough calories every day might find their menstrual cycles slow
down or even stop completely.
Per the Mayo Clinic, women who have excessively low body weight
are prone to a condition called amenorrhea,
or the absence of menstruation. Sudden weight loss or being underweight can
disrupt your typical hormone cycle and cause missed periods; so while you might
be rejoicing in the way IF has helped you shed pounds, you could also be
depriving your body of calories it needs to function.
If you stop getting your period and think it’s linked to
intermittent fasting habits you’re practising, stop fasting and speak with your
gynaecologist to troubleshoot.
All backed up? IF could be to blame. “Any diet can cause an upset
stomach if you’re not getting enough fluid, vitamins, protein, or fibre,” says
Koens, who emphasises the importance of staying hydrated all
It’s easy, she explains, for people to forget to drink water
during fasting hours – but going 16 hours a day without enough fluid is a
recipe for (gastrointestinal) disaster. So if you’ve started an IF diet and
can’t seem to get your bowel movements to happen regularly (or at all), it’s
time to hit pause on your plan and speak with a nutritionist or MD about what’s
happening (er, or not happening in this case!).
Read more: Can you drink black coffee while fasting or not?
8. Unhealthy diet
Even if IF doesn’t trigger a serious disorder like orthorexia, it
could still bring about some pretty unhealthy eating habits. In addition to not
getting the proper nutrients, you could also find yourself making bad
nutritious choices during non-fasting hours.
“The main worry is setting off binge-eating behaviour, because you
are so hungry you’re eating 5 000 calories [and going way over your daily
Charlie Seltzer, weight-loss physician and certified personal
trainer, previously told WH.
If this sounds like you, you may be better off working with an RD
to find a plan that doesn’t force you to restrict your eating hours and instead
focuses on fuelling your body with proper nutrients around the clock, not in a
9. Sleep disturbances
Koens says that many people report improved sleep patterns while
doing IF, possibly due to the way IF helps curb late-night snacking habits, and
in turn, an inability to fall asleep because your stomach is busy still
digesting that 10 p.m. nosh.
However, there is some research pointing to the opposite effect. A 2018
review in the journal Nature and Science of Sleep points
to evidence that diurnal intermittent fasting (meaning daytime fasting) causes
a decrease in
rapid-eye movement (REM) sleep. Getting enough REM sleep has been linked to all
kinds of health
benefits, including better memory, cognitive processing, and
concentration, per the Harvard Business Review. It’s unclear why exactly.
If you notice you can’t fall asleep or stay asleep after you’ve
started an IF eating plan, again, hit pause and talk to a pro to make sure
you’re not hurting your health.
10. Mood changes
It would be weird if you didn’t experience any moodiness or hangriness during
IF, at least in the beginning. And while some people feel a serious boost of
energy or motivation once they adjust to fasting, it’s important to remember
that it is still
a restrictive diet. Feeling obliged to follow it could have negative effects
on your mood, especially if you’re becoming isolated from friends or family
members due to your diet restrictions.
If you’re feeling down, anxious, or discouraged about IF, it’s
crucial to stop and get in touch with a registered dietitian, psychologist, or
nutrition coach right away. They may be able to help you create a fasting
schedule that better suits your mind and body.
This article was originally
published on https://www.womenshealthsa.co.za/
Image credit: iStock