Which Diets Actually Work?
Debunking some common diets, and seeing which work! More Food and Health Science videos!
There are…a lot of popular diets out there.
So we thought we’d create a simple video
investigating which ones are scientifically
sound, and actually work.
From the outside it seems like a simple equation:
your weight is determined by the balance between
the calories you take in, and the calories
you burn. By changing what you eat or your
activity level, you can tip this equation
towards weight gain or loss. Which brings
us to our first category of diets:
Calorie Restriction. Companies like Weight
Watchers claim you can eat whatever you want,
as long as you stay below a prescribed number
of daily calories. Getting all your calories
from junk food is technically allowed, but
from a health perspective, it’s important
to think of the nutritional value of the foods
too. If you don’t, you risk heart problems,
nutrient deficiencies and chronic health issues.
Calorie Restriction with Optimal Nutrition
or CRON diets, generally reduce their caloric
intake by 20% while still meeting the daily
nutritional requirements. For example, instead
of having a whole apple, a CRON dieter will
just have the apple skin, which contains most
of the nutrients.
If used properly (and not excessively), calorie
restriction can be a safe and effective tool
for weight loss.
Next up is Carb Restriction. Many diets like
the South Beach, Atkins, or Zone Diet suggest
that carbs are the enemy of the fit body you’ve
always dreamed of.
The ideology claims that when more carbs are
taken in than burned off, the liver converts
them into fats. But for most healthy, reasonably
active people, carbs are broken down to glucose
and transported to the cells for energy. Very
little is actually turned into fat.
In response to excessive glucose, the body
uses insulin to turn it into glycogen, which
is stored in the liver and muscles. This glycogen
may later be broken down in times of low glucose,
to refuel the body.
But the type of carbs you eat do matter – those
from simple sugars like honey, fruit or sugar
are more readily turned into triglycerides
or fat than complex carbs like whole grains
and veggies. If you consistently eat way more
than necessary, and most calories are simple
carbs, then these will be converted to fat.
Low carb diets often have extreme restriction
at first; no starches like bread or pasta,
and no sugars including from fruits or even
alcohol. This can lead to some intense side
effects, including constipation, dry mouth,
bad breath, fatigue, dizziness and nausea.
In studies, carb restriction dieters tend
to lose weight faster, initially, compared
to those simply using calorie restriction,
but this is likely due to water loss, which
returns in later phases when you’re encouraged
to eat normally again.
On top of this, the Atkins diet, for example,
promotes caloric intake from high-fat and
high-protein sources, which means meats, cheeses,
cream, butter and…losing weight? Sounds
pretty good right? But many doctors show concern
over the high intake of saturated fat – that
may lead to more ‘bad’ cholesterol and
therefore an increased risk of heart disease.
Some claim these kinds of diets are dangerous
and unhealthy, given that they promote the
limitation of foods like carrots, sweet potatoes,
or apples, that provide the body with important
micronutrients and vitamins. Instead, people
require supplements, which the body is not
able to absorb as effectively as vitamins,
minerals and micronutrients in whole foods.
Then there are High Protein Diets. The main
principle is that protein rich foods are not
as easily broken down by the body and take
more energy to digest than carb-rich food.
This means you won’t feel hungry again as
quickly, and you’re more likely to run a
caloric deficit than if you ate the same number
of calories from carbs.
The Paleo Diet, for example, suggests that
10,000 years ago agriculture was introduced,
and the human diet changed from hunter-gathers
eating primarily meat, wild fruits, veggies
and nuts, to diets containing more grains.
And as a result, some believe the human body
isn’t designed to digest these processed
foods like grains, dairy, and breads. Some
also believe that grains lead to inflammation
related health problems, but this is largely
untrue except in the case of people with celiac
But because of it’s straightforward guidelines,
many find it easy to follow, and it does promote
more nutrient absorption. However, as paleo
cuts out all grains and legumes, we lose an
important source of dietary fibre necessary
to keep our bowels running smoothly. Not to
mention the high protein leads to nitrogen
production meaning stinky farts! Add to that
constipation which allows your digested material
to sit longer in the large intestine and continuing
to decompose and…yup. Smelly farts.
Now there is another class of diets we might
call the “Just Stop Eating” Diets. Those
looking to ‘get slim quick’ might be tempted
to only eat cabbage soup for 7 days, or do
the ‘Master Cleanse Diet’ which only allows
salt water in the morning and a concoction
of water, maple syrup, lemon and cayenne pepper
through the day, and a laxative tea at night
– but these diets are exceptionally unhealthy.
Not only is most of your weight loss from
water weight, but there are many side effects
such as dizziness, fatigue, dehydration and
The Master Cleanse can ever lead to a white
tongue, which some claim is the toxins leaving
your body, but it’s actually due to swelling
and a yeast infection of the mouth. And after
going through all that, you’re likely to
gain any weight lost after stopping.
Then of course there are straight up crazy
diets. Like eating cotton balls dipped in
soup or juice so that you feel full, which
of course provides hardly any nutritional
content and can cause intestinal blockages
which require surgical intervention.
Or how about the sleeping beauty diet where
you just…sleep? You can’t eat if you’re
always asleep! The truth is most diets focusing
on quick, dramatic results also have a ‘yo-yo’
effect, where you lose initial weight but
slow down your metabolic rate, so your body
starts burning less calories. And when you
start eating again…there’s all the weight
back, and often more!
After following contestants from the show
‘The Biggest Loser’ for 6 years – some
of which who had lost hundreds of pounds in
7 months – scientists noticed something interesting.
Not only did most of the participants in the
study regain their weight, but their metabolic
rates changed. One man in particular now burns
800 fewer calories a day than would be expected
for a man his size! This is 6 years after
leaving the show, showing how extreme measures
to lose weight – while they may be successful
at the time – have long lasting impacts on
your metabolism, making it harder to keep
off weight in the future.
The hard truth is, that even using many of
the principled diets, about 97% of people
regain everything lost and sometimes more
within 3 years. If you want to lose weight,
finding a diet that works for you and keeps
you motivated, with small incremental changes
is important. Of course, a number on a scale
doesn’t measure how healthy a person is,
though many struggle with this perception.
If food and weight preoccupations are a problem
for you or someone you know, check out the
description of this video for links with more