04 - Energy Deficit: Is Eating Less Always Better for Weight Loss?
Hello, welcome to the "Scientific Weight Loss Course." I am Jessica.
theories of weight loss. Starting from this lecture, we'll discuss
specific weight loss methods, getting down to the real battlefield of
weight loss for some practical training.
The last lecture mentioned that lifestyle adjustment is the most
effective and safest weight loss method. In this module, we'll break
down in detail the three main components of healthy lifestyle: dietary
adjustment, scientific exercise, and psychological factor management.
Starting from this lecture, we'll use three lectures to thoroughly
explain the most important component - dietary adjustment.
Dietary Adjustment: Creating an Energy Deficit
Regardless of which of the "three-body goals" falls short, we need to
make dietary adjustments - no exceptions. But when it comes to dietary
adjustment, what comes to mind? Dieting? Eating less? Controlling your
mouth? Actually, dietary adjustment is far more than this.
You might see crude regulations in some weight loss books or articles
requiring all dieters to consume only 1200-1500 calories daily for
women and 1500-1800 calories for men. I must say such regulations are
indeed useful, but their drawbacks are also very obvious.
The biggest problem is that calculating how much energy you consume in
a day is extremely difficult - even clinical nutritionists would
scratch their heads. The same braised pork dish made by this restaurant
versus that takeout will have different energy content; your mom was in
a good mood today and added an extra spoon of sugar while cooking; your
wife bought chicken at the supermarket that was slightly fattier... all
these can cause calculation results to be "off by a hair, wrong by a
mile."
Secondly, this method is too one-size-fits-all and lacks humanity. If
you're not very overweight, you might not need to eat so little at all;
but if you're particularly overweight, suddenly eating so little would
make you too hungry to persist.
Therefore, in the past decade, authoritative weight loss guidelines
have gradually abandoned this fixed-energy approach in favor of
creating energy deficits - a more effective and healthier method. That
is, as long as you create an energy deficit in your diet, making daily
energy intake less than consumption, with more water going out than
coming in, a person's weight will gradually decrease.
How large an energy deficit can achieve weight loss? The medical
conclusion is 500-750 calories - below or above this range won't work.
An energy deficit exceeding 750 calories might lead to a series of
nutritional deficiencies. Moreover, because you're eating too little,
our body will activate protective compensatory reactions, actively
reducing consumption, and weight might experience retaliatory rebound.
What if the energy deficit is less than 500 calories? Since our
calculations of energy intake and consumption are rough, if we
accidentally overestimate, the deficit might disappear, making weight
loss impossible.
Therefore, an energy deficit of 500-750 calories is most
cost-effective. In other words, as long as we make our daily energy
intake 500-750 calories less than our current total daily consumption,
theoretically you can successfully lose weight.
There's also an auxiliary principle to help you control this deficit
range: the smaller your BMI, the closer your energy deficit can be to
500 calories; the larger your BMI or if your weight has recently
increased, the closer it should be to 750 calories. Of course, if
you're severely overweight with a BMI exceeding 35, the energy deficit
can indeed be larger, but this requires professional medical guidance.
How do you achieve this energy deficit? The simplest method is to eat
less - directly consume 500-750 fewer calories of food daily than you
currently do, and the energy deficit emerges. How much is 500 calories?
About the energy content of a 100-gram bag of chips.
Eating this way, you'll likely successfully lose weight after 6 months.
Your Body Doesn't Know How Much Energy You Need
At this point, the question naturally arises: Won't you be hungry if
you suddenly eat 500-600 fewer calories? Isn't hunger the body telling
us it lacks energy?
Here I want to tell you two truths:
The first truth is that hunger is just a bodily sensation, not
representing bodily need.
Under long-term unhealthy lifestyle habits, the body most likely
doesn't know how much energy it needs. On one hand, it becomes
accustomed to eating that much, always filling the stomach completely;
on the other hand, it also obeys gut microbiome commands. When gut
microbiome wants to eat, it sends signals to the brain: "Your body is
hungry, eat quickly." Do you understand? Hunger doesn't mean you lack
energy. So don't worry - just eat according to the energy deficit
mentioned earlier.
The second truth is that low total energy intake doesn't mean you
have to eat less or diet.
As long as you choose foods with low energy density, such as eating
more fruits and vegetables rich in fiber, weight loss meals can also be
very filling. In the next lecture, we'll specifically discuss how to
combine weight loss meals to achieve low calories while being
satisfying.
Step One: Read Labels
Now the question comes: I'm not a nutrition expert - how do I know that
the food I eat less daily equals exactly 500 calories?
Now I'll teach you the fundamental method to solve this problem.
Becoming an expert might require ten thousand steps, but the distance
between you and an expert for solving this problem is only three steps.
The first step is reading labels.
National regulations require all finished foods - packaged foods - to
have food labels. This label isn't complex; it's divided into two
parts. The upper part is the "ingredient list," arranged by proportion
from most to least, with main components listed first and lesser
amounts toward the end. Learning to read this will help you discover
some foods that don't live up to their names. For example, some "egg
butter cookies" have eggs listed as the eleventh ingredient, and butter
isn't even included.
But this isn't essentially related to today's topic. What we need to
focus on is the lower part of the label, called the "nutrition facts
table." It shows the energy density and proportions of the three major
energy substances in this food. From the second row down, the table
lists energy, protein, fat, carbohydrates, and sodium, with
corresponding amounts in the numbers following each row. You can
randomly pick up any packaged food to look.
Note that this content isn't the total content of the entire package -
generally, it's the content per 100g of food. This labeling has two
benefits:
First, it's convenient for calculating total energy consumed. For
example, if a food package is 500g, contains 2000 kilojoules per 100g,
and you ate half (250g), then your total energy consumption is 2000
times 2.5, equaling 5000 kilojoules. Converting this, 1 kilojoule is
approximately 1/4 calorie, so you consumed about 1250 calories.
Second, it's convenient for comparing different foods. All being 100g,
you can immediately see which food has higher energy and know how to
choose.
For imported foods, Chinese customs require Chinese labels to be
attached - just read them directly. What about products bought through
personal shoppers? No worries. Almost all countries worldwide have
these food labels with exactly the same format - just find the table
with numbers on the packaging, following the same order as Chinese
labels.
For items with labels, read the labels directly. What about unpackaged
items? For example, various fresh vegetables, fruits, meat, eggs - how
do you calculate their calories?
No problem. Many books and mobile apps have this search function,
allowing you to look up calorie counts for various foods. I'll share
some I find useful in the comments section, and welcome you to share as
well.
Step Two: Food Photography
After learning to read labels and check tables to understand a food's
energy content, the second step is recording all food you eat in a
day. This is medically called a "nutrition diary." But you don't need
to write this diary - just take photos.
From the first bite in the morning to everything eaten before bedtime,
photograph it all. For packaged items, photograph the amount eaten and
the food label; for unlabeled items, place them on a plate, take a
photo before eating, and if you don't finish, take another photo after
eating. Of course, include snacks, alcohol, beverages - anything with
energy should be photographed.
This task should be done three times before starting weight loss.
Choose one workday, one weekend day, and one special day like business
travel, gatherings, or night shifts. Eat normally for three days and
record everything.
Step Three: Create Daily Meal Plans
After completing the nutrition diary, comes the third step - pull out
all daily photos and remove 500-750 calories worth of food from them.
As mentioned earlier, carbohydrates and proteins both contain 4
calories per gram; fat is highest at 9 calories per gram. You can
calculate simply.
In specific operation, you can first reduce late-night snacks, then
sugary drinks, then snacks. If the total still doesn't reach the set
energy deficit, then reduce main meals. Stop when you've reduced a
total of 500-750 calories.
At this point, look clearly at and record the remaining food photos
from these three days. Eat according to this plan going forward. Over
time, with a stable daily energy deficit, weight will gradually
decrease.
Of course, this meal plan can be adjusted according to your
preferences. For example, equivalent vegetables can be swapped for
vegetables, fruits for fruits, meats for meats, staples for staples,
packaged foods for packaged foods - basically, equivalent exchanges
within the same category work. We'll discuss this in detail in the next
lecture. This way, this meal plan represents your preferred eating
habits, making it easier to stick to.
After reducing food, how do you know if you've reduced correctly?
The checking method is also easy - with an energy deficit of 500-750
calories, your weight should steadily decrease by 0.5-1kg weekly.
If you haven't lost this much, either you haven't reduced enough
energy, or as your weight decreases, your body's consumption becomes
smaller, the energy deficit no longer exists - meaning you've entered a
weight loss plateau. At this point, repeat steps two and three
mentioned earlier and readjust.
Key Points
1. Weight loss means creating an energy deficit.
2. Eating 500-750 fewer calories daily than currently will gradually
lead to weight loss.
3. Creating an energy deficit requires three steps: first, learn to
read food labels; second, photograph your diet; third, reduce food
intake by at least 500 calories.
4. After losing weight for a period, repeat the three steps of creating
an energy deficit to solve plateau problems.
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