DIETS
Low-carb diets
Low-carb diets
Proponents of “low-carb” diets claim that
limiting our consumption of carbohydrates can
help us to lose weight and avoid the side effects
of eratically fluctuating blood-sugar levels.
How it works
In low-carb diets, instead of carbohydrates providing the main
source of calories and energy, fats and proteins do. It is claimed
that by keeping our blood sugar and insulin levels low, we can
train our body to burn its stores of fat. Also, since low-carb diets
are high in protein, and protein helps us to feel full for longer,
this enables us to eat smaller portions, reduce snacking between
meals, and cut down our overall calorie intake.
What to eat?
Anyone planning to significantly
reduce one of the main food groups
needs a diet strategy that will
compensate. While protein-rich foods and
natural fats can replace carbohydrates as
sources of energy, high-protein diets often
lack fiber, which is essential for healthy
digestion and maintaining good cholesterol
levels. Including generous servings of
vegetables such as broccoli, cauliflower,
and lettuce in your diet can boost fiber
intake, contribute micronutrients,
and add bulk to meals.
LOW-CARB DIETS CAN
HELP PEOPLE WITH
DIABETES IN THE
SHORT-TERM
CONTROL OF
BLOOD-SUGAR
LEVELS
B
R
A
I
N
C
E
L
L
L
I
V
E
R
B
R
E
A
K
F
A
S
T
L
U
N
C
H
F
A
T
C
E
L
L
M
U
S
C
L
E
C
E
L
L
Stored fatty acid
Ketone body
produced from
fatty acids in
the liver
Ketone body
being used for
energy in a
brain cell
Fatty acid being
used for energy
in muscle cell
Daily diet
By combining protein-rich foods with bulky
low-carb vegetables it is relatively easy to
eliminate carbohydrate-rich foods such as
pasta, bread, rice, and sugary foods from
each meal of the day.
Releasing fatty acids
When blood glucose levels are
maintained at a healthy level, insulin levels
remain low. This allows the release of fatty
acids from fat cells into the bloodstream,
which are then used for energy in most cells.
1
State of ketosis
Unlike other tissues,
the brain can’t use fatty
acids as an energy source.
So when blood glucose is
low, the liver converts fatty
acids into ketone bodies—
molecules that provide
energy for brain cells.
2
OMELET
SPINACH
Egg-based meal
with a high
proportion of
protein
Fatty acid
released into
bloodstream
Fat burning
By reducing the levels of glucose in
our bloodstream, we can force our
body into using alternative sources
of energy. A sustained lack of glucose
can lead to ketosis, a state in which
the body burns its stores of fat at
a very high rate.
US_196-197_Low-Carb_Diet.indd 196 18/01/2017 09:47
196
DIETS
Low-carb diets
197
Some low-carb diets are very restrictive, and as
well as cutting out foods that are obviously rich
in carbohydrates, such as pasta and bread, they
limit the intake of many other foods, at least at
first. These include all fruit and sweet-tasting
vegetables such as peas and corn. Potatoes
and other starchy vegetables including
squash, carrots, parsnips, beets, and lentils
are restricted, as are whole grains including
quinoa and oats. However, many of these
foods are key sources of fiber, vitamins, and
minerals, which are essential in a healthy diet.
LIMITED FOODS
B
R
E
A
K
F
A
S
T
L
U
N
C
H
D
I
N
N
E
R
S
N
A
C
K
Benefits
• Research is mixed as to whether these diets will help
you lose weight
• Protein-containing foods, including meats, are often
more expensive
• Eating too much animal protein may increase your risk
of developing heart disease and some cancers
Drawbacks
MODERATE HIGH-
PROTEIN DIETS
EXTREME HIGH-
PROTEIN DIETS
• A very restrictive diet is difficult to stick to, especially
when socializing
• Cutting out food groups can lead to a lack of
essential vitamins and minerals
• Lack of fiber can cause constipation
• Reliance on animal proteins may put you at risk of
diseases including heart disease and some cancers
• Cholesterol levels may increase
• Kidney problems can become worse as the kidneys
have to deal with more protein
• May be ineffective if calories aren’t restricted
• Protein keeps you full for longer so
you are unlikely to become hungry
• Lots of popular foods, including meat,
cheese, and butter are unrestricted
• Many extreme diets don’t involve the
need to count calories
• Protein helps you feel full for longer so you
may be less likely to snack between meals
• A high-protein diet during weight loss can
help you lose fat rather than muscle
• Protein takes more energy to digest, so
some of the calories will be burned off
SQUASH
BEET
WHAT IS THE
CONSENSUS ON
LOW-CARB DIETS?
Although most medical
organizations recognize the
effectiveness of low-carb diets
for weight loss, very few, if
any, recommend them as
a long-term health
strategy.
TUNA
SALAD
CHICKEN
BREAST
CAULIFLOWER
BROCCOLI
CHEESE
NUTS
Low-calorie,
low-carb salad
makes up the
bulk of the meal
Dinner lacks
high-carb foods
such as pasta
and potatoes
High-protein,
high-fat snacks are
eaten instead of
wheat-based snacks
High-protein diets
Low-carb diets are, by
definition, often also high-
protein diets. Moderate
high-protein diets
increase protein intake
above the standard
recommended amount—
around 15 percent of
total calories. They
continue to allow other
food groups, including
carbohydrates. More
extreme high-protein
diets dramatically restrict
carbohydrate intake.
Some also encourage
high fat intake.
US_196-197_Low-Carb_Diet.indd 197 18/01/2017 09:47
196
DIETS
Low-carb diets
197
Some low-carb diets are very restrictive, and as
well as cutting out foods that are obviously rich
in carbohydrates, such as pasta and bread, they
limit the intake of many other foods, at least at
first. These include all fruit and sweet-tasting
vegetables such as peas and corn. Potatoes
and other starchy vegetables including
squash, carrots, parsnips, beets, and lentils
are restricted, as are whole grains including
quinoa and oats. However, many of these
foods are key sources of fiber, vitamins, and
minerals, which are essential in a healthy diet.
LIMITED FOODS
B
R
E
A
K
F
A
S
T
L
U
N
C
H
D
I
N
N
E
R
S
N
A
C
K
Benefits
• Research is mixed as to whether these diets will help
you lose weight
• Protein-containing foods, including meats, are often
more expensive
• Eating too much animal protein may increase your risk
of developing heart disease and some cancers
Drawbacks
MODERATE HIGH-
PROTEIN DIETS
EXTREME HIGH-
PROTEIN DIETS
• A very restrictive diet is difficult to stick to, especially
when socializing
• Cutting out food groups can lead to a lack of
essential vitamins and minerals
• Lack of fiber can cause constipation
• Reliance on animal proteins may put you at risk of
diseases including heart disease and some cancers
• Cholesterol levels may increase
• Kidney problems can become worse as the kidneys
have to deal with more protein
• May be ineffective if calories aren’t restricted
• Protein keeps you full for longer so
you are unlikely to become hungry
• Lots of popular foods, including meat,
cheese, and butter are unrestricted
• Many extreme diets don’t involve the
need to count calories
• Protein helps you feel full for longer so you
may be less likely to snack between meals
• A high-protein diet during weight loss can
help you lose fat rather than muscle
• Protein takes more energy to digest, so
some of the calories will be burned off
SQUASH
BEET
WHAT IS THE
CONSENSUS ON
LOW-CARB DIETS?
Although most medical
organizations recognize the
effectiveness of low-carb diets
for weight loss, very few, if
any, recommend them as
a long-term health
strategy.
TUNA
SALAD
CHICKEN
BREAST
CAULIFLOWER
BROCCOLI
CHEESE
NUTS
Low-calorie,
low-carb salad
makes up the
bulk of the meal
Dinner lacks
high-carb foods
such as pasta
and potatoes
High-protein,
high-fat snacks are
eaten instead of
wheat-based snacks
High-protein diets
Low-carb diets are, by
definition, often also high-
protein diets. Moderate
high-protein diets
increase protein intake
above the standard
recommended amount—
around 15 percent of
total calories. They
continue to allow other
food groups, including
carbohydrates. More
extreme high-protein
diets dramatically restrict
carbohydrate intake.
Some also encourage
high fat intake.
US_196-197_Low-Carb_Diet.indd 197 18/01/2017 09:47
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