ST. LOUIS -- Carbohydrate-controlled diets appear to be a safe and
effective method of weight loss for overweight adolescents, who respond
well to this "black and white" approach to eating and to the
diets' lack of emphasis on portion control.
"Teenagers don't like to be told to count points or
calories," Dr. Stephen Sondike said at the annual meeting of the
Society for Adolescent Medicine. "They like to be told. "This
is what you can have, this is what you can't have. Now knock
yourself out.'"
The immediate feedback with such diets also appeals to adolescents,
said Dr. Sondike, director of the NEW (Nutrition, Exercise, and Weight
Management) Kids Program at Children's Hospital of Wisconsin.
Within 3 days, the patient can have a simple urine test for ketones,
which will reveal whether they're doing the diet right, he said.
While acknowledging the controversy surrounding low-carbohydrate
diets, Dr. Sondike said such eating plans do appear more effective than
low-fat or restricted-calorie diets--at least in the short term.
A number of studies--including his own study published in
2003--have shown that controlled-carbohydrate diets result in greater
initial weight loss than low-fat diets. However, he said, long-term
research indicates that after 1 year of dieting, weight loss is similar
between diets that restrict carbohydrates, fat, or calories. But a diet
that's more palatable, less restrictive, and satisfies larger
appetites, such as a controlled-carbohydrate diet, may be easier for
teens to stick to in the long run.
Dr. Sondike's study compared weight loss and lipid profiles in
30 adolescents who followed either a low-fat or a low-carbohydrate diet
for 12 weeks. The subjects were 14-15 years old with an average body
mass index of 35.5.
The low-carbohydrate group was instructed to consume less than 20 g
of carbohydrate per day for 2 weeks, and then less than 40 g per day for
10 weeks (adding fruits, nuts, and whole grains), and to eat
low-carbohydrate foods according to hunger. The low-fat group was
instructed to consume less than 30% of energy from fat. Diet composition
and weight were monitored and recorded every 2 weeks.
By the end of the trial, the low-carbohydrate group lost a mean of
9.9 pounds; the low-fat group lost a mean of 4.1 pounds. Interestingly,
Dr. Sondike said, the adolescents in the low-carbohydrate group consumed
more calories per day than those in the low-fat group (an average of
1,700 vs. 1,100), but still lost more weight.
Both groups decreased their total cholesterol levels, although the
low-fat group reduced their levels by more than the low-carbohydrate
group. (See box.) There was improvement in LDL cholesterol levels in the
low-fat group but not in the low-carbohydrate group.
"This finding may indicate that the low-carbohydrate diet
isn't appropriate for patients who may have familial elevated
LDL," Dr. Sondike cautioned. "For those patients, a low-fat
diet is probably the best recommendation. But for those whose chief
complaint is being overweight, the low-carbohydrate diet can be
considered."
Many argue that low-carbohydrate diets are simply well disguised
low-calorie diets: Restricting any food group automatically lowers
calorie consumption. But there is good evidence that decreasing
carbohydrate intake initiates a cascade of biochemical changes that lead
to fat loss, Dr. Sondike said. When blood sugar falls, there is a
corresponding rise in catecholamines. This rise, combined with an
increase in glucagon, leads to increased free fatty acids. These fatty
acids are incompletely metabolized in lieu of glucose, leading to
excretion of energy in the form of ketones. The process results in mild
acidosis.
Dr. Sondike said this state is not comparable to diabetic
ketoacidosis. "In diabetic ketoacidosis, you have 12-13 [micro]mol
of ketone body per liter. On a controlled-carbohydrate diet, you have
about 1-2 [micro]mol/L."
Lipid Levels of Adolescents On Low-Fat vs. Low-Carbohydrate Diets
Mean % Change
Low-Fat Low-Carbohydrate
Cholesterol -17.3 -3.7
Triglycerides -5.9 -48.3
LDL -25.1 3.8
HDL 1.8 3.8
Source: Dr, Stephen Sondike
BY MICHELE G. SULLIVAN
Mid-Atlantic Bureau
effective method of weight loss for overweight adolescents, who respond
well to this "black and white" approach to eating and to the
diets' lack of emphasis on portion control.
"Teenagers don't like to be told to count points or
calories," Dr. Stephen Sondike said at the annual meeting of the
Society for Adolescent Medicine. "They like to be told. "This
is what you can have, this is what you can't have. Now knock
yourself out.'"
The immediate feedback with such diets also appeals to adolescents,
said Dr. Sondike, director of the NEW (Nutrition, Exercise, and Weight
Management) Kids Program at Children's Hospital of Wisconsin.
Within 3 days, the patient can have a simple urine test for ketones,
which will reveal whether they're doing the diet right, he said.
While acknowledging the controversy surrounding low-carbohydrate
diets, Dr. Sondike said such eating plans do appear more effective than
low-fat or restricted-calorie diets--at least in the short term.
A number of studies--including his own study published in
2003--have shown that controlled-carbohydrate diets result in greater
initial weight loss than low-fat diets. However, he said, long-term
research indicates that after 1 year of dieting, weight loss is similar
between diets that restrict carbohydrates, fat, or calories. But a diet
that's more palatable, less restrictive, and satisfies larger
appetites, such as a controlled-carbohydrate diet, may be easier for
teens to stick to in the long run.
Dr. Sondike's study compared weight loss and lipid profiles in
30 adolescents who followed either a low-fat or a low-carbohydrate diet
for 12 weeks. The subjects were 14-15 years old with an average body
mass index of 35.5.
The low-carbohydrate group was instructed to consume less than 20 g
of carbohydrate per day for 2 weeks, and then less than 40 g per day for
10 weeks (adding fruits, nuts, and whole grains), and to eat
low-carbohydrate foods according to hunger. The low-fat group was
instructed to consume less than 30% of energy from fat. Diet composition
and weight were monitored and recorded every 2 weeks.
By the end of the trial, the low-carbohydrate group lost a mean of
9.9 pounds; the low-fat group lost a mean of 4.1 pounds. Interestingly,
Dr. Sondike said, the adolescents in the low-carbohydrate group consumed
more calories per day than those in the low-fat group (an average of
1,700 vs. 1,100), but still lost more weight.
Both groups decreased their total cholesterol levels, although the
low-fat group reduced their levels by more than the low-carbohydrate
group. (See box.) There was improvement in LDL cholesterol levels in the
low-fat group but not in the low-carbohydrate group.
"This finding may indicate that the low-carbohydrate diet
isn't appropriate for patients who may have familial elevated
LDL," Dr. Sondike cautioned. "For those patients, a low-fat
diet is probably the best recommendation. But for those whose chief
complaint is being overweight, the low-carbohydrate diet can be
considered."
Many argue that low-carbohydrate diets are simply well disguised
low-calorie diets: Restricting any food group automatically lowers
calorie consumption. But there is good evidence that decreasing
carbohydrate intake initiates a cascade of biochemical changes that lead
to fat loss, Dr. Sondike said. When blood sugar falls, there is a
corresponding rise in catecholamines. This rise, combined with an
increase in glucagon, leads to increased free fatty acids. These fatty
acids are incompletely metabolized in lieu of glucose, leading to
excretion of energy in the form of ketones. The process results in mild
acidosis.
Dr. Sondike said this state is not comparable to diabetic
ketoacidosis. "In diabetic ketoacidosis, you have 12-13 [micro]mol
of ketone body per liter. On a controlled-carbohydrate diet, you have
about 1-2 [micro]mol/L."
Lipid Levels of Adolescents On Low-Fat vs. Low-Carbohydrate Diets
Mean % Change
Low-Fat Low-Carbohydrate
Cholesterol -17.3 -3.7
Triglycerides -5.9 -48.3
LDL -25.1 3.8
HDL 1.8 3.8
Source: Dr, Stephen Sondike
BY MICHELE G. SULLIVAN
Mid-Atlantic Bureau