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Back to Weight Reduction Techniques
Diet Reduction
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For good health we require energy-providing nutrients (protein, fat, and
carbohydrate), vitamins, minerals, and water. |
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No matter what diet you are on, if you eat less and lose weight you
also lower your risk of heart disease and lead a healthier life.
Caloric intake is the cornerstone of obesity treatment. The fundamental
goal is the sustained reduction of energy intake below that of energy expenditure.
A wide variety of suggested diets exist that are designed to achieve this.
The main diet regimens in use follow several general facts relevant to food
intake and weight loss.
First, a deficit of 7500 kcal will produce a weight loss of approximately
1 kg. Therefore, eating 100 kcal/d less for a year should cause a 5-kg weight
loss, and a deficit of 1000 kcal/d should cause a loss of approximately
1 kg per week. The rate of weight loss on a given caloric intake is related
to the rate of energy expenditure.
Obese individuals have a higher metabolic rate than lean individuals,
and men have a higher metabolic rate than women (due to their greater lean
body mass); thus, the rate of weight loss is greater among the more obese
and among men (relative to women). With chronic caloric restriction, metabolic
rate diminishes, but because of reduced lean body mass (along with much
greater loss in fat mass) and possibly because of other adaptations. This
fall in metabolic rate with food restriction slows the rate of weight loss
on a constant diet.
For information on common diet plans (Atkins,
Ornish.. etc) click here!
Very low energy diets
Very low energy diets (e.g., 400 to 600 kcal/d) are widely used. The
liquid protein diets popularized in the 1970s were proved to be unsafe,
causing >60 deaths. Life-threatening arrhythmias were documented in the
clinical research setting, a consequence of both low-quality protein and
deficiencies of vitamins, minerals, and trace elements. These types of diets
have now been substantially modified. A very low energy diet consisting
of 45 to 70 g high-quality protein, 30 to 50 g carbohydrate, and approximately
2 g fat per day, as well as supplements of vitamins, minerals, and trace
elements, appears to be safe in selected patients under medical supervision.
Patients should not be started on such diets unless they are >130% of their
ideal body weight. Contraindications include pregnancy, cancer, recent myocardial
infarction, cerebrovascular disease, hepatic disease, or untreated psychiatric
disease. When used in patients with diabetes who are receiving insulin or
oral agent therapy, close supervision is required and diabetic treatment
may need to be adjusted. Whenever possible, exercise regimens and behavioral
modification approaches should be used in conjunction with the diet.
Advantages of very low calorie diets are the greater rate of weight loss
compared to less restrictive diets, as well as the possible beneficial effect
of hunger suppression brought about by the production of ketones. In patients
on such diets, blood pressure, blood glucose, cholesterol, and triglyceride
levels fall, and pulmonary function and exercise tolerance improve. Sleep
apnea may improve within a few weeks. Complications of these very low energy
diets are usually minor and include fatigue,
constipation or
diarrhea, dry
skin, hair loss, menstrual irregularities, orthostatic dizziness, and difficulty
concentrating. Cholelithiasis and pancreatitis may occur when such diets
are interrupted by binge eating; gallstones have been shown to develop in
as many as 25% of patients while on the diet.
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Low energy diets
Low-calorie diets,>800 kcal/d, are applicable to most patients and have
fewer restrictions than the very low calorie diets. Considerable controversy
has attended the question of which diet composition is most appropriate
for promoting weight loss. Though commonly recommended, benefits resulting
from very low fat diets are modest at best. Nonetheless, the health effects
of low-fat diets -- apart from curbing obesity -- may be important. A diet
rich in fruits, vegetables, and whole grains may promote weight loss and
is preferable to low-fat diets in which large amounts of simple carbohydrates
are substituted for fats. The latter may actually promote obesity. Some
have advocated diets with protein replacement of simple carbohydrates in
an effort to minimize insulin production. The efficacy of this strategy,
aside from overall calorie reduction, is unknown.
High carbohydrate diets
The name of this diet is based on the concept that
if you eat a very high starch/high fibre diet, you can actually eat a greater
total weight of food than usual, and still lose body fat. As a result the
diet advocates extremely high carbohydrate intake.
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