OTHER DIETS: DO THEY WORK, AND ARE THERE BENEFITS OF ONE OVER THE
OTHER?
This question has received a lot of attention because of the popularity of the high-protein
diets and claims by their proponents that restricting carbohydrates and allowing an unlimited intake of proteins
and fats leads to significant weight loss.
Low-Carbohydrate Diets
Several studies have compared the Atkins type of low-carbohydrate diet with a low-fat diet,
and these studies have found that at six months, people on the lowcarbohydrate, high-protein diet had indeed
lost more weight than the people on the low-fat diets, but by twelve months both groups had lost the same amount
of weight. A significant proportion of subjects in both groups dropped out of the study by one year (up to 50
percent in some studies). Since the studies were for one year only, it is hard to determine if one diet or the
other would be detrimental to health. What was noted was that those on the Atkins diet had lower triglycerides
and higher HDL cholesterol, whereas those on the low-fat diet had lower LDL cholesterol levels. There are no
studies, however, that look at long-term benefits or hazards of the low-carbohydrate, high-protein diets, and so
the ADA does not recommend them.
If you have evidence of diabetic kidney disease, do not do the Atkins or South Beach diets
because the high protein intake may worsen the injury to the kidneys. A diet very high in animal protein
(especially red meat) and low in fiber over a long period of time may also increase the risk of gastrointestinal
problems, including colon cancer.
Why does the Atkins diet cause weight loss in the short term? It is not because a high-protein
diet leads to increased energy expenditure. It is possible that the high-protein diet is more satiating, and
therefore you eat less. The diet is also rather monotonous, and so you may eat less. This probably also explains
why patients do not continue on the diet for the long term.
Low-Fat Diets
Low-fat diets do cause weight loss, and the Ornish diet has been shown to be benefi cial in
reducing heart disease. However, in the long term, they have not been shown to be better than conventional
diets.
Very Low Calorie Diets
These diets are
recommended for people with a BMI greater than 30. The daily caloric intake is less than 800 kcals, given in the
form of liquid meals. Typically, the diet consists of 70 to 100 grams protein, 80 grams carbohydrate, and 15
grams fat, plus 100 percent of recommended daily vitamins and minerals. The weight loss is usually 3.3 to 5.5
pounds per week. Generally, people enrolling in these diets lose up to 25 percent of their initial weight in the
first three to four months. After the rapid weight loss over a three-month period, regular food is reintroduced
and weight stabilized over the next three to four months. Unfortunately, a significant number of individuals then
regain the lost weight over the next one to two years, and over the long term, these diets do not appear to be
any better than low-calorie diets with conventional food. About 25 to 50 percent of people drop out of these
programs within three to six months. Gallstones have been shown to develop with very low calorie diets—they may
occur in as many as 25 percent of patients, and about 6 percent require surgery. The risk of gallstones is
reduced if you increase the fat content of the diet,
limit weight loss to 3.3 pounds per week, and give capsules of a bile salt called ursodeoxycholic acid. Other
side effects of these diets include hair loss, headache, fatigue, dizziness, dehydration, muscle cramps, and
constipation. If you do go on a very low calorie diet, a doctor will check you every two weeks or so while you
are losing a lot of weight.
Low-Calorie Diets with Partial Meal Replacement
with Liquid Meals
These are conventional low-calorie diets (1,000 to 1,500 kcals),
but instead of regular food, one or more meals are replaced by liquid meals (Optifast or Slim-Fast). In one study,
patients were able to lose 10 percent of their excess weight and keep it off for five years using one or two meal
replacements with liquid food per day. One reason these liquid meal replacements work is because it takes the
guesswork out of estimating calories. It is clearly harder to estimate portions and caloric content of conventional
foods, and it has been shown that obese individuals tend to underestimate their caloric intake by 40 to 50 percent
when consuming conventional foods.
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