|
 Although
there seems to be little doubt that overweight individuals have increased
risk for morbidity and mortality, it does not immediately follow that
weight loss reduces that increased risk. Understanding the health consequences
of weight loss requires data on what happens to those who have lost weight.
Such data should derive from either observational studies of persons
who by self-report or measurement have lost weight or clinical trials
in which how the weight was lost is known. Much of the longer term data
come from observational studies because follow-up in trials has generally
been short; however, clinical trials would provide clearer evidence of
the relationship between weight loss and health.
The incidence and severity of noninsulin-dependent diabetes mellitus
and hypertension in overweight persons are reduced by weight loss. Recent
studies have shown that a diet and exercise program leading to weight
loss can prevent the onset of hypertension and that the same may be true
for diabetes mellitus. Persons with diabetes who can lose weight will
improve glycemic control and may eliminate their need for oral agents.
Similarly, randomized trial data indicate that weight loss in hypertensive
patients is also associated with significant reductions in blood pressure
and the need for continued drug therapy. Weight loss also affects other
risk factors for cardiovascular disease: The positive effects on lipid
and lipoprotein levels are well documented. Given the high likelihood
that weight will be regained, it remains to be determined whether these
time-limited improvements confer more permanent health benefits.
Among very obese individuals, weight loss has been followed by greater
functional status, reduced work absenteeism, less pain, and greater social
interaction. The prevalence and severity of sleep apnea also can be substantially
reduced by weight loss, but monitoring for weight regain is important.
Very-low-calorie diets and fasting are associated with a variety of
short-term adverse effects. Patients frequently report fatigue, hair
loss, dizziness, and other symptoms, but these appear to be transitory.
More serious is the increased risk for gallstones and acute gallbladder
disease during severe calorie restriction. Serious complications such
as cardiac arrhythmias or death, seen in early studies, have largely
been eliminated by enriching diets with high-quality protein, minerals,
and electrolytes.
Data on short-term adverse health effects of weight loss come from programs
that only include overweight persons. Some of these effects may be greater
in persons who are not overweight but are severely restricting calories.
Laboratory evidence suggests that weight loss in lean persons leads to
a greater proportional loss of lean body mass than in severely overweight
persons and may well increase adverse effects such as fatigue.
Participants in formal weight loss programs may reduce baseline depression
and anxiety, but only if they successfully lose weight. Little is known
about the emotional impact of lesser degrees of success or of failure.
There also is increasing evidence that mildly to moderately overweight
women who are dieting may be at risk for binge- eating without vomiting
and purging. Whether involvement in a well- designed dietary modification
program increases the risks for bulimia is unknown and in need of careful
study.
The evidence that reductions in mortality follow weight loss is meager.
Most epidemiologic studies suggest that weight loss is associated with
increased mortality, although in most of these studies the reason for
weight loss is not known. Intentional weight loss during healthy states
cannot be distinguished from that associated with illness, psychosocial
distress, or other reasons. Finally, the fact that many people who stop
smoking gain weight complicates the interpretation of the data on weight
gainers and weight losers. Thus, although the data on higher mortality
are provocative, they are not sufficiently conclusive to dictate clinical
practice. Specific research efforts to address this question are urgently
needed.
Data on the health effects of repeated weight gains and losses, or weight
cycling, are also inconclusive. Weight cycling appears to affect energy
metabolism and may result in faster regaining of weight, but the evidence
that cycling has longer term negative effects on psychological and physical
health needs confirmation.
Although currently used weight-reducing drugs appear to be safe in controlled
studies, the studies are short term and have involved populations where
the potential for abuse may be low. The fact that many adolescents and
young adults use over-the-counter preparations urges further study of
their safety in real-world use.
Understanding of the likelihood of success is a key element in making
informed choices from among the dietary, exercise, and behavioral options
for weight loss. In this section, these various weight loss methods are
discussed with respect to their effectiveness in facilitating weight
loss.
For most weight loss methods, there are few scientific studies evaluating
their effectiveness and safety. The available studies indicate that persons
lose weight while participating in such programs but, after completing
the program, tend to regain the weight over time. Further, there are
examples where weight loss strategies have caused medical harm. Thus,
the panel cautions that before individuals adopt any weight loss program,
the scientific data on effectiveness and safety be examined. If no data
exist, the panel recommends that the program not be used. The lack of
data on many commercial programs advertised for weight loss is especially
disconcerting in view of the large number of Americans trying to lose
weight and the over $30 billion spent yearly in America on weight loss
efforts. Some research data and considerable anecdotal information support
successful short-term loss for some users of these programs; however,
data are limited on the proportion of persons who complete programs,
how much weight they lose, and their success in maintaining the weight
loss.
Considerable diversity in response exists within each of the broad categories
of weight loss strategies. Success rates can be expected to vary according
to initial weight, the length of the treatment period, the magnitude
of weight loss desired, and the motivation for wanting to lose weight.
The effectiveness of unsupervised efforts to lose weight is difficult
to judge because of limited data on strategies, compliance, and follow-up.
Surveys indicate that many overweight persons have tried to lose weight
on multiple occasions; because many of these persons presumably are using
these unsupervised strategies, their long-term success rates may be low.
Dietary Change
Dietary change is the most commonly used weight loss strategy. Methods
range from caloric restriction to changes in dietary proportions of fat,
protein, and carbohydrate or use of macronutrient substitutes. Short-
term success for some of these methods has been documented, but information
on long-term effectiveness and safety up to 5 years is limited. Appropriate
dietary programs can have positive health effects on factors other than
weight loss.
Weight loss at the end of relatively short-term programs can exceed
10 percent of initial body weight; however, there is a strong tendency
to regain weight, with as much as two thirds of the weight lost regained
within 1 year of completing the program and almost all by 5 years. Importantly,
however, a small percentage of participants do maintain their weight
loss over more extended periods. Key aspects of the evaluation of programs
are their duration and dropout rates. The duration of most programs appears
to be from several weeks to a few months. Dropout rates can be as high
as 80 percent and seem to vary considerably.
Two levels of caloric restriction are commonly used. The low-calorie
diet (LCD) of about 1,000 to 1,500 calories (approximately 12 to 15 Kcal/kg
body weight) per day may involve a structured commercial program with
formulated and calorically defined food products or guidelines in selecting
conventional foods. The very-low-calorie diet (VLCD) at 800 (approximately
6-10 Kcal/kg body weight) or fewer calories per day is conducted under
physician supervision and monitoring and is restricted to severely overweight
persons. Both diets may produce adverse side effects, including excessive
loss of lean body mass. Attempts to use VLCD's in unsupervised settings
have been associated with severe complications. In the short term, VLCD's
produce greater weight loss than do LCD's; however, with both types of
programs, participants tend to return to preprogram weight within 5 years.
There is evidence that altering the proportion of the calories in the
diet from fat, carbohydrate, and protein can have a limited effect on
weight loss; however, the effects appear to be quite small in comparison
with the direct effect of caloric restriction.
Vitamin & Mineral Supplementation
The following dietary supplements can facilitate immediate weight loss:
| Supplement |
Dose |
| CLA (76%) 1000 mg or CLA with Guarana extract |
3-5 capsules early in the day 3-5 capsules early in the day |
| Chromium (picolinate or polynicotinate) |
200 mcg, 1 capsule with each meal |
| Super GLA/DHA (essential fatty acids) |
6 capsules per day |
| A Multi-Vitamin that provides adequate doses of magnesium, zinc,
and other important nutrients |
As recommended on the product packaging |
| Fiber (psyllium seed, guar, and pectin) |
Start with 4 grams taken when high-fat meals are consumed. Do not
take with CLA or Super GLA/DHA because fiber will bind to these important
fatty acids before they can be absorbed into the bloodstream |
| Lecithin is a fat emulsifier and enables fats and cholesterol to
be removed from the body. |
As recommended on the product packaging |
Exercise
 Weight
loss that can be achieved by exercise programs alone is more limited
than that which can be obtained by caloric restriction. However, exercise
has beneficial effects independent of weight loss, including increased
high-density lipoprotein cholesterol and an increase in lean body mass.
Further, exercise can be an important adjunct to other strategies and
can, if continued, diminish the tendency for rapid postprogram weight
gain. The amount of weight lost through exercise usually ranges from
4 to 7 pounds. This amount is usually in addition to that lost through
caloric restriction.
Behavior Modification
Behavior modification involves:
- Identifying eating or related life- style behaviors to be modified
- Setting specific behavioral goals
- Modifying determinants of the behavior to be changed
- Reinforcing the desired behavior
The goal of behavior treatment is to modify eating and physical activity
habits, typically focusing on gradual changes. Behavior modification
can be undertaken through group or individual sessions, under the guidance
of professional or lay personnel, and alone or in conjunction with other
approaches.
When used alone, the typical program takes about 18 weeks and can generate
a 1- to 1.5-pound/week weight loss. Typically about one third of this
weight will be regained at the end of 1 year and most regained by 5 years.
As with other methods, however, a small percentage of participants are
able to maintain weight loss over an extended period.
Drug Treatment
In carefully controlled research programs, treatment with investigational
drugs has been effective in producing weight loss. Combined with some
degree of caloric restriction, weight loss with these drugs can be equivalent
to that from VLCD's over comparable periods. Some studies show that prolonging
use can result in a slowing of weight loss and eventually a weight plateau.
Long-term benefits and complications need to be evaluated.
Phenylpropanolamine, an over-the-counter appetite suppressant approved
by the Food and Drug Administration, has some efficacy in producing weight
loss. The long-term benefit of this drug is not well documented, and
as with other over-the-counter preparations, there is potential for its
misuse.
Combination Therapies
Dietary and exercise changes, and these changes reinforced by behavior
modification, are the most frequently used combination therapies. Combining
changes in diet and exercise can lead to greater short-term weight loss
than changes with either alone. Further, behavior modification appears
to help extend the interval before weight is regained, especially if
contact between the program deliverers and participants is continued
and maintenance strategies are used.
Attributes and Barriers
In general, successful programs are those based on realistic goals that
involve a caloric deficit leading to a slow, steady weight loss. Success
requires a diet that can be adhered to long enough to reach the goal.
Developing new dietary practices that could lead to a lifetime of weight
control is also important. Other attributes of successful programs involve
preparing the person to deal with high-risk emotional and social situations,
self-monitor progress, solve problems, reduce stress, and maintain continual
professional contact. Barriers to success include lack of feelings of
self-efficacy, failure to lose weight early, premature termination of
diet modifications or exercise or both, and lack of social and professional
support. Serious underlying social or psychological problems such as
depression also can be barriers to success.
The effectiveness of the different weight loss programs may vary among
different cultural groups; however, the data to evaluate this possibility
are limited. As these programs are studied further, it is important to
consider that some may also be effective in preventing overweight. |
Anorexia
