By Jacquie Craig, M.S., R.D., C.D.E. | June 5, 2008 12:00 am
Anybody who has tried to lose weight knows how difficult it can be. But for many people, the initial weight loss isn’t the hardest part: Keeping it off over time is even more of a challenge.
In an effort to understand why this is so and what might help people maintain their weight loss, researchers have studied this issue from numerous angles. Some research has focused on hormones in the body that influence appetite, some on environmental cues to eat or to refrain from overeating, some on drugs to help with weight loss, and some on the self-reported habits of people who have lost weight and kept it off.
This article takes a look at some of the reasons it can be hard to maintain weight loss and what research has shown that might be of practical help to those who are trying to do just that.
There are many factors working against a person who is trying to maintain weight loss. These hurdles may be metabolic, hormonal, and environmental.
Metabolic hurdles. One of the ironies of weight loss is that the more you lose, the harder you have to work to lose more. This is in part because the body’s metabolism slows down—meaning it burns less energy, or fewer calories—both at rest and during exercise following weight loss. Some studies suggest that the decrease in amount of energy burned may be more pronounced in people who were previously obese than in those who were never obese. However, it is not clear that this increased metabolic slowdown is permanent, nor that it necessarily hinders weight maintenance efforts.
Hormonal influences. Various hormones help regulate hunger and fullness. Leptin, which is made from fat cells, tells the brain when a person is full. At first, obesity researchers thought that leptin might be useful as a treatment for obesity. However, it was found to be effective only in a small percentage of obese people who do not produce their own natural leptin (a rare genetic disorder). Many obese people have naturally high levels of leptin and do not respond to leptin injections by eating less or losing weight. In fact, it is believed that many obese people are “leptin resistant” in much the same way as people with Type 2 diabetes are insulin resistant. Research is ongoing to determine what causes leptin resistance and how it might be treated or circumvented.
Ghrelin, which is released mainly in the stomach, stimulates appetite. Its level rises between meals and falls sharply after eating. Some studies have shown increased ghrelin levels in obese people who have lost weight through dietary changes. It is not clear whether levels eventually return to normal during weight maintenance. In contrast, however, studies have found decreased ghrelin levels in people who have had gastric bypass surgery to treat obesity. Reduced ghrelin levels may contribute to the success of maintaining weight loss after this surgery.
A few small studies have examined whether the proportions of fat, carbohydrate, and protein in a meal influence ghrelin levels after the meal in healthy adults. While all the meals in the studies lowered ghrelin levels somewhat, the higher-protein meals suppressed ghrelin for the longest amount of time.
Getting too few hours of sleep at night can lower leptin levels, raise ghrelin levels, and increase hunger and appetite. Getting enough sleep, therefore, may help to control hunger and appetite and, consequently, weight gain or regain.
Insulin is another hormone of interest to people with diabetes. Produced by the pancreas, insulin helps your body store and use glucose. However, in Type 1 diabetes, the pancreas no longer secretes insulin, and in Type 2 diabetes, insulin production typically declines over the years, and many people with Type 2 diabetes eventually need to supplement the insulin their body makes with injected, infused, or inhaled insulin.
No matter what type of diabetes a person has, the initiation of insulin therapy is often accompanied by some weight gain. This is because calories from glucose that were once being excreted in the urine are now being stored in the body’s cells. It may also be because a person is feeling better and has more of an appetite. In a person who lost a lot of body weight before his diabetes diagnosis, a certain amount of weight gain when starting insulin therapy may be healthy, but a person who is not underweight may need to cut back on calories to prevent weight gain.
While very high blood glucose can lead to weight loss as glucose is excreted in the urine, it can also cause feelings of tiredness and increased hunger, which can lead to decreased activity, increased eating, and over time (assuming there is not a complete absence of insulin), weight gain. Having an effective plan to manage blood glucose levels—whether with insulin or by other means—is therefore an important part of weight control for people with diabetes.
Environmental challenges. A person who is actively losing weight is often the recipient of praise and compliments from family members, friends, and colleagues. Many people also enjoy the excitement of fitting into smaller clothes sizes as they lose weight. These types of positive reinforcement can help a person who is actively losing weight to stay motivated to continue with the healthful lifestyle changes that enable him to lose more weight.
Once a person’s weight has stabilized, however, the compliments from others may become less frequent, and the person himself may start to take his smaller clothes size and improved blood pressure, blood cholesterol, and blood glucose levels for granted. When this happens, a person must find new positive reinforcements to feel motivated to keep up his good habits and maintain his weight loss year after year. One of the places in which such reinforcement may be found is in a weight-loss support group, where others are facing the same issues and understand how challenging weight maintenance can be.
Some other factors in a person’s environment that can pose a challenge to weight maintenance are food packaging and restaurant serving sizes, both of which influence how much a person eats. Serving sizes of foods and beverages started rising in the 1970’s and have paralleled the obesity epidemic over the past 36 years. Many studies suggest that the larger the portion served or purchased, the more of it a person consumes. In one study, people who were served soup in invisibly self-refilling bowls ate 73% more soup than those eating from normal soup bowls. Interestingly, the people who ate more soup did not believe they had consumed more, nor did they feel more sated than those eating from normal bowls. In another study, participants consumed 30% more macaroni and cheese at lunch when offered a larger portion.
These are important findings to remember when eating out, since restaurants today tend to serve larger portions of food than in years past, as well as foods with greater calorie density. As a result, frequently dining out or buying take-out food from restaurants can make maintaining weight loss more challenging. People who do eat out frequently need to learn strategies to keep their calories in check, such as eating just half of the food served (and saving the other half for a second meal) and limiting higher-calorie menu selections such as deep-fried, creamy, or cheesy items.
Since losing weight and keeping it off is so difficult for so many people, it’s worth asking whether making the effort has actual benefits. In the short term, weight loss is known to improve sleep apnea (the repeated cessation of breathing during sleep), lower high blood pressure, and improve blood cholesterol and triglyceride levels. But does long-term weight loss have long-term benefits, such as a lowered risk of chronic disease or a longer life?
Several studies have shown that long-term weight loss lowers blood pressure in people who are obese, and high blood pressure is a known risk factor for heart attacks and strokes. In one study, obese subjects who lost weight and maintained their weight loss over a four-year period had significantly lower blood pressure at the end of the study than when they started the study. Another study found similar results after following overweight or obese subjects who lost a modest amount of weight over a three-year period.
Good information on the long-term benefits of weight loss for people with diabetes should be available in about five years. In 2001, a 12-year, randomized, clinical trial called “Look AHEAD: Action for Health in Diabetes” was started involving 5,000 people with Type 2 diabetes who were either overweight or obese at the beginning of the study. The goal is to have the people in the treatment group lose 7% to 10% of their body weight and maintain that weight loss throughout the study. The researchers will observe how long-term weight loss affects blood pressure, blood cholesterol and other lipids (fats in the blood), diabetes control, and the incidence of heart attacks and stroke.
Guidelines issued by the National Heart, Lung, and Blood Institute and the North American Association for Study of Obesity recommend a comprehensive program of diet, exercise, and behavior therapy for the management of obesity. All three of these components need to be sustained for a lifetime for weight loss to be permanent. So no matter what particular path you take to lose weight—and there are many programs out there, both commercial and noncommercial, to assist with weight loss—choosing a route that addresses all three will help you succeed at weight loss and increase your chances of keeping the weight off for the long term.
One source of information on weight loss that is being studied in a systematic way is the National Weight Control Registry, which is a voluntary registry of people who have lost at least 30 pounds of excess weight and kept it off for at least a year. People who enroll are periodically asked to complete questionnaires about their success at losing weight, current weight maintenance strategies, and other health-related behaviors. (To learn more about the registry or to join it, log on to www.nwcr.ws or call  606-NWCR .) The hope is that others can learn from those who have succeeded.
There are currently more than 5,000 people in the registry, which was started in 1994. The average participant has lost 60 pounds and has maintained that loss for five years. Approximately 50% of the people in the registry lost the weight on their own, without the help of an outside program. To maintain their weight loss, people in the registry continue to pay attention to diet and get an average of 60 minutes a day of physical activity, with walking being the most frequently reported form of exercise. Most registry members report improvements in their energy, mobility, mood, self-confidence, and physical health after losing weight.
As far as diet is concerned, those in the registry tend to follow a low-calorie, low-fat diet. In a survey of 355 women and 83 men published in 1998, the women in the registry reported consuming an average of 1,306 calories per day (24.3% calories from fat) and the men 1,685 calories per day (23.5% calories from fat). For an idea of what these calorie levels look like in actual food, see “Maintenance Meal Plans.”
A study of registry members published in 1999 examined why some people gain back weight they have lost. Factors making regain of lost weight likely included having lost weight more recently (less than 2 years before the survey), having lost a large amount of weight (more than 30% of maximum body weight), depression, and binge eating disorder. Those who regained weight reported getting less physical activity and eating a higher-fat diet than those who maintained their weight loss.
A third study, published in 2006, examined the effects of three strategies designed to help with weight maintenance. The study subjects were 314 people who had lost 10% of their body weight in the previous two years. One group (the “control” group) received a quarterly newsletter with information about diet, exercise, and weight control. Members of the other two groups were each given a scale with instructions on how to use it. Both groups reported their weight on a weekly basis by phone or via the Internet and received rewards, encouragement, and additional weight-loss tools depending on whether they maintained their weight or gained weight. One of these groups (the “face-to-face” group) attended first weekly then monthly meetings at a clinic for 18 months. The other group (the “Internet” group) used laptop computers to participate in similar meetings in chat rooms (in which messages are typed and appear on the computer screen).
Compared to the control group, the two other groups regained less weight, with the participants of the face-to-face group regaining the least. The researchers concluded that daily weighing improved maintenance of weight loss and that the type of education and support that their study provided worked best in a face-to-face format.
In some cases, certain drugs can help with weight loss and maintenance, although it should be noted that all weight-loss drugs are intended to be used along with a program of diet and exercise, not in place of diet and exercise.
In the United States, there are two prescription medicines approved for long-term use in the treatment of obesity: orlistat (brand name Xenical), and sibutramine (Meridia). In June 2007, a lower-dose version of orlistat, marketed under the brand name Alli, became available over the counter for use in adults age 18 and over.
Orlistat helps with weight loss by blocking the absorption of some of the fat a person eats. While few studies have looked at the use of orlistat beyond two years, a large, four-year study published in the journal Diabetes Care in 2004 looked at the effectiveness of using orlistat along with lifestyle changes in the prevention of Type 2 diabetes. The 3,304 study subjects were obese at the start of the study, and some had impaired glucose tolerance (which is now called prediabetes), while others did not. All were prescribed a reduced-calorie diet, given dietary counseling, and encouraged to walk at least one extra kilometer (0.62 mile) a day beyond their usual physical activity. Some additionally took orlistat, while others took a placebo (a pill with no active ingredient).
After four years, the subjects taking orlistat had lost more weight than those taking the placebo. In addition, fewer participants with prediabetes who were taking orlistat developed Type 2 diabetes. Participants taking orlistat also had significant improvements in blood pressure, waist circumference, and blood lipid levels.
Sibutramine works by directly targeting the brain. It reduces appetite by increasing the amount of time two neurotransmitters (noradrenaline and serotonin) have to act by preventing them from being reabsorbed by the brain cells (neurons) that produce them. It is believed that this effect increases feelings of fullness. Use of sibutramine has been shown to result in a 5% to 10% reduction in a person’s body weight.
Modest increases in heart rate and blood pressure can result from sibutramine use early in the course of treatment, so it’s currently recommended that blood pressure be closely monitored in people taking sibutramine and that people with serious cardiovascular problems not take it. Other side effects may include dry mouth, insomnia, loss of appetite, constipation, and headache.
While they can be effective, weight-loss medicines can also be expensive, even with prescription drug insurance coverage. This, obviously, limits their availability to some people.
Exenatide (brand name Byetta) is a fairly new injectable drug approved for the treatment of Type 2 diabetes that may cause weight loss in addition to improving blood glucose control. Byetta mimics the action of a hormone known as glucagon-like peptide-1. When blood glucose levels are high, Byetta signals the pancreas to release insulin. It also suppresses the release of glucagon, a hormone that signals the liver to release glucose. Byetta additionally slows the rate at which food moves through the stomach so that it is digested more slowly, and glucose from carbohydrate-containing foods is therefore released more slowly into the bloodstream.
Two studies reported in the professional journal Diabetes, Obesity and Metabolism found that Byetta produced a sustainable weight loss over a 20-month period. Overweight and obese subjects with Type 2 diabetes lost an average of 10–12 pounds after 20 months of Byetta use. Mild to moderate nausea was the most common side effect reported, but it tended to decrease over time. If you are interested in using Byetta as part of your Type 2 diabetes control regimen, speak to your doctor.
Just as blood glucose control requires an individualized approach, so does losing weight and maintaining that weight loss. However, there are some tools that appear to help a broad spectrum of people, such as daily weighing; maintaining a low-calorie, low-fat diet; getting at least 60 minutes of physical activity a day; getting enough sleep; learning to reward yourself when goals are achieved; and getting support from others facing the same challenges. (See “Top 5 Tips for Maintaining Weight Loss” for more information on how to become a maintainer.) The key, then, is finding ways to tailor these tools to your unique situation.
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