Obesity Causes, Risk Factors, Treatment, Statistics, Prevention (original) (raw)

What is obesity and overweight?

In the U.S., obesity has reached epidemic proportions.

Obesity is defined as having excess body fat, or a BMI over 30.

The definition of obesity varies depending on what one reads. In general, overweight and obesity indicate a weight greater than what is healthy. Obesity is a chronic condition defined by an excess amount of body fat. A certain amount of body fat is necessary for storing energy, heat insulation, shock absorption, and other functions.

Body mass index (BMI) is the best parameter for defining obesity, determined by a person's height and weight. BMI equals a person's weight in kilograms (kg) divided by their height in meters (m) squared (more information will be found later in the article).

Since BMI describes body weight relative to height, there is a strong correlation with total body fat content in adults:

How common is obesity?

Obesity has reached epidemic proportions in the United States. Over two-thirds of adults are overweight or obese, and one in three Americans is obese. The prevalence of obesity in children has increased markedly. Obesity has also been increasing rapidly throughout the world, and the incidence of obesity nearly doubled from 1991 to 1998. In 2015, nearly 40% of adults were obese in the U.S.

What is body mass index (BMI)?

The body mass index (BMI) is now the measurement of choice for many physicians and researchers studying obesity.

The BMI uses a mathematical formula that accounts for a person's weight and height.

The BMI measurement, however, poses some of the same problems as the weight-for-height tables. Not everyone agrees on the cutoff points for "healthy" versus "unhealthy" BMI ranges. BMI also does not provide information on a person's percentage of body fat. However, like the weight-for-height table, BMI is a useful general guideline and a good estimator of body fat for most adults ages 19-70. Besides, it may not accurately measure body fat for bodybuilders, certain athletes, and pregnant women.

The BMI equals a person's weight in kilograms divided by height in meters squared (BMI = kg/m2). To calculate the BMI using pounds, divide the weight in pounds by the height in inches squared and multiply the result by 703.

It is important to understand what "healthy weight" means. Healthy weight is defined as a body mass index (BMI) equal to or greater than 19 and less than 25 among all people 20 years of age or over. Generally, obesity is defined as a body mass index (BMI) equal to or greater than 30, which approximates 30 pounds of excess weight.

The World Health Organization uses a classification system using the BMI to define overweight and obesity.

The table below has already done the math and metric conversions. To use the table, find the appropriate height in the left-hand column. Move across the row to the given weight. The number at the top of the column is the BMI for that height and weight.

BMI (kg/m2) 19 20 21 22 23 24 25 26 27 28 29 30 35 40
Height (in.) Weight (lb.)
58 91 96 100 105 110 115 119 124 129 134 138 143 167 191
59 94 99 104 109 114 119 124 128 133 138 143 148 173 198
60 97 102 107 112 118 123 128 133 138 143 148 153 179 204
61 100 106 111 116 122 127 132 137 143 148 153 158 185 211
62 104 109 115 120 126 131 136 142 147 153 158 164 191 218
63 107 113 118 124 130 135 141 146 152 158 163 169 197 225
64 110 116 122 128 134 140 145 151 157 163 169 174 204 232
65 114 120 126 132 138 144 150 156 162 168 174 180 210 240
66 118 124 130 136 142 148 155 161 167 173 179 186 216 247
67 121 127 134 140 146 153 159 166 172 178 185 191 223 255
68 125 131 138 144 151 158 164 171 177 184 190 197 230 262
69 128 135 142 149 155 162 169 176 182 189 196 203 236 270
70 132 139 146 153 160 167 174 181 188 195 202 207 243 278
71 136 143 150 157 165 172 179 186 193 200 208 215 250 286
72 140 147 154 162 169 177 184 191 199 206 213 221 258 294
73 144 151 159 166 174 182 189 197 204 212 219 227 265 302
74 148 155 163 171 179 186 194 202 210 218 225 233 272 311
75 152 160 168 176 184 192 200 208 216 224 232 240 279 319
76 156 164 172 180 189 197 205 213 221 230 238 246 287 328

BMI to Appropriate Weight and Height Chart Courtesy of the National Institutes of Health

Below is a table identifying the risk of associated disease according to BMI and waist size.

Disease Risk* Relative to Normal Weight and Waist Circumference

BMI (kg/m2) Obesity Class Men 102cm (40 in) or less Women 88cm (35 in) or less Men > 102cm (40 in) Women > 88cm (35 in)
Underweight < 18.5
Normal weight 18.5 - 24.9
Overweight 25.0 - 29.9 Increased High
Obesity 30.0 - 34.9 I High Very High
Obesity 35.0 - 39.9 II Very High Very High
Extreme Obesity 40.0 + III Extremely High Extremely High

* Disease risk for type 2 diabetes, hypertension, and CVD.

+ Increased waist circumference can also be a marker for increased risk even in persons of normal weight.

Table Courtesy of the National Institutes of Health

QUESTION What is metabolism? See Answer

What are the most common causes of obesity?

The balance between calorie intake and energy expenditure determines a person's weight. If a person eats more calories than he or she burns (metabolizes), the person gains weight since the body will store the excess energy as fat. If a person eats fewer calories than he or she metabolizes, he or she will lose weight. Therefore, the most common causes of obesity are overeating and physical inactivity.

Ultimately, body weight is the result of genetics, metabolism, environment, behavior, and culture:

  1. Genetics: A person is more likely to develop obesity if one or both parents are obese. Genetics also affect hormones involved in fat regulation. For example, one genetic cause of obesity is leptin deficiency. Leptin is a hormone produced in fat cells and the placenta. Leptin controls weight by signaling the brain to eat less when body fat stores are too high. If, for some reason, the body cannot produce enough leptin or leptin cannot signal the brain to eat less, this control is lost, and obesity occurs. The role of leptin replacement as a treatment for obesity is under exploration.
  2. Physical inactivity: Sedentary people burn fewer calories than active people. The National Health and Nutrition Examination Survey (NHANES) shows strong correlations between physical inactivity and weight gain in both sexes.
  3. A diet high in simple carbohydrates: The role of carbohydrates in weight gain is not clear. Carbohydrates increase blood glucose levels, which in turn stimulate insulin release by the pancreas, and insulin promotes the growth of fat tissue and can cause weight gain. Some scientists believe that simple carbohydrates (sugars, fructose, desserts, soft drinks, beer, wine, etc.) contribute to weight gain because they are more rapidly absorbed into the bloodstream than complex carbohydrates (pasta, brown rice, grains, vegetables, raw fruits, etc.) and thus cause a more pronounced insulin release after meals than complex carbohydrates. This higher insulin release, some scientists believe, contributes to weight gain.
  4. Overeating: Overeating leads to weight gain, especially if the diet is high in fat. Foods high in fat or sugar (for example, fast food, fried food, and sweets) have high energy density (a lot of calories in a small amount of food). Epidemiologic studies have shown that diets high in fat contribute to weight gain.
  5. Frequency of eating: The relationship between frequency of eating (how often you eat) and weight is somewhat controversial. There are many reports of overweight people eating less often than people with normal weight. Scientists have observed that people who eat small meals four or five times daily have lower cholesterol levels and lower and/or more stable blood sugar levels than people who eat less frequently (two or three large meals daily). One possible explanation is that small frequent meals produce stable insulin levels, whereas large meals cause large spikes of insulin after meals.
  6. Medications: Medications associated with weight gain include certain antidepressants (medications used in treating depression), anticonvulsants (medications used in controlling seizures such as carbamazepine [Tegretol, Tegretol XR, Equetro, Carbatrol] and valproate [Depacon, Depakene]), some diabetes medications (medications used in lowering blood sugar such as insulin, sulfonylureas, and thiazolidinediones), certain hormones such as oral contraceptives, and most corticosteroids such as prednisone. Some high blood pressure medications and antihistamines cause weight gain. The reason for the weight gain with the medications differs for each medication. If this is a concern for you, you should discuss your medications with your physician rather than discontinuing the medication, as this could have serious effects.
  7. Psychological factors: For some people, emotions influence eating habits. Many people eat excessively in response to emotions such as boredom, sadness, stress, or anger. While most overweight people have no more psychological disturbances than normal-weight people, about 30% of the people who seek treatment for serious weight problems have difficulties with binge eating.
  8. Diseases: Diseases such as hypothyroidism, insulin resistance, polycystic ovary syndrome, and Cushing's syndrome are also contributors to obesity. Some diseases, such as Prader-Willi syndrome, can lead to obesity.
  9. Social issues : There is a link between social issues and obesity. Lack of money to purchase healthy foods or a lack of safe places to walk or exercise can increase the risk of obesity.

What are other factors associated with obesity?

Other factors associated with obesity include:

Health News

How is body fat measured?

BMI is a calculated value that approximates the body's fat percentage. Measuring a person's body fat percentage is not easy and is often inaccurate without careful monitoring of the methods. The following methods require special equipment, and trained personnel, can be costly, and some are only available in certain research facilities.

The following methods are simple:

Are weight-for-height tables useful to determine obesity?

Measuring a person's body fat percentage can be difficult, so other methods are often relied upon to diagnose obesity. Two widely used methods are weight-for-height tables and body mass index (BMI). While both measurements have their limitations, they are reasonable indicators that someone may have a weight problem. The calculations are easy, and no special equipment is required.

Most people are familiar with weight-for-height tables. Although such tables have existed for a long time, in 1943, the Metropolitan Life Insurance Company introduced their table based on policyholders' data to relate weight to disease and mortality. Doctors and nurses (and many others) have used these tables for decades to determine if someone is overweight. The tables usually have a range of acceptable weights for a person of a given height.

One problem with using weight-for-height tables is that doctors disagree over which is the best table to use. Several versions are available. Many have different weight ranges, and some tables account for a person's frame size, age, and sex, while other tables do not.

A significant limitation of all weight-for-height tables is that they do not distinguish between excess fat and muscle. A very muscular person may be classified as obese, according to the tables, when he or she is not.

Does it matter where body fat is located? (Is it worse to be an "apple" or a"pear"?)

The concern is directed not only at how much fat a person has but also where that fat is located in the body. The pattern of body fat distribution tends to differ in men and women.

In general, women collect fat in their hips and buttocks, giving their figures a "pear" shape. Men, on the other hand, usually collect fat around the belly, giving them more of an "apple" shape. (This is not a hard and fast rule; some men are pear-shaped and some women become apple-shaped, particularly after menopause.)

Apple-shaped people whose fat is concentrated mostly in the abdomen are more likely to develop many of the health problems associated with obesity. They are at increased health risk because of their fat distribution. While obesity of any kind is a health risk, it is better to be a pear than an apple.

To sort the types of body fat storage, doctors have developed a simple way to determine whether someone is an apple or a pear. The measurement is called the waist-to-hip ratio.

To find out a person's waist-to-hip ratio:

Women with waist-to-hip ratios of more than 0.8 and men with waist-to-hip ratios of more than 1.0 are "apples."

Another rough way of estimating the amount of a person's abdominal fat is by measuring the waist circumference. Men with a waist circumference of 40 inches or greater and women with a waist circumference of 35 inches or greater are considered to have increased health risks related to obesity.

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What can be done about obesity?

All too often, obesity prompts people to follow a strenuous diet in the hopes of reaching the "ideal body weight." Some amount of weight loss may be accomplished, but the weight usually quickly returns. Most people who lose weight regain their weight within five years. A more effective, long-lasting treatment for obesity must be found.

We need to learn more about the causes of obesity, and then we need to change the ways we treat it. When obesity is accepted as a chronic disease, it will be treated like other chronic diseases such as diabetes and high blood pressure. The treatment of obesity cannot be a short-term "fix" but has to be an ongoing lifelong process.

Obesity treatment must acknowledge that even modest weight loss can be beneficial. For example, a modest weight loss of 5%-10% of the initial weight, and long-term maintenance of that weight loss can bring significant health gains, including:

It is not necessary to achieve an "ideal weight" to derive health benefits from obesity treatment. Instead, the goal of treatment should be to reach and maintain a "healthier weight." The emphasis of treatment should be to commit to the process of lifelong healthy living, including eating more wisely and increasing physical activity.

What is the role of physical activity and exercise in obesity?

The National Health and Examination Survey (NHANES I) shows that people who engage in limited recreational activity are more likely to gain weight than more active people. Other studies have shown that people who engage in regular strenuous activity gain less weight than sedentary people.

Physical activity and exercise help burn calories. The amount of calories burned depends on the type, duration, and intensity of the activity. It also depends on the weight of the person. A 200-pound person will burn more calories running 1 mile than a 120-pound person because the work of carrying those extra 80 pounds must be factored in.

However, exercise as a treatment for obesity is most effective when combined with a diet and weight-loss program. Exercise alone without dietary changes will have a limited effect on weight because one has to exercise a lot to simply lose 1 pound. However regular exercise is an important part of a healthy lifestyle to maintain a healthy weight for the long term. Another advantage of regular exercise as part of a weight-loss program is a greater loss of body fat versus lean muscle compared to those who diet alone.

Other benefits of exercise

Remember, these health benefits can occur independently (with or without) achieving weight loss. Before starting an exercise program, talk to a doctor about the type and intensity of the exercise program.

General exercise recommendations

Exercise precautions

The following people should consult a doctor before vigorous exercise:

What is the role of diet in the treatment of obesity?

The first goal of dieting is to stop further weight gain. The next goal is to establish realistic weight-loss goals. While the ideal weight corresponds to a BMI of 20-25, this is difficult to achieve for many people. Thus, success is higher when a goal is set to lose 10%-15% of baseline weight as opposed to 20%-30% or greater. It is also important to remember that any weight reduction in an obese person would result in health benefits.

One effective way to lose weight is to eat fewer calories. One pound is equal to 3,500 calories. In other words, you have to burn 3,500 more calories than you consume to lose 1 pound. Most adults need between 1,200-2,800 calories per day, depending on body size and activity level to meet the body's energy needs.

Losing 1 pound per week is a safe and reasonable way to take off extra pounds. The higher the initial weight of a person, the more quickly he or she will achieve weight loss. This is because, for every 1 kilogram (2.2 pounds) of body weight, approximately 22 calories are required to maintain that weight. So for a woman weighing 100 kilograms (220 pounds), he or she would require about 2,200 calories a day to maintain his or her weight, while a person weighing 60 kilograms (132 pounds) would require only about 1,320 calories. If both ate a calorie-restricted diet of 1,200 calories per day, the heavier person would lose weight faster.

Age also is a factor in calorie expenditure. The metabolic rate tends to slow as we age, so the older a person is, the harder it is to lose weight.

There is controversy regarding carbohydrates (low-carb diet) and weight loss. When carbohydrates are restricted, people often experience rapid initial weight loss within the first 2 weeks. This weight loss is due mainly to fluid loss. When carbohydrates are added back to the diet, weight gain often occurs, simply due to a regain of the fluid.

Other diets such as low-fat diets all show a similar pattern of weight loss that is difficult to maintain if there are no additional general lifestyle changes.

General diet guidelines for achieving and (just as importantly) maintaining a healthy weight

What is the role of medication in the treatment of obesity?

Medication treatment of obesity should be used only in patients who have health risks related to obesity. Medications should be used in patients with a BMI greater than 30 or in those with a BMI of greater than 27 who have other medical conditions (such as high blood pressure, diabetes, and high blood cholesterol) that put them at risk for developing heart disease. Medications should not be used for cosmetic reasons.

Medications should only be used as an adjunct to diet modifications and an exercise program.

Like diet and exercise, the goal of medication treatment has to be realistic. With successful medication treatment, one can expect an initial weight loss of at least 5 pounds during the first month of treatment, and a total weight loss of 10%-15% of the initial body weight. It is also important to remember that these medications only work when they are taken. When they are discontinued, weight gain often occurs.

The first class (category) of medication used for weight control causes symptoms that mimic the sympathetic nervous system. They cause the body to feel "under stress" or "nervous." As a result, the major side effect of this class of medication is high blood pressure. This class of medication includes sibutramine (Meridia, which was taken off the market in the U.S. in October 2010 due to safety concerns) and phentermine (Adipex P). These medications also decrease appetite and create a sensation of fullness. Hunger and fullness (satiety) are regulated by brain chemicals called neurotransmitters. Examples of neurotransmitters include serotonin, norepinephrine, and dopamine. Anti-obesity medications that suppress appetite do so by increasing the level of these neurotransmitters at the junction (called synapses) between nerve endings in the brain.

Phentermine

Phentermine (Fastin, Adipex P) -- the other half of fen/phen -- suppresses appetite by causing a release of norepinephrine in the body. Phentermine alone is still available for the treatment of obesity but only on a short-term basis (a few weeks). The common side effects of phentermine include headache, insomnia, irritability, and nervousness. Fenfluramine (the fen of fen/phen) and dexfenfluramine (Redux) suppress appetite mainly by increasing the release of serotonin by the cells. Both fenfluramine and dexfenfluramine were withdrawn from the market in September 1997 because of the association of these two medications with pulmonary hypertension (a rare but serious disease of the arteries in the lungs) and the association of fen/phen with damage to the heart valves. Since the withdrawal of fenfluramine, some have suggested combining phentermine with fluoxetine (Prozac), a combination that has been referred to as phen/pro. However, no clinical trials have been conducted to confirm the safety and effectiveness of this combination. Therefore, this combination is not an accepted treatment for obesity.

Orlistat (Xenical, alli)

The next class (category) of drugs changes the metabolism of fat. Orlistat (Xenical, alli) is the only drug of this category that is U.S. FDA approved. This is a class of anti-obesity drugs called lipase inhibitors, or fat blockers. Fat from food can only be absorbed into the body after being broken up (a process called digestion) by digestive enzymes called lipases in the intestines. By inhibiting the action of lipase enzymes, orlistat prevents the intestinal absorption of fat by 30%. Drugs in this class do not affect brain chemistry. Theoretically, orlistat also should have minimal or no systemic side effects (side effects in other parts of the body) because the major locale of action is inside the gut lumen and very little of the drug is absorbed.

The U.S. Food and Drug Administration approved orlistat capsules, branded as alli, as an over-the-counter (OTC) treatment for overweight adults in February 2007. The drug had previously been approved in 1999 as a prescription weight loss aid, whose brand name is Xenical. The OTC preparation has a lower dosage than prescription Xenical.

Orlistat is recommended only for people 18 years of age and over in combination with a diet and exercise regimen. People who have difficulties with the absorption of food or who are not overweight should not take orlistat. Overweight is defined by the U.S. National Institutes of Health as having a body mass index (BMI) of 27 or greater.

Orlistat can be taken up to three times a day, with each fat-containing meal. The drug may be taken during the meal or up to one hour after the meal. If the meal is missed or is very low in fat content, the medications should not be taken.

The most common side effects of orlistat are changes in bowel habits. These include gas, the urgent need to have a bowel movement, oily bowel movements, oily discharge or spotting with bowel movements, an increased frequency of bowel movements, and the inability to control bowel movements. Women may also notice irregularities in the menstrual cycle while taking orlistat. Side effects are most common in the first few weeks after beginning to take orlistat. In some people, the side effects persist for as long as they are taking the drug.

People with diabetes, or thyroid conditions, who have received an organ transplant, or who are taking prescription medications that affect blood clotting should check with their physician before using OTC orlistat (alli) since drug interactions with certain medications are possible.

A long-term decrease in fat absorption can cause a deficiency of fat-soluble vitamins (such as vitamins A, D, E, K). Therefore, patients on orlistat should receive adequate vitamin supplementation.

Lorcaserin (Belviq)

In June 2012, the FDA approved Belviq (lorcaserin hydrochloride) as a weight-loss medication. The medication works by controlling appetite (via serotonin activation). According to the FDA data, nearly half the patients using the medication lost at least 5% of their starting weight, which is more than double that lost by patients in the control group. This was only true for patients without type 2 diabetes.

The medication is approved for patients who are obese (BMI >30) or overweight (BMQ >27) with one weight-related health issue. The predominant side effects were headache and dizziness, as well as fatigue. In patients with diabetes, low blood sugar was also a concern when taking Belviq.

Topiramate (Qsymia)

Qsymia is the newest medication approved for weight loss. It is a combination of phentermine and extended-release topiramate. As with the other medications, it is only approved for patients who are obese (BMI >30) or overweight (BMQ >27) with one weight-related health issue. According to the FDA data, a statistically significant greater proportion of the patients taking Qsymia achieved 5% and 10% weight loss. All patients in the study were also encouraged to eat a well-balanced, reduced-calorie diet.

It is important to note that Qsymia can lead to birth defects, and women need to know that they are not pregnant before starting the medication. Other possible serious side effects include increased heart rate, eye problems (glaucoma), and suicidal thoughts. In patients with diabetes, low blood sugar was also a concern when taking Qsymia.

Naltrexone (Contrave)

This is a combination drug of naltrexone (an opioid antagonist) and bupropion HCL (an antidepressant medication that is an inhibitor of the reuptake of dopamine and norepinephrine). The main side effects observed with this medication are nausea, constipation, and headaches. The medication is contraindicated in patients with uncontrolled hypertension or a history of seizures.

The medication is approved as an adjunct to dietary changes and increased physical activity in adults with an initial BMI of 30 or greater or 27 or greater with at least one comorbidity.

Liraglutide (Saxenda)

Saxenda was approved in late 2014 as a weight-loss drug in combination with physical activity and diet modifications. It is a once-a-day injection (not a pill) that mimics a hormone related to digestion and appetite control (GLP-1) that is used in the management of type 2 diabetes. It activates areas of the brain involved in appetite regulation.

Saxenda has been linked to thyroid tumors in rats and mice as well as pancreatitis in humans.

The medication is approved as an adjunct to dietary changes and increased physical activity in adults with an initial BMI of 30 or greater or 27 or greater with at least one comorbidity.

What is the role of weight loss surgery in the treatment of obesity?

The National Institute of Health consensus has suggested the following guidelines for weight loss surgery in obese patients:

A study done in Sweden compared the rates of diabetes and hypertension in two groups of obese patients: those who underwent surgery and those who didn't. Each group had a similar body weight at baseline (the start of the study). At two years, diabetes and high blood pressure were lower in the patients treated with surgery.

Surgical procedures of the upper gastrointestinal tract are collectively called bariatric surgery. The initial surgeries performed were the jejunocolic bypass and the jejunoileal bypass (where the small bowel is diverted to the large bowel, bypassing a lot of the surface area where food would have been absorbed). These procedures were fraught with problems and are no longer performed. Currently, procedures used include making the stomach area smaller or bypassing the stomach completely.

Currently, there are two types of bariatric surgery:

In cases of making the stomach smaller, vertically banded gastroplasty is the most common procedure, where the esophagus is banded early in the stomach. The other procedure is gastric banding, where an inflatable pouch causes gastric constriction. Changing the volume in the ring that encircles the stomach can change the amount of constriction. Gastric bypass essentially causes weight loss by bypassing the stomach.

The most common malabsorptive surgery is the Roux-en-Y gastric bypass, in which the stomach is stapled to create a small pouch, and then part of the intestine is attached to this pouch to decrease food absorption.

The surgical treatment of obesity and surgical procedures are evolving constantly and frequently are done by laparoscopic methods (using tiny incisions and a camera to carry out the surgery). Although these procedures are becoming more routine, the mortality rate for these procedures is still between 0.5%-2% with a significant incidence of complications.

The risks of surgery include the usual complications of infection, blood clots in the lower extremities (deep vein thrombosis) and in the lungs (pulmonary embolism), and anesthesia risk. Specific long-term risks related to obesity surgery include lack of iron absorption and iron deficiency anemia. Vitamin B12 deficiency can also develop and could lead to nerve damage (neuropathies). Rapid weight loss may also be associated with gallstones. Bariatric surgery should be performed at a center with a whole weight-loss program in place that includes dietitians and therapists and follow-up care.

Are meal substitutes, artificial sweeteners, and over-the-counter (OTC) products effective in treating obesity?

Meal substitutes

When used as substitutes for regular meals, meal substitutes are a convenient way to reduce calories as part of a low-calorie diet plan. A typical meal substitute available in powder and liquid form is Slim-Fast. Ensure is another meal substitute available in both liquid and bars. Meal substitutes should provide protein and be low in fat and calories. The label should include the number of calories per serving and the percentages of protein, carbohydrates, and fat. The total number of calories per serving is predetermined so it is easier to keep track of the daily consumption of calories. As with all dramatic changes in your diet, you should consult your healthcare provider to make sure that these changes will not have negative consequences.

Artificial sweeteners

Saccharin (Sweet'N Low) and aspartame (Equal) are sugar substitutes that provide little or no calories. They may be used as a substitute for table sugar. Using saccharin instead of a teaspoonful of sugar eliminates 33 calories from the diet. People with phenylketonuria (a serious genetic disease in which an individual is unable to break down and eliminate an amino acid, phenylalanine) should not use aspartame because it contains phenylalanine.

Fructose, sorbitol, and xylitol may be used as alternatives to sugar, but they provide more calories than saccharin and aspartame. Excessive use of sorbitol also may cause diarrhea.

OTC weight-loss products

Despite claims by manufacturers, the use of OTC products alone does not cause weight loss. Herbal weight-loss products or preparations called "fat burners" are even more misleading. These products may contain a combination of ma huang (a botanical source of ephedrine), white willow (a source of salicin), Hoodia gordonii, and/or guarana or kola nut (a source of caffeine). These agents are stimulants, which theoretically increase the metabolism and help the body break down fat. Nevertheless, there is no evidence that they are effective for weight loss. In addition, ma huang has been linked to serious side effects such as heart attacks, seizures, and death. Chromium also is a popular ingredient in weight-loss products, but there is no evidence that chromium has any effect on weight loss.

Weight-loss teas contain strong botanical laxatives (Senna, cascara sagrada) and diuretics (Rhamnus purshiana) that cause diarrhea and loss of water from the body. Diarrhea and water loss lead to the depletion of sodium and potassium and can lead to dehydration. Although an individual's weight may decrease, the loss is due to a decrease in fluid and is only temporary. Moreover, low sodium and potassium levels may cause abnormal heart rhythms and can even lead to death.

Guar gum preparations have also been promoted as a weight-loss agent. Guar gum is thought to work by leading to a feeling of fullness early in the meal. It has not been scientifically proven and has been associated with abdominal pain, gas, and diarrhea.

All of the OTC products discussed above are not considered drugs and are therefore not regulated by the Food and Drug Administration. As a result, there is little information on their effectiveness or safety. You should discuss any OTC weight loss products you are planning on taking or are taking with a healthcare professional.

It cannot be overemphasized that a successful program needs to be built on dietary and lifestyle changes.

Is there an herbal fen/phen preparation?

Since the withdrawal of fen/phen from the market, "herbal fen/phen" has been proposed as an alternative to treating obesity. However, the FDA has issued a warning that "herbal fen/phen" is not a safe and effective treatment for obesity and may contain ingredients that have been associated with injuries.

The main ingredients in most herbal fen/phen products are ephedrine and St. John's wort. Ephedrine acts like amphetamines in stimulating the central nervous system and the heart. Ephedrine promotes weight loss in part by an increase in the body's temperature, and when this happens, the body burns more calories. Ephedrine use has been associated with high blood pressure, heart rhythm irregularities, strokes, insomnia, seizures tremors, and nervousness. There have been reports of deaths in young individuals taking ephedrine.

How can people choose a safe and successful weight-loss program?

Almost any of the commercial weight-loss programs can work but only if they motivate you sufficiently to decrease the number of calories you eat or increase the number of calories you burn each day (or both). What elements of a weight-loss program should a consumer look for in judging its potential for safe and successful weight loss?

A responsible and safe weight-loss program should be able to document for you the five following features:

  1. The diet should be safe. It should include all of the recommended daily allowances (RDAs) for vitamins, minerals, and protein. The weight-loss diet should be low in calories (energy) only, not in essential foodstuffs.
  2. The weight-loss program should be directed toward a slow, steady weight loss unless your doctor feels your health condition would benefit from more rapid weight loss. Expect to lose only about a pound a week after the first week or two. With many calorie-restricted diets, there is an initial rapid weight loss during the first one to two weeks, but this loss is largely fluid.
  3. If you plan to lose more than 15 to 20 pounds, have any health problems, or take medication regularly, you should be evaluated by your doctor before beginning your weight-loss program. A doctor can assess your general health and any medical conditions that might be affected by dieting and weight loss. Also, a physician should be able to advise you on the need for weight loss, the appropriateness of the weight-loss program, and a sensible goal of weight loss for you. If you plan to use a very low-calorie diet (a special liquid formula diet that replaces all food intake for one to four months), you should do so under the close supervision of a healthcare professional.
  4. Your program should include plans for weight maintenance after the weight-loss phase is over. It is of little benefit to lose a large amount of weight only to regain it. Weight maintenance is the most difficult part of controlling weight and is not consistently implemented in weight-loss programs. The program you select should include help in permanently changing your dietary habits and level of physical activity, and altering a lifestyle that may have contributed to weight gain in the past. Your program should provide behavior modification help, including education in healthy eating habits and long-term plans to deal with weight problems. One of the most important factors in maintaining weight loss appears to be increasing daily physical activity. Try to be more active throughout the day and incorporate some simple calorie burners into your everyday routine. Even the most basic activities (such as taking an after-dinner walk, using the stairs at the mall or office instead of taking an escalator or elevator, park your car farther away so you have a longer walk) can get you prepared for more regular exercise like walking or jogging. You may choose to incorporate an individually tailored exercise program into your schedule.
  5. A commercial weight-loss program should provide a detailed statement of fees and costs of additional items such as dietary supplements.

What is the prognosis for obesity?

Obesity is a chronic condition. Too often it is viewed as a temporary problem that can be treated for a few months with a strenuous diet. However, as most overweight people know, weight control must be considered a lifelong effort. To be safe and effective, any weight-loss program must address the long-term approach, or else the program is largely a waste of time, money, and energy.

Scientists have made tremendous strides in understanding obesity and in improving the medication treatment of this important disease. In time, better, safer, and more effective obesity medications will be available. But currently, there is still no magic cure for obesity.

The best and safest way to lose fat and keep it off is through a commitment to a lifelong process of proper diet and regular exercise. Medications should be considered helpful adjuncts to diet and exercise for patients whose health risks from obesity outweigh the potential side effects of the medications. Medications should be prescribed by doctors familiar with the patient's conditions and with the use of the medications. Medication(s) and other "herbal" preparations with unproven effectiveness and safety should be avoided.

What are the health risks associated with obesity?

Obesity is not just a cosmetic consideration; it is harmful to one's health as it is a risk factor for many conditions. In the United States, roughly 112,000 deaths per year are directly related to obesity, and most of these deaths are in patients with a BMI over 30. Patients with a BMI over 40 have a reduced life expectancy.

Obesity also increases the risk of developing several chronic diseases, including the following:

How can you prevent obesity?

Maintaining your ideal body weight is a balancing act between food consumption and calories needed by the body for energy. You are what you eat. The kinds and amounts of food you eat affect your ability to maintain your ideal weight and to lose weight.

Medical science has established that eating proper foods can influence health for all age groups. The U.S. Department of Agriculture's current dietary guidelines state the following:

References

Droyvold, W.B., et al. "Weight change and mortality: the Nord-Trondelag Health Study." Journal of Internal Medicine 257.4: 338-345.

Life Measurements, Inc. (www.bodpod.com)

Manson, J.E., et al. "A prospective study of obesity and risk of coronary heart disease in women." N Engl J Med. 322.13 March 29, 1990: 882-9.

Sjöström, Lars, et al. "Lifestyle, Diabetes, and Cardiovascular Risk Factors 10 Years after Bariatric Surgery." New England Journal of Medicine 351 Dec. 23, 2004: 2683-2693.

Switzerland. World Health Organization. "Global Database on Body Mass Index."

United States. Centers for Disease Control and Prevention. National Center for Health Statistics. "National Health and Nutrition Examination Survey." July 17, 2019. <http://www.cdc.gov/nchs/nhanes.htm>.

United States. Food and Nutrition Service. U.S. Department of Agriculture. "Dietary Guidelines for Americans." <https://www.fns.usda.gov/cnpp/dietary-guidelines-americans>.

United States. National Institutes of Health. "Bioelectric Impedance Analysis in Body Composition Measurement." https://consensus.nih.gov/1994/1994bioelectricimpedancebodyta015pdf.pdf.