As Obesity Rate Soars, Hormone Offers New Hope
Americans are fatter than ever, with potentially disastrous consequences for their health, but injections of the recently discovered hormone leptin can help take some of the fat off, researchers said Tuesday at a UCLA seminar sponsored by the American Medical Assn.
The proportion of obese Americans--those at least 30% over ideal body weight--rose from 12% in 1991 to 17.9% in 1998, according to researchers from the Centers for Disease Control and Prevention.
In a separate study, Tufts University researchers found that 63% of men and 55% of women over the age of 25 are obese or overweight, the highest rate ever recorded.
Such obesity leads directly to at least 280,000 deaths every year and perhaps as many as 374,000, according to a new study from St. Luke’s-Roosevelt Hospital Center in New York City. That makes obesity the second-leading cause of preventable deaths after smoking, said Dr. Jeffrey P. Koplan, director of the CDC, and “a devastating public health threat.”
But there is hope. Other researchers from St. Luke’s have found in the first clinical trial of the widely touted hormone leptin that daily injections produced an average 15-pound loss over a six-month period.
The findings are all contained in today’s special issue of the Journal of the American Medical Assn. devoted to obesity.
The increase in obesity is somewhat paradoxical, said Dr. Phil B. Fontanarosa, interim co-editor of the journal. Interest in jogging, in-line skating, fitness in general and low-fat, low-calorie foods has never been higher, he said. Even so, 40% of adults engage in virtually no sustained exercise, and the consumption of fast foods is at an all-time high, he added. Weight loss is a $33-billion-a-year industry, with most patients looking for what he derisively called “a quick fix.”
The 11 articles in this week’s journal, he added, represent an attempt to get physicians to think more about the problem and to encourage them to offer more counseling to patients about the importance of diet and exercise.
The primary findings were from the CDC, where researchers led by Dr. Ali H. Mokdad phoned a randomly selected group of more than 100,000 people each year during the decade. Participants were asked questions about height, weight, smoking, alcohol use and a variety of other behaviors that increase their risk for one or more of the 10 leading causes of death in the United States.
“In a scant seven years [from 1991 to 1998], we had a 50% increase in obesity in all age groups and in all ethnic groups,” Koplan said. “We’ve had a steady increase [in obesity] throughout the 20th century, but this is a remarkably quick upturn. . . . We don’t have a simple answer why.”
Among the possible explanations he cited were an increase in average caloric consumption during the period, from 2,239 calories to 2,455 per day for men; growth in the fast food industry, which features meals containing higher calories and more fat; increased consumption of snack foods; and decreased levels of exercise, both at work and in free time.
Koplan cautioned that the CDC figures were “very conservative. People responding to surveys tend to underestimate their weight and overestimate their height.”
In fact, Aviva Must and her colleagues at the Tufts University School of Medicine found even grimmer numbers when they compiled results of physicians’ examinations conducted for the Third National Health and Nutrition Examination Survey. That study examined 16,884 adults over the age of 25 early in this decade.
Must’s group reports that 21% of men and 27% of women were obese and an additional 42% of men and 28% of women were overweight (less than 30% above ideal weight). The team also found that the incidence of high blood pressure, type 2 diabetes, gallbladder disease and osteoarthritis increased sharply with increasing obesity.
High cholesterol levels were also common among both the obese and the overweight, but did not seem to increase with increased weight.
All those symptoms lead to increased mortality. Focusing on six major health studies conducted during 1991, David B. Allison and his colleagues at St. Luke’s-Roosevelt concluded that obesity led to at least 280,000 deaths in that year and caused disease in many times that number.
The study, they wrote, “makes it clear that obesity is a major public health problem in the United States.”
One ray of hope was offered at the UCLA meeting by Dr. Steven B. Heymsfield of St. Luke’s-Roosevelt, who has been studying leptin. Discovered in 1994, leptin was the first hormone found to regulate body weight by regulating appetite. It is normally produced in fat cells and tells the brain to cut food consumption.
The gene for leptin was discovered in a strain of obese mice that have a defective version of it that causes them to eat incessantly. A very small number of humans have a similar defect, and results reported just last month indicate that leptin injections are “the first curative therapy” in such individuals, Heymsfield said.
His new study is the first to show that obese people who do not have a defective gene can be helped by leptin injections.
The St. Luke’s team studied 53 lean people and 70 obese individuals who received either leptin or a sham injection for a month. In the second phase, 47 of the obese people received either the drug or a placebo for another 20 weeks, while receiving counseling on exercise and a diet with 500 calories less than normal.
In the first four weeks, the team found that both groups receiving leptin lost weight, and for the obese, the loss was proportional to the dose. In the continuing study, those receiving the highest doses of leptin lost an average of 15 pounds over six months. Some lost more and, as is the case with most weight-loss drugs, some did not seem to respond at all.
Significantly, Heymsfield said, virtually all of the lost weight was from fat. Normally, in dieting, about 75% of lost weight is fat and 25% is muscle and bone, he added.
The only significant side effects from the program were problems at the injection sites, including black and blue marks, rashes and itching.
The researchers did not follow the participants after they ended the study, but it is fair to assume that many regained the weight, he said. To be effective, leptin would probably have to be taken on a lifetime basis, he added.
Heymsfield’s team used the natural form of the hormone, produced through genetic engineering techniques by Amgen Inc. of Thousand Oaks. The company has now developed a modified form of the drug that will allow physicians to administer higher doses; that hormone is being tested in nearly 1,000 people in the United States and Europe, said Dr. Mark McCamish of Amgen.
He speculated that it would be about five years before the drug would be widely available.
(BEGIN TEXT OF INFOBOX / INFOGRAPHIC)
Are You Overweight?
To find out if your weight is normal, find your height in the left-hand column and move across the row to your weight. The number at the top of the column is your body mass index (BMI). If it is 25 to 29, you are overweight. If it is 30 or above, you are obese.
Source: National Institutes of Health
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Obesity Increase
The incidence of self-described obesity (30 pounds or more overweight) grew between 1991 and 1998, with increases among both genders and all ages and races.
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Sources: Dr. Ali H. Mokdad, Journal of the American Medical Assn.
(BEGIN TEXT OF INFOBOX / INFOGRAPHIC)
Obesity Index
In a telephone survey, people were asked to give their weight and height. People were classified as obese if they were 30 pounds or more overweight. Below are the percentages of people by state who were obese.
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Source: Dr. Ali H. Mokdad et al, Journal of the American Medical Assn.
