Weight Management

Weight Management

by Kim Schoenhals

Americans are increasingly becoming overweight and obese, leading to numerous deaths and costing billions of dollars in health care. According to the surgeon general's office, 61 percent of adults, 13 percent of children aged 6 to 11 years, and 14 percent of adolescents aged 12 to 19 years were overweight or obese in 1999. In 2000, the cost of obesity-related health care in the United States reached $117 billion.

Obesity has become such a problem in the United States that the surgeon general launched a national action plan last year to combat the trend. "The prevalence of overweight and obesity has nearly doubled among children and adolescents since 1980," said former Surgeon General David Satcher at an international nutrition conference in January 2001. "It is also increasing in both genders and among all population groups of adults. We want to establish strategies and set priorities so that we can successfully implement obesity prevention efforts that focus on the family and community, schools, work sites, the health care delivery system and the media."

While weight may seem like a superficial problem to some, it is a serious health concern--300,000 Americans die each year from complications associated with obesity, such as heart disease, certain types of cancer, Type II diabetes, stroke, breathing problems and depression, according to the surgeon general's office.

In the simplest terms, a state of being overweight can be attributed to an imbalance between calorie consumption and calorie expenditure. However, there are numerous factors involved. For each individual, body weight is the result of a combination of genetic, metabolic, behavioral, environmental, cultural and socioeconomic influences, according to the surgeon general's office.

One method to determine the risk of developing obesity-related disease is to calculate body mass index (BMI), a number based on height and weight that gives a reasonable assessment of total body fat. The American Obesity Association (AOA) (www.obesity.org) noted a healthy BMI should fall between 18.5 and 24.9. A BMI of 25 to 29.9 is considered overweight, and anything above 30 is considered obese. A BMI above 40 indicates a severely obese individual who is at incredibly high risk for obesity-linked disease.

Another measurement that can be used to determine risk for various weight-related health problems is waist circumference. Those who have a high incidence of abdominal fat are at higher risk for disease. Men whose waists measure greater than 40 inches and women whose waists measure greater than 35 inches--in addition to having a BMI between 25 and 34.9--have a greater risk of developing Type II diabetes, hypertension and cardiovascular disease, according to AOA.

Most Americans are on a mission to combat their weight, whether they are a few pounds overweight or medically obese. According to the Natural Marketing Institute's (NMI) Health & Wellness Trends Database--three years of trended data from more than 2,000 consumer household respondents--59 percent of the general population is managing weight for health or appearance; however, only a fraction of those managing weight (29 percent) are using weight loss products. However, 34.4 percent of the general population has tried taking over-the-counter (OTC) medications, 33 percent has tried prescription medications and 25.9 percent has tried weight-loss supplements. Of those who have tried weight-loss supplements, 23.3 percent considered the method "extremely/very" successful, according to NMI.

Americans want to lose weight, with 63 percent of adults surveyed by Port Washington, N.Y.-based NPD Group in 2001 reporting the desire to lose 20 pounds. While it isn't easy to lose weight--and those on diets tend to lose lean muscle as well as fat--a healthy physique is possible to achieve and maintain by combining an exercise regimen with a healthy diet that is low in saturated fat and cholesterol, and high in fruits, vegetables and fiber. In addition to exercise and healthy eating, dietary supplements can aid weight management efforts by increasing metabolism, preserving lean muscle while eradicating fat, and blocking either starches or fat from digestion.

A majority of the general population is managing weight for health or appearance.

Yet less than 0ne-third of "weight managers" are using weight-loss products.

Herbs and Botanicals

One of the most well-known supplements for weight-loss efforts is ephedra (a.k.a. ma huang). Ephedra is a thermogenic and a stimulant, meaning it promotes calorie burning and increases heart rate, although these effects have also linked it to serious adverse cardiovascular and central nervous system events. Researchers from the New England Medical Center in Boston reviewed adverse event reports (AERs) submitted to the Food and Drug Administration (FDA) that involved ephedra use, and concluded that the herb is temporally related to stroke, myocardial infarction and sudden death.¹

However, a collaboration of researchers from the New York Obesity Research Center at St. Luke's-Roosevelt Hospital, as well as other centers, conducted a study to determine the safety and efficacy of ephedra in combination with gotu kola (a natural source of caffeine) for weight loss--they determined the combo was safe and effective.² Industry associations, such as the Council for Responsible Nutrition (CRN), recommend that ephedra be taken in doses of 25 mg or less no more than three times daily, for no more than 90 mg/d, and no longer than six months chronically.

According to John Hathcock, Ph.D., vice president of nutritional and regulatory science at CRN, responsible ephedra manufacturers label their products with warnings regarding heart disease, high blood pressure and additional chronic disease that requires medication, and most studies exclude subjects who fall into those categories. "There are exclusion criteria and selection criteria for the study population," Hathcock said regarding the New York Obesity Research Center study that deemed the ephedra-caffeine combination safe and effective. "The exclusion and restriction criteria are suggested in the labeling, which consumers should read and pay attention to, and are exactly commensurate with the clinical trial exclusion criteria. If you've got heart disease, high blood pressure, are taking medication, etc., you should not be using ephedra, and the label says so."

Another herb purportedly effective for weight loss is yohimbe, which is derived from the bark of an African tree. Like ephedra, the active alkaloid of yohimbe--yohimbine--affects the central nervous and cardiovascular systems. Because of this, yohimbine has been thought to increase the risk for hypertension and has been contraindicated from use with tricyclic antidepressants.³

Researchers studying the effects of various weight-loss regimens determined that the addition of yohimbine improved cardiac work during exercise. The researchers prescribed low-calorie diets to three groups of nine obese women for 10 days. One group received the diet only, another received ephedrine (25 mg twice daily) with caffeine (200 mg twice daily); and the third group received ephedrine (25 mg twice daily), caffeine (200 mg twice daily) and yohimbine (5 mg twice daily). When the study period ended, the women in the yohimbine group exhibited increased diastolic blood pressure and heart rate compared to the other groups. Researchers concluded that while ephedra and caffeine minutely affected the cardiovascular system, the addition of yohimbine attenuated cardiac performance during rest and increased cardiac work during exercise.⁴

Guarana is another stimulant commonly used in weight-loss applications. An herbal preparation containing guarana, as well as yerba mate and damiana, delayed gastric emptying, reduced the time to perceived fullness and induced weight loss. Researchers from the Medical Center Charlottenlund in Denmark administered an herbal preparation containing yerba mate (Ilex paraguayensis), guarana (Paullinia cupana) and damiana (Turnera diffusa var. aphrodisiaca) to 47 healthy overweight patients in a double blind, placebo-controlled fashion. After 45 days of treatment, the patients in the treatment group demonstrated significant weight loss.⁵

When used in combination with ephedra, guarana can effectively promote short-term weight and fat loss, according to researchers from St. Luke's-Roosevelt Hospital Center and Department of Medicine. They randomly administered treatment--72 mg/d of ephedrine alkaloids and 240 mg/d of caffeine from guarana--or placebo to 67 patients for eight weeks. Active treatment produced significantly greater loss of weight and fat than placebo.⁶ However, because of the combined stimulant effects of guarana and ephedra, researchers from the Louisiana State University School of Medicine in New Orleans stated that while the combination may have some benefit, it may also have serious side effects.⁷

The same reviewers stated that a combination of hydroxycitric acid (HCA) from Garcinia cambogia does not perform any more effectively in clinical trials than placebo. Researchers from St. Luke's-Roosevelt Hospital in New York came to the same conclusion. They studied 135 subjects who were administered a high-fiber, low-energy diet, and one group received placebo while the other received 1,500 mg/d of HCA. After 12 weeks of treatment, both groups exhibited significant weight loss, although there was no difference between the groups in the amount of weight lost.⁸ Similarly, researchers from Purdue University in Lafayette, Ind., conducted a double blind, placebo-controlled trial involving 89 mildly overweight females and determined that HCA did not exhibit any appetite-suppressive properties, nor did it enhance weight loss.⁹

HCA is suspected to inhibit an enzymatic process that allows glucose to be converted to fat, and by inhibiting the enzyme, HCA is purported to decrease fat synthesis and promote fat burning. It does appear to have a clinically significant effect on weight and fat loss, according to one double blind, placebo-controlled study. Participants consuming 1,320 mg/d of HCA (as CitriMax, manufactured by InterHealth Nutraceuticals Inc. in Benicia, Calif.) exhibited significantly greater weight loss as a result of fat loss than the placebo group. In addition, subjects in the treatment group reported a decrease in appetite that was not reported in the placebo group.¹⁰

Researchers from Georgetown University Medical Center recently completed another trial comparing the effects of HCA on body weight and BMI. Eighty-two participants were divided into three groups: 1) 2,800 mg/d of HCA (as Super CitriMax, manufactured by InterHealth); 2) 2,800 mg/d of HCA, 400 mcg/d of niacin-bound chromium (as ChromeMate, manufactured by InterHealth) and 400 mg/d of Gymnema sylvestre extract; or 3) placebo. After eight weeks, both treatment groups exhibited a decrease in body weight and BMI, although greater results were seen with the combination of HCA, chromium and Gymnema sylvestre. The HCA-only group exhibited a 5-percent decrease in body weight and a 7-percent reduction in BMI, while the combination group exhibited a 6.5-percent decrease in body weight and a 9.2-percent reduction of BMI. In contrast, the placebo group experienced reductions of 1.9 percent in body weight and 2 percent in BMI. Researchers also noted appetite was significantly reduced in both treatment groups.¹¹

Animal studies involving HCA have indicated that the extract suppressed fatty acid synthesis, lipogenesis and food intake, as well as induced weight loss.¹² One animal study in particular, conducted by researchers at the Swiss Federal Institute of Technology in Schwerzenbach, Switzerland, determined that HCA increased energy expenditure and reduced weight gain after substantial weight loss.¹³

Another herb suggested for weight management is Coleus forskohlii, an Ayurvedic preparation thought to affect blood glucose levels by stimulating the release of insulin and glucagon.¹⁴ In one open-field study involving six overweight women, forskolin--a root extract of Coleus forskohlii--was shown to reduce body mass. The women were overweight but otherwise healthy at baseline and were instructed to take 250 mg of forskolin (as ForsLean, manufactured by Piscataway, N.J.-based Sabinsa Corp.) twice daily 30 minutes before meals for eight weeks. At the end of the study period, mean values for body weight and fat content significantly decreased, and lean body mass increased. In addition, the regimen was not found to adversely affect blood pressure or pulse rate.¹⁵

Gymnema sylvestre is an Ayurvedic herb suggested to interfere with the ability to taste sweetness, which lends it to diabetes and weight management applications. Gymnema leaves have been shown to raise insulin levels in healthy subjects¹⁶, and it has been noted to reduce intestinal glucose uptake.¹⁷

Bitter orange (Citrus aurantium) is also thought to offer a benefit in weight management and is said to have thermogenic effects. The active agents in C. aurantium are its alkaloids, including synephrine, hordenine, octopamine, tyramine and N-methyltyramine, according to Dennis Jones, Ph.D., who is the inventor of Advantra Z, an extract of zhi shi (immature bitter orange). (Editor's note: The Advantra Z trademark belongs to Burlington, Vt.-based Zhishin LLC, although Wayne, N.J.-based Nutratech has license to sell it.)

Scientifically, zhi shi extract has been demonstrated to increase metabolism after a high protein meal. Researchers from the Royal Victoria Hospital in Montreal studied C. aurantium for its thermogenic effects on obese subjects. Five women participated in the three-day study and followed strict measures to control energy expenditure and heart rate. Researchers noted the thermogenic response to meals was significantly greater with intake of C. aurantium (as Advantra Z), and the women's heart rates and blood pressure remained constant throughout the study. Researchers concluded that C. aurantium supplementation may increase the thermogenic response of a high protein meal by 4 percent (approximately 60 kcalories/d) and enhance weight control.¹⁸

In another study, zhi shi extract was combined with caffeine and St. John's wort to determine its effects on body fat loss, lipid levels and mood states in overweight healthy adults. The treatment group received 975 mg/d of C. aurantium (as Advantra Z), 528 mg/d of caffeine and 900 mg/d of St. John's wort. At the end of the study period, the treatment group exhibited a significant loss of body weight and fat compared with placebo and control groups. Researchers from Greenwich Hospital in Connecticut concluded that the combination of C. aurantium, caffeine and St. John's wort, in addition to mild caloric restriction and exercise, safely and effectively promoted body weight and fat loss.¹⁹

Exercise And Food Intake Are Top Weight Loss Methods Used By Consumers
Source: The Health & Wellness Trends Database
The Natural Marketing Institute, 2002

Consumer-Reported Success Of Various Weight Loss Methods
Source: The Health & Wellness Trends Database
The Natural Marketing Institute, 2002

Fatty Acids and Minerals

Aside from herbal and botanical products, fatty acids and minerals are also thought to play a role in weight management. Gamma linolenic acid (GLA), for example, is an omega-6 fatty acid that has thermogenic properties, can increase metabolism and stimulate fat loss. "GLA, one of the most potent omega-6 fatty acids found in evening primrose oil, borage oil and black currant oil, has been found to ... boost the metabolic rates in healthy adults," wrote Ann Louise Gittleman, author of Eat Fat, Lose Weight (Keats Publishing, 1999). "GLA is the raw material needed for certain prostaglandins to ignite the mitochondria's fat-burning process in the body's brown fat."

Insulin resistance occurs when the body's system of counteracting raised glucose (blood sugar) levels malfunctions. When insulin resistance sets in, the pancreas releases large amounts of insulin to the muscles for converting glucose to glycogen, a suspected precursor to obesity, high blood pressure and Type II diabetes. In order to combat weight gain associated with insulin resistance, the body's metabolism must be repaired.

Conjugated linoleic acid (CLA), a naturally occurring isomer of linoleic acid, or omega-6, is considered by some to be an insulin aid. While research on this mechanism of action is conflicting, CLA has been shown to be effective for reducing body fat. In one study conducted by researchers at the University of Uppsala in Sweden, patients who were taking CLA exhibited a 3.8-percent reduction of body fat. Patients (n=53) were randomly assigned to receive either 4.2 g/d of CLA (as Tonalin CLA, distributed by Vernon Hills, Ill.-based Natural Inc.) or placebo for 12 weeks, at the end of which, the proportion of body fat in the supplement group was reduced.²⁰ And, in another study conducted by researchers at Uppsala University, CLA supplementation of 4.2 g/d induced a decrease in abdominal fat in obese men after four weeks.²¹ Another study published by researchers at Scandinavian Clinical Research in Kjeller, Norway, indicated that in combination with a regimen of 90 minutes of strenuous exercise three times per week, CLA (as Tonalin CLA) reduced body fat in subjects with normal body weight without affecting weight at a dose of 1.8 g/d.²²

In addition to assisting as an insulin aid, CLA may also be able to increase energy expenditure, according to an animal study conducted by researchers at Utrecht University in The Netherlands. However, scientists also noted the mice who were supplemented with CLA exhibited an enlargement of their livers, which may warrant further safety studies.²³

An herbal extract of Laberstroemia speciosa L. is also believed to act as an insulin aid by modifying the activity of glucose transport, thereby lowering blood glucose levels. According to researchers from the Central Research Institute in Shizuoka, Japan, Lagerstroemia speciosa L. (as Glucosol, manufactured by Los Angeles-based OptiPure) has hypoglycemic effects and can suppress the elevation of blood plasma glucose levels in mice with non-insulin dependent diabetes mellitus.²⁴ In another animal study, researchers from the same institute tested the anti-obesity activity of Lagerstroemia speciosa L. on five-week-old mice. The mice in the treatment group exhibited a significant reduction in body weight gain and parametrial adipose tissue weight as compared to the control group.²⁵

Chromium, an essential trace mineral, is also believed to affect insulin resistance and assist in weight loss. Chromium improves the efficacy of insulin by assisting in the metabolism of carbohydrates, lipids and proteins. Chromium is also necessary for the cellular uptake of glucose, and supplementation with the mineral is believed to combat insulin resistance, as well as promote fat loss while preserving lean body mass. In a review of functional food products, authors from Functional Foods Inc. based in Belmont, Mass., stated that chromium promotes fat loss over muscle loss.²⁶

Researchers from Decades Inc. in Washington, D.C., conducted a pilot study to determine whether 600 mcg/d of niacin-bound chromium for two months in combination with a modest dietary and exercise regimen could influence weight loss and body composition. They learned that in the 20 overweight women who participated in the randomized, double blind trial, those receiving the supplement (as ChromeMate manufactured by InterHealth) lost a significantly greater amount of fat and preserved a greater level of lean body mass than the placebo group.²⁷

A study conducted by researchers at the Health and Medical Research Foundation in San Antonio utilizing chromium picolinate noted similar results. The randomized, double blind, placebo-controlled study involved 122 subjects who took 400 mcg/d of chromium picolinate (as Chromax by Nutrition 21 in Purchase, N.Y., which holds a use patent for chromium picolinate for body composition). In addition, all subjects' caloric intake and exercise were controlled. After three months, subjects in the supplement group demonstrated a more significant loss of weight and fat mass as compared to placebo, leading researchers to conclude that daily supplementation with chromium picolinate can lead to significant improvements in body composition, particularly when the changes are corrected for differences in caloric intake and exercise.²⁸

Contrarily, a study conducted by researchers at the University of Massachusetts, Amherst, indicated that chromium picolinate (as Chromax) at 400 mcg/d for 12 weeks with a concomitant weight lifting and walking regimen did not significantly affect body composition.²⁹

"When you look at the data, people lost more body fat when taking [chromium picolinate] than the control group," said James Komorowski, Ph.D., director of technical services at Nutrition 21. "However, the number was not significant enough to show an effect. The people on placebo didn't lose much body fat, but the [treatment] group lost a significant amount of fat. It was just the number of subjects was so low, they didn't get a statistical significance."

Calcium is another mineral that may have an impact on weight management by determining body fat percentages. Researchers from the University of Utah discovered that higher intakes of calcium early in life led to lower childhood body fat percentages. For eight years, researchers followed 53 healthy children (ages two to eight) whose dietary fat intake was 30 to 33 percent of total calories. Through dietary questionnaires, researchers noted that higher mean calcium intake was associated with lower body fat.³⁰

Manganese may also have application in weight management because of its suspected effect on insulin function, although the majority of research in this area has been conducted with animals. Manganese deficiency is thought to impair pancreatic insulin secretion, which can lead to errors in glucose metabolism and gains in body fat, according to Max Motyka, M.S.R., Ph.D., director of the human products division at Clearfield, Utah-based Albion Advanced Nutrition. Additional signs of manganese deficiency include defects in lipid and carbohydrate metabolism and severe pancreatic abnormalities.

"Manganese supplementation completely reverses the abnormalities in pancreas and glucose tolerance ..." wrote Eckhard Ziegler and L.J. Filer Jr., editors of Present Knowledge in Nutrition (ILSI Press, 1996). "In addition to its effect on pancreatic tissue integrity, manganese deficiency can directly impair pancreatic insulin synthesis and secretion."

Vanadium is another mineral that has an effect on insulin and may play a role in weight management, according to Motyka. Researchers from the University of Hamburg in Germany stated that a representative set of vanadium (IV and V) has the ability to stimulate glucose uptake by cells.³¹ Researchers from the University of British Columbia in Vancouver, Canada, conducted a study on diabetic rats and determined that insulin and vanadium treatment positively affected glycogen synthase, glycogen synthase kinase-3 and protein phosphatase-1 activity. However, the researchers noted vanadium did not stimulate glycogen synthesis in skeletal muscle, which they suggested meant an involvement of other metabolic pathways in the observed glucoregulatory effect of vanadium.³²

Miscellaneous Extracts

While maintaining normal insulin levels is important for weight management, so is restricting carbohydrate intake because carbohydrate metabolism affects insulin levels and can lead to weight gain and obesity. There are a few dietary supplement ingredients available that inhibit alpha amylase activity--the enzymatic process that breaks down starchy foods--and so are known as "starch blockers." Commercial starch blockers often contain protein extracted from white kidney beans or wheat.

An extract of Phaseolus vulgaris (white kidney bean) has been shown in preliminary research conducted by scientists at the University of Scranton, N.C., to reduce starch absorption. Subjects taking 1.5 g of the bean extract (as Phase 2, manufactured by Pharmachem Laboratories in Kearny, N.J.) with four slices of white bread absorbed 66 percent less starch than the participants taking the bread alone.³³ An additional clinical trial conducted by researchers in Italy demonstrated similar results, with subjects in the supplement group (500 mg/d of Phase 2 in Blockal) absorbing 57 percent less starch than the placebo group. In addition, the supplement group lost an average of 6.5 pounds without losing lean muscle as compared to 1 pound in the placebo group, and the supplement group lost 10.5 percent of body fat mass, 1.4 percent of hip circumference, 1.4 percent of thigh circumference and 3.4 percent of waist circumference.³⁴

In studying wheat-derived starch blockers, researchers from the Gastroenterology Research Unit at the Mayo Clinic learned that it blocked salivary amylase. They hypothesized that this effect may delay the digestion of starch long enough to prolong the feeling of fullness and reduce food consumption. However, researchers determined this dose (1.5 g with meals for nine weeks) may be effective for diabetes mellitus but not obesity.³⁵ In subsequent research, scientists stated that amylase inhibition induces carbohydrate tolerance, satiety and weight loss, making wheat-derived starch blockers potentially useful for treating obesity. They determined that wheat-derived amylase inhibitors effectively restrain human pancreatic amylase activity.³⁶

In addition to starch blockers, fat blockers are also available to facilitate weight loss. One such fat blocker, chitosan, is a polymer of glucosamine derived from chitin, a fiber taken most often from the exoskeletons of shellfish. Chitosan is purported to draw fat molecules to it, causing them to be excreted before the body can absorb them. Because of this action, chitosan has been recommended in weight-loss applications.

Rapidly soluble chitosan was shown to be effective in facilitating weight loss and reducing body fat in one study conducted by researchers from the American Institute for Biosocial and Medical Research Inc. in Tacoma, Wash. They studied 59 overweight, otherwise healthy women who had a history of daily dietary fat consumption greater than or equal to 30 percent of total calories. During the randomized, double blind, placebo-controlled trial, subjects received either three capsules of rapidly soluble chitosan (a total of 1.5 g) or placebo twice daily for eight weeks. No food restrictions or modifications were assigned, and subjects were instructed to continue their regular caloric intake. Subjects in the treatment group (taking Liposan Ultra, manufactured by Redmond, Wash.-based Vanson Inc.) experienced decreased mean body weight and BMI compared to baseline, while subjects in the placebo group increased mean weight, BMI and percent body fat, as well as decreased lean body mass.³⁷

Conversely, researchers from the University of California, Davis, administered a high-fat diet to seven healthy male volunteers with an average BMI of 26 for 12 days. On days six to nine, subjects consumed chitosan (as Liposan Ultra in Fat Trapper Plus, manufactured by Pacoima, Calif.-based Enforma Natural Products) prior to meals and snacks for a total of 5.25 g/d. Fat excretion did not differ between the two periods, and researchers concluded that chitosan did not block fat absorption.³⁸ And, researchers from Singapore General Hospital determined that in the absence of dietary modifications, chitosan (as Absorbitol, manufactured by Lake Bluff, Ill.-based Pharmanutrients) did not bring about improvements in weight or body composition.³⁹

However, according to an unpublished double blind, crossover study conducted by Susie Rockway, Ph.D., director of scientific and clinical affairs for Pharmanutrients, chitosan was shown to reduce fat in six subjects who took 1,000 mg of chitosan (as Absorbitol) prior to eating twice daily for 12 days. "What we were doing was proving that what we have seen in the laboratory, we can now show in the human body as well," Rockway said. "Our conclusion was that chitosan does decrease fat absorption."

Another kind of "blocker," 5-HTP (5-Hydroxytryptophan) is an appetite suppressant recommended for weight-loss applications by reducing carbohydrate and fat intake. A molecule produced in the body from tryptophan, 5-HTP is an amino acid used to create serotonin. Brain levels of these chemicals influence appetite, according to Ray Sahelian, M.D., author of 5-HTP: Nature's Serotonin Solution (Avery Publishing Group Inc., 1998). "One of the most important neurotransmitters involved in satiety is serotonin," he wrote. "Pharmacological, biochemical and behavioral evidence accumulated over the past three decades suggests that serotonin tends to inhibit eating behavior. Short-term observations have shown that 5-HTP, even without dietary restrictions, causes loss of interest in food, decreased food intake and weight loss in obese individuals."

As Americans continue to consume high-starch, high-fat diets, the rate of obesity in the United States is sure to continue its rise. While a healthy diet and an exercise regimen are the surest way to manage weight, dietary supplements can aid this goal by enhancing fat loss and lean mass maintenance, blocking starches and fats, and controlling appetite. As more promising clinical trials are published, these ingredients will become more popular and America can begin a new trend of slimming down.

Editor's Note: For a full list of references to this story, please visitReferences.